In order to meet with the demands of pregnancy, physiological adaptations occur in the mother. These adaptations allow her to support and protect the foetus. In this article, we will take a systems based approach to discuss the different changes which occur during pregnancy. During pregnancy a woman experiences a change in her endocrine system. Therefore, the free T3 and T4 levels remain unchanged — but the total T3 and T4 levels rise.
The renin-aldosterone system during normal and hypertensive pregnancy. Roles of the circulating renin-angiotensinaldosterone system in tthe pregnancy. Thyroid There is an increase in the production of thyroxine-binding globulin Tye by the liver, resulting in increased levels of thyroxine T 4 and tri-iodothyronine T 3. This contributes to insulin resistance of pregnancy and possibly striae. Maternal insulin resistance begins in the second trimester and peaks in the third trimester. The fallopian tubes, ovaries, and ligaments supporting the uterus all enlarge and elongate. Bleaching the anus Matern Fetal Neonatal Med. Progesterone causes the uterus chxnges increase in size to accommodate the growing fetus. Oedema of the hands may also occur. This sort of evidence supports the notion that natural selection Reproductive changes of the pregnant woman played a dimorphic role in designing the anatomy of the vertebral lumbar region.
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The resulting increase in intragastric pressure combined with lower LES tone leads to the gastroesophageal reflux commonly experienced during pregnancy. During the Reproducttive the fusion of gametesthe zygote is formed. Letter from the Editor: Welcome to Parenthood. Later in pregnancy, the woman might develop physiological hydronephrosis and hydroureter, which are normal. The first meiotic division is completed just before ovulation. Ovary and ovulation 3. By cuanges used of this site, you agree to our Reproductive changes of the pregnant woman of cookies. The developing fetus needs a constant supply of oxygen and nutrients carried through Reproductive changes of the pregnant woman blood, so injury may result from a lack of fluid. To positionally compensate the additional load due to the pregnancy, pregnant mothers often extend their lower backs. The pituitary gland grows by about one-third as a result of hyperplasia of the lactrotrophs in response to the high plasma estrogen. In fact, the biggest factors affecting ptosis are cigarette smoking, a chagnes body mass index BMIher number of pregnanciesher breast cup size before pregnancy, and age.
Physiological changes occur in pregnancy to nurture the developing foetus and prepare the mother for labour and delivery.
- Around menopause , changes in the genital organs occur rapidly.
- Pregnancy brings a variety of changes to the body.
- As a woman ages, a number of changes take place in the female reproductive system.
Physiological changes occur in pregnancy to nurture the developing foetus and prepare the mother for labour and delivery. Some of these changes influence normal biochemical values while others may mimic symptoms of medical disease. It is important to differentiate between normal physiological changes and disease pathology. This review highlights the important changes that take place during normal pregnancy.
During pregnancy, the pregnant mother undergoes significant anatomical and physiological changes in order to nurture and accommodate the developing foetus. These changes begin after conception and affect every organ system in the body.
It is important to understand the normal physiological changes occurring in pregnancy as this will help differentiate from adaptations that are abnormal. Plasma volume increases progressively throughout normal pregnancy.
Because the expansion in plasma volume is greater than the increase in red blood cell mass, there is a fall in haemoglobin concentration, haematocrit and red blood cell count. Despite this haemodilution, there is usually no change in mean corpuscular volume MCV or mean corpuscular haemoglobin concentration MCHC. The platelet count tends to fall progressively during normal pregnancy, although it usually remains within normal limits. Pregnancy causes a two- to three-fold increase in the requirement for iron, not only for haemoglobin synthesis but also for for the foetus and the production of certain enzymes.
There is a to fold increase in folate requirements and a two-fold increase in the requirement for vitamin B Concentrations of endogenous anticoagulants such as antithrombin and protein S decrease. Thus pregnancy alters the balance within the coagulation system in favour of clotting, predisposing the pregnant and postpartum woman to venous thrombosis.
This increased risk is present from the first trimester and for at least 12 weeks following delivery. In vitro tests of coagulation [activated partial thromboplastin time APTT , prothrombin time PT and thrombin time TT ] remain normal in the absence of anticoagulants or a coagulopathy. This is due to compression of the left iliac vein by the left iliac artery and the ovarian artery.
On the right, the iliac artery does not cross the vein. The primary event is probably peripheral vasodilatation. This is achieved predominantly via an increase in stroke volume, but also to a lesser extent, an increase in heart rate.
There is a minimal fall at term. An increase in stroke volume is possible due to the early increase in ventricular wall muscle mass and end-diastolic volume but not end-diastolic pressure seen in pregnancy. The heart is physiologically dilated and myocardial contractility is increased. Although stroke volume declines towards term, the increase in maternal heart rate 10—20 bpm is maintained, thus preserving the increased cardiac output. Blood pressure decreases in the first and second trimesters but increases to non-pregnant levels in the third trimester.
There is a profound effect of maternal position towards term upon the haemodynamic profile of both the mother and foetus. In the supine position, pressure of the gravid uterus on the inferior vena cava IVC causes a reduction in venous return to the heart and a consequent fall in stroke volume and cardiac output.
Pregnant women should therefore be nursed in the left or right lateral position wherever possible. If the woman has to be kept on her back, the pelvis should be rotated so that the uterus drops to the side and off the IVC, and cardiac output and uteroplacental blood flow are optimised. Reduced cardiac output is associated with a reduction in uterine blood flow and therefore in placental perfusion, which could compromise the foetus.
Although both blood volume and stroke volume increase in pregnancy, pulmonary capillary wedge pressure and central venous pressure do not increase significantly.
Pulmonary vascular resistance PVR , like systemic vascular resistance SVR , decreases significantly in normal pregnancy. Pulmonary oedema will be precipitated if there is either an increase in cardiac pre-load such as infusion of fluids or increased pulmonary capillary permeability such as in pre-eclampsia or both.
Following delivery there is an immediate rise in cardiac output due to relief of the inferior vena cava obstruction and contraction of the uterus, which empties blood into the systemic circulation.
Transfer of fluid from the extravascular space increases venous return and stroke volume further. Cardiac output has nearly returned to normal pre-pregnancy values two weeks after delivery, although some pathological changes e.
The above physiological changes lead to changes on cardiovascular examination that may be misinterpreted as pathological by those unfamiliar with pregnancy. The murmur may be loud and audible all over the precordium, with the first heart sound loud and possibly sometimes a third heart sound. There may be ectopic beats and peripheral oedema. Normal findings on ECG in pregnancy that may partly relate to changes in the position of the heart include:.
The primary adaptive mechanism in pregnancy is a marked fall in systemic vascular resistance SVR occurring by week six of gestation. The fall in SVR is combined with increased renal blood flow and this is in contrast to other states of arterial under-filling, such as cirrhosis, sepsis or arterio-venous fistulas.
Relaxin, a peptide hormone produced by the corpus luteum, decidua and placenta, plays an important role in the regulation of haemodynamic and water metabolism during pregnancy. Serum concentrations of relaxin, already elevated in the luteal phase of the menstrual cycle, rise after conception to a peak at the end of the first trimester and fall to an intermediate value throughout the second and third trimester. Relaxin stimulates the formation of endothelin, which in turn mediates vasodilation of renal arteries via nitric oxide NO synthesis.
Despite activation of the renin—angiotensin—aldosterone RAA system in early pregnancy, a simultaneous relative resistance to angiotensin II develops, counterbalancing the vasoconstrictive effect and allowing profound vasodilatation. In addition, the increase in plasma volume causes decreased oncotic pressure in the glomeruli, with a subsequent rise in GFR. As the GFR rises, both serum creatinine and urea concentrations decrease to mean values of about The increased renal blood flow leads to an increase in renal size of 1—1.
The kidney, pelvis and calyceal systems dilate due to mechanical compressive forces on the ureters. Progesterone, which reduces ureteral tone, peristalsis and contraction pressure, mediates these anatomical changes. Urinary stasis in the dilated collecting system predisposes pregnant women with asymptomatic bacteriuria to pyelonephritis.
There are also alterations in the tubular handling of wastes and nutrients. As in the non-pregnant state, glucose is freely filtered in the glomerulus. During pregnancy, the reabsorption of glucose in the proximal and collecting tubule is less effective, with variable excretion.
In normal pregnancies the total protein concentration in urine does not increase above the upper normal limit. Arterial under-filling in pregnancy leads to the stimulation of arterial baroreceptors, activating the RAA and the sympathetic nervous systems.
These changes lead to sodium and water retention in the kidneys and create a hypervolaemic, hypoosmolar state characteristic of pregnancy. The increase in plasma volume plays a critical role in maintaining circulating blood volume, blood pressure and uteroplacental perfusion during pregnancy. Activation of the RAA system leads to increased plasma levels of aldosterone and subsequent salt and water retention in the distal tubule and collecting duct.
In addition to the increased renin production by the kidneys, ovaries and uteroplacental unit produce an inactive precursor protein of renin in early pregnancy. Plasma levels of aldosterone correlate well with those of oestrogens and rise progressively during pregnancy.
The increase in aldosterone is responsible for the increase in plasma volume during pregnancy. The rise in GFR also increases distal sodium delivery, allowing excretion of excess sodium. Progesterone has antikaliuretic effects and therefore excretion of potassium is kept constant throughout pregnancy due to changes in tubular reabsorption, and total body potassium increases during pregnancy.
Hypothalamic AVP release increases early in pregnancy as a result of increased relaxin levels. AVP mediates an increase in water reabsorption via aquaporin 2 channels in the collecting duct. The threshold for hypothalamic secretion of AVP and the threshold for thirst is reset to a lower plasma osmolality level, creating the hypo-osmolar state characteristic of pregnancy.
These changes are mediated by human chorionic gonadotropin hCG and relaxin. In middle and late pregnancy there is a four-fold increase in vasopressinase, an aminopeptidase produced by the placenta. These changes enhance the metabolic clearance of vasopressin and regulate the levels of active AVP.
In conditions of increased placental production of vasopressinase, such as pre-eclampsia or twin pregnancies, a transient diabetes insipidus may develop. The levels of natriuretic peptides are higher in pregnant women with chronic hypertension and pre-eclampsia. There is a significant increase in oxygen demand during normal pregnancy.
A mild fully compensated respiratory alkalosis is therefore normal in pregnancy arterial pH 7. Inspiratory reserve volume is reduced early in pregnancy, as a result of increased tidal volume, but increases in the third trimester, as a result of reduced functional residual capacity see Fig.
Pregnancy may also be accompanied by a subjective feeling of breathlessness without hypoxia. Classically, the breathlessness is present at rest or while talking and may paradoxically improve during mild activity. The exact underlying mechanism is not clear but pregnancy-associated hormones such as human chorionic gonadotropin hCG , oestrogen and progesterone could to be involved in the aetiology.
Thyroid hormones may also be involved in the development of nausea symptoms, as a strong association with nausea and abnormal thyroid function tests has been found. About 0. As pregnancy progresses, mechanical changes in the alimentary tract also occur, caused by the growing uterus.
The stomach is increasingly displaced upwards, leading to an altered axis and increased intra-gastric pressure. The oesophageal sphincter tone is also decreased and these factors may predispose to symptoms of reflux, as well as nausea and vomiting. Changes in oestrogen and progesterone levels also influence the structural alterations in the gastrointestinal tract.
These include abnormalities in gastric neural activity and smooth muscle function, leading to gastic dysrhythmia or gastroparesis. The alterations are pronounced in women with pre-existing gastrointestinal diseases such as gastroesophageal reflux disease, diabetic gastroparesis, gastric bypass surgery or inflammatory bowel disease. There is an increase in the production of thyroxine-binding globulin TBG by the liver, resulting in increased levels of thyroxine T 4 and tri-iodothyronine T 3.
Serum free T 4 fT 4 and T 3 fT 3 levels are slightly altered but are usually of no clinical significance. Levels of free T 3 and T 4 do however decrease slightly in the second and third trimesters of pregnancy and the normal ranges are reduced. Serum concentrations of TSH are decreased slightly in the first trimester in response to the thyrotropic effects of increased levels of human chorionic gonadotropin. Levels of TSH increase again at the end of the first trimester, and the upper limit in pregnancy is raised to 5.
Pregnancy is associated with a relative iodine deficiency. The causes for this are active transport of iodine from the mother to the foeto-placental unit and increased iodine excretion in the urine. Three types of steroids are produced by the adrenal glands: mineralocorticoids, glucocorticoids and sex steroids. The RAA system is stimulated due to reductions in vascular resistance and blood pressure, causing a three-fold increase in aldosterone levels in the first trimester and a fold increase in the third trimester.
During pregnancy there is also an increase in serum levels of deoxycorticosterone, corticosteroid-binding globulin CBG , adrenocorticotropic hormone ACTH , cortisol and free cortisol. These changes cause a state of physiological hypercortisolism and may be clinically manifested by the striae, facial plethora, rising blood pressure or impaired glucose tolerance.
After the birth of the fetus, the uterus contract further, resulting in the separation and delivery of the placenta. Maternal total serum calcium decreases due to maternal hypoalbuminemia , but the ionized calcium levels are maintained. The body's posture changes as the pregnancy progresses. Dilation of the cervix is now 1. This can cause dizziness or loss of consciousness. Prior to delivery, the cervix dilates significantly, softens, and thins, allowing the baby to pass through the birth canal. The plasma cells produce the secretory IgA , that provide the newborn his first passive immune defence.
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The composition of mucus secreted by cervical glands vary under the influence of ovarian hormones during menstrual cycle. The blockage of the openings of the mucosal glands by the stiff mucus causes the formation of dilated cyst called Nabothian cyst.
The cervical endometrium lacks spiral arteries. During the menstrual cycle, the cervical endometrium undergoes only insignificant changes, and it is not sloughed off during menstruation. Vaginal portion of the cervix the ectocervix is lined by nonkeratinized stratified squamous epithelium. The female external genitalia consist of the labia majora , labia minora , the clitoris and glands opening into the vestibulum vaginae.
The labia minora are composed of the loose connective tissue with elastic fibers and contains a lot of adipose tissue. The surface is lined by stratified squamous epithelium with the thin layer of keratinized cells. Large sebaceous and sweat glands are present.
The labia majora are also composed of loose collagenous connective tissue with a thin layer of smooth muscle cells. The surface is covered by skin. The outer surface is thicker and contains pubic hair, sebaceous glands and sweat glands eccrine and apocrine.
The inner surface is thinner and also contains sebaceous and sweat glands. The clitoris is covered by stratified squamous keratinized epithelium. It is composed of two small erectile bodies corpora cavernosa. They are homologous to the male bulbourethral glands. Histological structure and visual aspect of breast naturally vary according to the age and functional state of the gland. This is micrograph of an HE-stained inactive mammary gland.
Try to compare it with the following slide, which shows an active mammary gland during lactation, also stained by HE.
The mammary gland is composed of 20 tubuloalveolar glandular lobes separated by dense collagenous connective tissue and adipose tissue. In the axis of each glandular lobe is the lactiferous duct ductus lactifer which is about 2 cm to 4 cm long and opens into the nipple. The lactiferous duct is lined by two layers of cuboidal or columnar epithelium with myoepithelial cells. Into these lactiferous ducts open the interlobular ducts lined by simple cuboidal epithelium.
In the inactive gland before puberty consists the mammary gland chiefly of the lactiferous duct elements and few lobular branches. It is exactly the presence of secretory lobules, which defines the structure of mature mammary gland. Lobules are surrounded by loose connective tissue with lymphocytes and plasma cells. Morphological growth is caused by accumulation of adipose tissue and collagen connective tissue due to the increased level of estrogens during puberty.
If the pregnancy occurs, the elongation and branching of the terminal ductules appear. From the growing ends of the terminal ductules differentiate alveoli surrounded by 4 to 6 myoepithelial cells. The lining epithelial cells of alveoli differentiate into active secretory cells with prominent rough endoplasmic reticulum, Golgi apparatus and numerous mitochondria.
The growth during pregnancy is affected by many factors, in the first place by hormones — estrogens , progesterones , prolactin , human chorionic gonadotropin — hCG. The breast milk is produced by epithelial alveolar secretory cells.
It is stored in lumen of alveoli and in lumen of lactiferous ducts. In the cytoplasm of secretory cells are prominent secretory granules containing proteins, chiefly lactalbumin and casein, released by merocrine secretion.
The plasma cells produce the secretory IgA , that provide the newborn his first passive immune defence. The myoepithelial cells are not degraded and they are used in the case of the next pregnancy. After menopause, the mammary gland involutes and individual parts atrophy. The nipple is covered by the stratified squamous keratinized epithelium. This epithelium contains melanocytes, which store the melanin especially during pregnancy. The stroma is composed of smooth muscle tissue, which is in the deeper layers oriented in the circular pattern around the lactiferous ducts.
Depending on the site, where these cyclic changes occur, can we distinguish several kinds of cycle — ovarian ovulation , uterine menstrual , cervical , vaginal. One ovarian cycle lasts about 28 days in length But it could average about 24 to 36 days. The ovarian cycle is divided into three phases:. It lasts between 12 to 14 days from the first day of the last menstrual bleeding. FSH produced from adenohypophysis stimulates one of the follicles to enlarge, mature and develop into the Graafian follicle.
This mature follicle bulges above the ovarian surface. In this phase, the follicle cells produce estrogens and a low level of progesterone. The Graafian follicle ruptures and the ovum is released into the peritoneal cavity, where is caught by fimbriae of uterine tube. After the release of the ovum, the remains of follicle convert into the corpus luteum which produces progesterone and prepares the reproductive organs for pregnancy.
The menstrual cycle is the complex of cyclic endometrial changes. It repeats periodically each 28 days. During this cycle, the endometrium undergoes significant morphologic and functional changes. These changes are caused by effect of ovarian hormones estrogens and progesterone which are controlled by adenohypophysis. The beginning of the menstrual cycle is defined as the first day of the menstrual bleeding. The menstrual cycle is divided into four phases:. It lasts the first four days of the cycle.
If fertilization does not occur, the corpus luteum ceases to produce progesterone after 14 days. The blood level of progesterone rapidly decreases. It causes the involution of the endometrium. The stratum functionale of endometrium is sloughed with 35 — 50 ml of menstrual blood. This phase is caused by effect of estrogens. It continues simultaneously with the follicle maturing the follicular phase of the ovarian cycle.
After the menstrual phase, the endometrium is reduced to the thin about 1 mm stipe of connective tissue lamina propria containing the basal portions of uterine glands and the lower parts of spiral arteries. The stratum functionale of endometrium regenerates, epithelial cells and cells of the connective tissue stroma proliferate and produce the collagen.
Spiral arteries lengthen — are slightly coiled and they reach only into the basal two thirds of the endometrium. At the end of this phase, the endometrium is about 3 mm thick, the glands are straight and they have prominent lumen. The secretory phase is induced by progesterone produced by the corpus luteum.
Progesterone stimulates glands to produce glycoproteins. The glands changes, become coiled and their lumen is widened due to the accumulated secretion. The epithelial cell begin to store glycogen. In this phase, the endometrium is about 5 mm to 6 mm thick. Mitosis are rare. The coiled arteries lengthen and they pervade to the surface of endometrium.
Now is the uterus prepared for implantation of fertilized ovum. This phase lasts only few hours. If there is no fertilization, corpus luteum degenerates and the production of progesterone ceases.
The contraction of mucosal arteries due to the decreased level of progesterone causes ischemia of endometrial cells and afterward, these cells degenerate. The secretion of sex hormones is under control of hypothalamic-pituitary axis. Gonadotropin-releasing hormone GnRH produced by hypothalamus stimulates hormonal secretion from adenohypophysis. Depending on hypothalamic stimulation, the adenohypophysis secrete two hormones :.
These hormones are important for development of the reproductive organs and induce the proliferative phase of the menstrual cycle.
It is responsible for the secretory phase of the menstrual cycle, decreases the uterine contractility during pregnancy, stimulates the growth of alveoli in mammary gland and increases the basal temperature. Just before we focus on the processes in the ovum, it is important to explain capacitation. It is the activation process of spermatozoa within the female reproductive system. Capacitation involves biochemical structural and functional changes to the sperm that result in the increased ability to penetrate the zona pellucida and fertilize the ovum.
Usually, only a few hundred of about to millions sperm in an ejaculate of spermatozoa reach the site of fertilization, typically the ampulla of the uterine tube. Sperm cells must penetrate the corona radiata and zona pellucida. Only one sperm cell penetrates the ovum. Before sperm cell can fertilize the ovum, it must undergo the process of capacitation.
In this process, the sperm cells acquire the ability to bind to zona pellucida receptors. Binding to these receptors on the zona pellucida triggers the acrosome reaction in which enzymes are released from the acrosome and enable sperm cell to penetrate the zona pellucida.
At the same time, the the cortical reaction zona reaction is initiated. The releasing of cortical granules containing proteases causes inactivation of zona pellucida receptors.
That prevents the fusion of multiple sperms with on ovum polyspermy. The impregnation of the oocyte induce termination of the second meiotic division. The result of fertilization is restoration of a diploid complement of 46 chromosomes , embryonal sex determination sperm cell with the Y chromosome determines male and the X chromosome determines female , and the beginning of cleavage. During the fertilization the fusion of gametes , the zygote is formed. Zygote contains a diploid complement of chromosomes.
As it passes through the uterine tube into the uterine cavity, the zygote undergoes cleavage — blastogenesis. It comprises of series of mitotic divisions without cell growth, resulting in a rapid increase in the cell number. These individual cells — blastomeres — become smaller while their number increases. The human embryo formed by 12 to 15 blastomeres is called a morula.
The morula arises during the third day after fertilization and it enters into the uterus. If the uterus is prepared, the morula is caught and embedded in the uterine mucosa — implantation.
During 4th day after fertilization, the fluid-filled cavity is formed in the centre of the morula. This cavity blastocyst cavity defines the beginning of the blastocyst. Blastocyst cavity begins enlarge and divides the cell mass into two parts:. At the end of the first week is the blastocyst superficially embedded in the endometrium. Human pregnancy lasts about days it averages between and days. It is counted from the first day of the last menstrual cycle. The gravidity is divided into three trimesters.
The term birth partus maturus is defined as delivery of a baby between 38 and 42 weeks of gestation. Partus praematurus preterm birth is birth of a baby of less than 37 weeks of gestation. The first sign of pregnancy is often the amenorrhea — the absence of menstrual period. But gravidity can also be accompanied by minor periodic bleeding.
The certain sign is a positive test result for human chorionic gonadotropin hCG. It is a glycoprotein produced by syncytiotrophoblast. The pregnancy tests are based on hCG detection in the maternal blood or urine and they can recognize the concentration of hCG from 7th or 8th day after fertilization.
The identification of embryo by using vaginal ultrasonography is possible in about 4th week of pregnancy. From the 6th week can be also by using USG recognized the embryonic heart action. The gestational also called menstrual age of pregnancy means that the the initiation of pregnancy is the first day of the last normal menstrual period LMP.
Nevertheless, the fertilization occurs about two weeks later after ovulation. The fetal age also called embryonal is the actual biological age of embryo counting from the time of fertilization and it is used especially by embryologists. In the gynaecological terminology is preferred the gestational age counted in weeks. The relation between fetal embryonal and gestational age:.
The calculation of the birth term:. For example: the first day of the last menstrual period was 3. The retained fluid is eliminated with urine in the first days after delivery. Before the actual delivery, the lie , presentation and holding of the fetus are defined.
Even today in the age of ultrasounds, every obstetrician should be able to describe this using an external palpation of pregnant woman. There are 3 types of fetal lies — longitudinal long axis of the fetus is parallel to the long axis of the uterus , transverse and oblique. However, only longitudinal lie can be spontaneously delivered. The others are delivered surgically or manually turning the fetus into the longitudinal lie.
The labour itself is divided into four phases or periods of delivery in some literature, only three phases are distinguished — the last phase is not separated. During the first phase of labour, the cervix is shorten and dilated. This phase is the longest period of labour. It takes about 12 to 14 hours in nulliparous woman women giving birth for the first time and hours in women who have already given birth.
In the end of pregnancy, the cervix becomes soft and pliable, allowing the dilatation during contractions. The entire phase lasts a few minutes. The second period of delivery significantly facilitated by the episiotomy. Episiotomy can be distinguished into lateral oblique cutting line or median cutting line toward the rectum. Episiotomy must be performed during contraction.
Decision whether to proceed episiotomy or not depends on consideration of the obstetrician with consideration of the birth process and monitored status of the fetus see below. The physiological movements of the fetus during pass through the small pelvis are: progression of head , flexion of head , internal rotation , deflection , external rotation , followed by delivery of arms.
The amount of its muscle, connective and elastic tissue, blood vessels, and nerves increases. Its shape changes from elongated to oval by the second month, to round by midgestation, then back through oval to elongated at term the end of a normal nine-month pregnancy.
The uterus softens beginning at the sixth week. It changes position as it increases in size, ascending into the abdomen by the fourth month and eventually reaching to the liver. You may feel these contractions in the last weeks of pregnancy, when they are known as false labor. Other parts of the reproductive system change along with the uterus.
The cervix and vagina have an increased blood supply, which causes a darkening in color apparent by the sixth week. The amount of elastic tissue increases to prepare the way for the stretching that will be required during delivery. Secretions increase, and a mucous plug develops in the cervix. The fallopian tubes, ovaries, and ligaments supporting the uterus all enlarge and elongate. The ovaries, of course, cease to ovulate. During the fourth month, the uterus grows into the abdomen, causing the abdominal wall to expand to accommodate it.
The connective and elastic tissues stretch and straighten, creating thinned areas called striae stretch marks. While the red of the striae may fade, silver remnants usually remain after delivery. In 50 percent of women, striae develop in the third trimester.
Maternal physiological changes in pregnancy - Wikipedia
Hormones are signalling chemicals produced in the body, which circulate in the blood. Different hormones control or regulate the activity of different cells or organs. In this study session, you will learn about some of the changes that occur during pregnancy in the uterus, cervix and vagina, the cardiovascular system, gastrointestinal system, and urinary system, and about changes in the breasts and skin.
You will also learn about the implications of all these changes for you as a health worker managing the health of pregnant women. SAQs 7. In Study Sessions 3, 4 and 5 you learned about the main female reproductive hormones, oestrogen and progesterone, and their functions in preparing the uterus for pregnancy.
Oestrogen and progesterone are also the chief hormones throughout pregnancy. During pregnancy, oestrogen promotes maternal blood flow within the uterus and the placenta. You learned about this in Study Session 5. Among other effects, high levels of progesterone cause some internal structures to increase in size, including the uterus, enabling it to accommodate a full-term baby.
It has other effects on the blood vessels and joints, which we will discuss later in this study session. After conception, the uterus provides a nutritive and protective environment in which the fetus will grow and develop. It increases from the size of a small pear in its non-pregnant state to accommodate a full-term baby at 40 weeks of gestation. The tissues from which the uterus is made continue to grow for the first 20 weeks, and it increases in weight from about 50 to 1, gm grams.
By the time the pregnancy has reached full term, the uterus will have increased to about five times its normal size:. The uterus may drop slightly as the fetal head settles into the pelvis, preparing for delivery. Notice the position at 40 weeks of gestation, which is shown as a dotted line in Figure 7. The cervix remains 2.
In late pregnancy, softening of the cervix occurs in response to increasing painless contractions of its muscular walls. You will learn all about this in the next Module on Labour and Delivery Care. Her abdomen transforms from flat or concave dished to very convex bulging outwards , increasing the curvature of her back.
As a result, many pregnant women get back pain. Too much standing in one place or leaning forward can cause back pain, and so can hard physical work. You will learn how to identify kidney infections in Study Session In addition, progesterone causes a loosening of ligaments and joints throughout the body. Pregnant women may be at greater risk of sprains and strains because the ligaments are looser, and because their posture has changed.
Continuing weight increase in pregnancy is considered to be one favourable indication of maternal adaptation and fetal growth. However, routine weighing of the mother during pregnancy is not now thought to be necessary, because it does not correlate well with pregnancy outcomes.
The expected increase in weight of a healthy woman in an average pregnancy, where there is a single baby, is as follows:. She will also require a higher calorie diet.
You will learn a lot about diet and healthy nutrition in pregnancy in Study Session 14 of this Module. A lack of significant weight gain may not be a cause for concern in some women, but it could be an indication that the fetus is not growing properly.
Doctors and midwives may refer to this as intrauterine growth restriction IUGR of the fetus. The cardiovascular system consists of the heart, the blood vessels veins and arteries , and the blood that circulates around the body. It is the transport system that supplies oxygen and nutritive substances absorbed from the gastrointestinal tract to all the cells, tissues and organs of the body, enabling them to generate the energy they need to perform their functions.
It also returns carbon dioxide, the waste product of respiration, to the lungs, where it is breathed out. The chemical processes that go on in the body generate many waste products, which the blood transports to the kidneys and liver, where they are removed. Other functions of the cardiovascular system include the regulation of body temperature, and the circulation and delivery of hormones and other agents that regulate body functions.
There are several significant changes in this complex system during pregnancy. Because it has to pump blood through the placenta, fetus and the much larger uterus and abdomen of the pregnant woman.
The amount of blood that is pumped out of the heart each minute is called the cardiac output. Table 7. A higher circulating blood volume is required to provide extra blood flow through the placenta, so nutrients and oxygen can be delivered to the fetus. The increase in blood volume is caused by two changes:. The volume of blood plasma increases after about the sixth week of pregnancy. Red blood cells contain the oxygen-carrying substance called haemoglobin, which is rich in iron see Box 7.
Iron is present in all cells and has several important functions, including oxygen transport and storage in the human body. It is the critical component of the oxygen-carrying substance haemoglobin , found in all red blood cells. It is the iron in haemoglobin that makes these cells appear red. If the diet is too low in iron, the person cannot make enough red blood cells. Iron is also involved in the storage and release of oxygen in the muscles.
Too little iron in the diet is the leading cause of anaemia. The measurement of haemoglobin is expressed using its chemical symbol Hb , and its weight in grams gm per decilitre dl of blood.
A decilitre equals 10 millilitres ml. Although there is a constant increase in the number of red blood cells in the circulation during pregnancy, the increase in the volume of blood plasma is much larger. This effect is referred to as physiological anaemia. It explains why iron in the diet, or from iron tablets, is so important during pregnancy. We said earlier that progesterone causes the ligaments and joints to loosen during pregnancy.
It also acts with some other natural chemicals in the body to cause the muscular walls of the blood vessels to relax slightly. The result is that there is less resistance to the flow of blood around the body, because the same volume of blood is circulating in slightly wider blood vessels.
Lower blood pressure is particularly common in early pregnancy. Many women report occasionally feeling dizzy in the first trimester, because less blood and less oxygen is being pumped to the brain.
Progesterone can also cause a sudden larger relaxation in the blood vessels, resulting in an acute feeling of dizziness, or even a brief loss of consciousness passing out. Another cause of dizziness can result from lying flat on the back. When a pregnant woman is lying flat on her back, the weight of her uterus and its contents compresses the large blood vessel vena cava leading from her lower body to the heart. When this blood vessel is squashed, the blood flow back to the heart is reduced, which in turn leads to a reduction in the blood flow out of the heart to the rest of the body.
Lying flat on her back can result in a sudden and dramatic drop in blood pressure, and dizziness or loss of consciousness may occur because not enough oxygen is reaching her brain. The weight gain in pregnant women increases the workload on the body from any physical activity. Steady, non-violent exercise is good for the mother because it prepares her body for labour Figure 7.
A pregnant woman should not do exercises where she is lying on her back, due to the compression of the major blood vessels returning blood to her heart. Strong exercise may lead to decreased blood flow to the uterus because blood is diverted to the muscles, but this has not been shown to have any long-term effects on the baby. Pregnant women should not exercise vigorously in hot weather, or if it makes them breathless, or if there are known risk factors such as a history of miscarriage.
If a pregnant woman experiences severe oedema, including swelling of the face, this is a danger sign that requires immediate referral to the nearest health facility. Fluid often collects in the tissues of the legs and feet of pregnant women after the first trimester, instead of being absorbed into the blood circulation. The swelling caused by this collection of fluid is called oedema.
It is a common condition in pregnant women, particularly if they stand for a long time during the day. Oedema of the hands may also occur. Advise the woman to rest frequently and to elevate raise her feet and legs while sitting. This will improve the return of blood to her heart and decrease swelling of the legs.
During pregnancy, many women find they get short of breath cannot breathe as deeply as usual. But if a woman is also weak and tired, or if she is short of breath all of the time, she should be checked for signs of sickness, heart problems, anaemia or poor diet.
Get medical advice if you think she may have any of these problems. As you may remember from your high school biology, food and fluids enter the gastrointestinal system in the mouth, pass through the oesophagus, stomach and intestines, and solid waste exits at the anus.
Proteins, fats and carbohydrates in our diet are broken down digested in the gut into units small enough to be absorbed from the intestines into nearby blood vessels. It is also the route by which nutritious substances, such as vitamins and minerals, enter the body.
During pregnancy, the muscles in the walls of the gastrointestinal system relax slightly, and the rate at which food is squeezed out of the stomach and along the intestines is slowed down.
Can you think of a reason why slowing down the passage of food through the gastrointestinal system might be beneficial in pregnancy? It increases the time available for digestion, and it maximises the absorption of nutrients from the diet. Undesirable effects also result from slow emptying of the stomach, and slow movement of food through the gut. Many women also have nausea in the first months of pregnancy. This is not dangerous and usually goes away after the birth.
If the mother has difficulty with nausea or indigestion, advise her to eat small, frequent meals. The mother should not lie down flat for 1 to 2 hours after eating, because this may cause these symptoms. The urinary system consists of the kidneys a pair of organs on either side of the abdomen near the back , the tubes connecting the kidneys to the bladder where urine is stored, and a tube called the urethra that passes urine out of the body.
Look back at Figure 3. The kidneys extract waste from the blood and turn it into urine. Therefore, there is also an increase in the amount of urine produced during pregnancy. Needing to urinate pee often is normal, especially in the first and last months of pregnancy.
This happens because the growing uterus presses against the bladder.