The Physical And Physiological Changes Of Pregnancy

The Physical And Physiological Changes Of Pregnancy

1. The Physical And Physiological Changes Of Pregnancy DR.HAFSA IMTIAZ (DPT)

2. THE PHYSICAL AND PHYSIOLOGICAL CHANGES OF PREGNANCY The changes of pregnancy are chiefly the direct result of the interaction of four factors: the hormonally mediated changes in collagen and involuntary muscle the increased total blood volume with increased blood flow to the uterus and the kidneys the growth of the foetus resulting in consequent enlargement and displacement of the uterus the increase in body weight and adaptive changes in the centre of gravity and posture Hafsa Imtiaz 2

3. Endocrine System The changes of pregnancy are orchestrated by hormones: Progestrone Estrogen Relaxin . Hafsa Imtiaz 3

4. Progestrone . Progesterone is produced first by the corpus luteum reaches a maximum of about 30mg per 24 hours at about 10 weeks of pregnancy and thereafter declines, then by the placenta, increasing production from about 10 weeks, which at first supplements that from the corpus luteum and then completely takes over the role. Three progestogens are produced in the placenta but the chief one is progesterone. Hafsa Imtiaz 4

5. ROLE OF PROGESTRONE 1. Reduction in tone of smooth muscle: (a) food may stay longer in the stomach; peristaltic activity is reduced (b) water absorption in the colon is increased leading to tendency to constipation (c) uterine muscle tone is reduced; uterine activity is damped down (d) detrusor muscle tone reduced (e) dilatation of the ureters favouring urine stasis with elongation to accommodate the increasing size of the uterus; this may contribute to the likelihood of urinary tract infections (f) urethral tone reduced, which may result in stress incontinence (g) reduced tone in the smooth muscle of the blood vessel walls leading to dilation of blood vessels, lowered diastolic pressure. Hafsa Imtiaz 5

6. CONT….. 2. Increase in temperature (0.5–1°C). 3. Reduction in alveolar and arterial PCO2 tension, hyperventilation 4. Development of the breasts’ alveolar and glandular milk-producing cells. 5. Increased storage of fat. Hafsa Imtiaz 6

7. ESTROGEN Oestrogens are produced first by the corpus luteum and then by placenta Several estrogens are produced by placenta but oestriol produced in excessive quantities and excreted in maternal urine and amount of it excretion indicates well being of fetus. foetal adrenal glands and the foetal liver also contribute towards oestrogen synthesis in pregnancy Hafsa Imtiaz 7

8. Effects Of Estrogen Increase in growth of uterus and breast ducts. Increasing levels of prolactin to prepare breasts for lactation; oestrogens may assist maternal calcium metabolism. May prime receptor sites for relaxin (e.g. pelvic joints, joint capsules, cervix). Increased water retention, may cause sodium to be retained. Higher levels result in increased vaginal glycogen, predisposing to thrush. Hafsa Imtiaz 8

9. Relaxin Relaxin is produced in the theca and luteinised granulosa cells in the corpus luteum and later in decidua . relaxin might have a role relating to continence in pregnancy. Research suggests that it is produced as early as 2 weeks of gestation It is at highest levels in the first trimester, and then drops by 20% to remain steady Hafsa Imtiaz 9

10. Effects Of Relaxin Gradual replacement of collagen in target tissues (e.g. pelvic joints, joint capsules, cervix) with a remodelled modified form that has greater extensibility and pliability. Collagen synthesis is greater than collagen degradation and there is increased water content, so there is an increase in volume. Inhibition of myometrial activity during pregnancy up to 28 weeks when women become aware of Braxton Hicks contractions. May have a role in the remarkable ability of the uterus to distend and in the production of the necessary additional supportive connective tissue for the growing muscle fibres . Hafsa Imtiaz 10

11. Cont…. Rising levels of relaxin effect softening of the collagenous content of the cervix Towards the end of pregnancy. May have a role in mammary growth. Affects relaxation of the pelvic floor muscles Hafsa Imtiaz 11

12. Reproductive system changes Amenorrhoea is one of the first signs of pregnancy for most women. Other changes include: Cervical Uterine Hafsa Imtiaz 12

13. Cervical Changes Cervix will be seen to have changed in colour from pink to a bluish shade. Cervix first increase in depth, In late pregnancy ripening of cervix occur, involves the softening, greater distensibility , effacement and eventually dilation of the cervix are produced by the endocrine-controlled restructuring of collagen and other tissues As pregnancy progresses a plug of thick mucus forms in the cervical canal, sealing the uterus Hafsa Imtiaz 13

14. Bishop’s score The Bishop Score (also known as Pelvic Score) is the most commonly used method to rate the readiness of the cervix for induction of labor. The Bishop Score gives points to 5 measurements of the pelvic examination dilation, effacement of the cervix, station of the fetus, consistency of the cervix, and position of the cervix  If the Bishop score is  8 or greater the chances of having a vaginal delivery are good  and the cervix is said to be f avorable or "ripe" for induction.    If the Bishop score is  6 or less  the chances of having a vaginal  delivery are low  and the cervix is said to be u nfavorable or "unripe" for induction. Hafsa Imtiaz 14

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16. UTERINE CHANGES The growing uterus rises out of the pelvis to become an abdominal organ at about 12 weeks’ gestation displacing the intestines and coming to be in direct contact with the abdominal wall as pregnancy proceeds. in the final 2–3 weeks the fundal height drops particularly noticed by the primigravida . because the foetal head has entered the pelvic inlet which may cause an increased frequency of micturition Hafsa Imtiaz 16

17. CONT…… head will be said to be ‘engaged’ when its greatest diameter has passed through the brim of the pelvis At the end of pregnancy abdominal palpation is used to determine how much of the foetal head remains above the pelvic brim This is estimated in fifths or by using the terms ‘unengaged’, ‘engaging’, ‘engaged’ Hafsa Imtiaz 17

18. CONT……. Hafsa Imtiaz 18

19. CONT…… With increase In uterus size, blood supply also increases. The weight of the uterine tissue itself increases from about 50g to 1000g at term The collagenous tissue increases in area and elasticity through pregnancy under hormonal influence. The muscle fibres of the fundus and body increase in length and thickness throughout pregnancy to accommodate the growing foetus . Hafsa Imtiaz 19

20. CONT…… As pregnancy progresses the isthmus develops to become the lower uterine segment by term it accounts for approximately the lower 10cm of the uterus above the cervix. musculature is not highly developed in this area and towards term it becomes soft and stretchy, allowing the foetus to sink lower in the uterus and into the true pelvi Hafsa Imtiaz 20

21. Braxton Hicks Contraction Braxton Hicks contractions are painless sporadic contractions and relaxation of the uterine muscle. Sometimes, they are referred to as prodromal or “false labor" pains. Occur because Uterine muscle fibres activity increases and coordinated contractions occur by 20 th week of gestation. they facilitate the blood flow through the placental site and play a part in the development of the lower uterine segment Braxton Hicks contractions are thought to play a role in toning the uterine muscle in preparation for the birth process. Occur when fetus is stressed and need increased blood flow to placenta to provide fetal oxygenation, triggers may include, when the woman is very active, when the bladder is full, following sexual activity, and when the woman is dehydrated. some women experience considerable sequences of contractions of variable length 20 seconds to 4 minutes. Hafsa Imtiaz 21

22. Cardiovascular system Blood volume increases by 40% or more to cope with: increasing requirements of the uterine wall with the placenta weight gain supplying the greater bulk increased power needed to move it DILUTION ANAEMIA Also known as physiological anemia of pregnancy Plasma concentration increses and consequentaly hemoglobin level falls to about 80% One of the cause of tierdness and malaise experienced by women in early pregnancy Hafsa Imtiaz 22

23. CONT……. Progesterone acts on the smooth muscle of blood vessel walls to produce slight hypotonia , and causes a small rise in body temperature; therefore pregnant women generally have a good peripheral circulation and do not feel the cold. The heart size increases and accommodate more blood so: stroke volume rises cardiac output increases by 30–50% there is a progressive small increase in heart rate through pregnancy Hafsa Imtiaz 23

24. CONT…… Blood pressure may even fall a little through the second trimester of pregnancy, so women may easily feel faint from prolonged standing pregnancy hypotensive syndrome: In the third trimester the weight of the foetus may compress the aorta and inferior vena cava against the lumbar spine when the woman is lying supine, causing dizziness and even unconsciousness varicose veins particularly in the legs and gravitational oedema occur due to: Slight vascular hypotonia , downward pressure of the enlarging uterus, weight gain, raised intra-abdominal pressure, and progesterone and relaxin -mediated changes in collagen Hafsa Imtiaz 24

25. CONT…. Varicosities of the vulva and anus ( haemorrhoids , piles) may also occur. Oestrogens may be responsible for fluid retention in body tissues. Some women can no longer wear hard contact lenses because their eye shape changes symptoms such stuffy’ nose and increased vaginal discharge can be observed As a result of the increased peripheral circulation and hormonal stimulation, the mucous membranes (e.g. nasal, vaginal) become more active and lush Consequently prolongation of coughs and colds may be experienced, also nose bleeds and vaginal thrush Hafsa Imtiaz 25

26. Respiratory system EFFECTS ON VENTILATION Slight increase in ventilation occur due to: increased circulating progesterone levels in pregnancy further sensitise the respiratory centre in the medulla to carbon dioxide increasing demand for oxygen resting respiratory rate goes up a little, from about 15 to about 18 breaths per minute, and there is a lowering by some 2% of the maternal blood carbon dioxide tension Hafsa Imtiaz 26

27. Cont…. Hafsa Imtiaz 27 EFFECTS ON VOLUMESAND CAPACITIES Tidal volume increases gradually by up to 40%, and alveolar ventilation also rises Vital capacity remains same while expiratory reserve reduces EFFECTS ON DIAPHRAGM: By the third trimester, enlarging uterus increasingly impedes the descent of diaphgram Towards term it may actually displace the diaphragm upwards, often by 4cm or more where the foetus is large or the abdominal component of the maternal torso is short, or both

28. CONT… ON RIBS CAGE The upward pressure of the foetus causes rib flaring Maternal lower costal girth is increased, often by as much as 115cm, as is the subcostal angle Because of this the respiratory excursion is limited at the lung bases and greater movement is observed in the mid-costal and apical regions women frequently experience considerable breathlessness on even modest exertion towards the end of the pregnancy. hormone relaxin softens the costochondral junctions and renders them more mobile Women complain of costal margin pain or rib ache, and of the foetus kicking the diaphragm and ribs Hafsa Imtiaz 28

29. Breast As early as 2–4 weeks of pregnancy: unusual tenderness and tingling may be experienced in the breasts enlargement begins soon, with the breasts becoming nodular and lumpy. The rise in oestrogens is responsible for the growth of the duct system The rise in progesterone is responsible for growth of the alveoli total breast weight increases to about 400–800g blood supply increases number, size and complexity of the ducts increases At about 8 weeks, sebaceous glands in the pigmented area around the nipples become enlarged and more active, appearing as nodules The sebum secreted assists the nipple to become softer and more pliable Hafsa Imtiaz 29

30. CONT……. Hafsa Imtiaz 30 By 12 weeks of pregnancy the nipples and an area around them become more pigmented due to the stimulation of melanin production by the anterior pituitary remain as for 12 months after parturition. In 12th week a little serous fluid may be expressed from the nipples by about the 16th week colostrum can be expressed. Human milk ‘comes in’ about the 3rd or 4th postpartum day

31. SKIN darkening of the skin of the vulva, nipples and face chloasma ’ or the ‘mask of pregnancy: blotches which sometimes occur on the forehead and cheeks pigmentation may also form a dark line in the skin overlying the linea alba Striae or ‘stretch marks’ can develop over buttocks, abdomen and breasts and may become pigmented There is an increase in blood flow to the skin, which increases the activity of sebaceous and sweat glands, and so increases evaporation Fat is laid down, on the thighs, upper arms, abdomen and buttocks, in the second and third trimesters, act as: store which is subsequently called on in breastfeeding, provided a woman does not ‘eat for two’ in the puerperium Hafsa Imtiaz 31

32. Gastrointestinal system Hafsa Imtiaz 32 Nausea and vomiting, thought now to be the response of some to HCG can be aggravated by certain foods, even by their odours , and by iron tablets if inappropriately managed leads to Hyperemesis gravidarum   characterized by severe nausea, vomiting, weight loss, and possibly dehydration. Feeling faint may also occur. gut musculature becomes slightly hypotonic and the motility is decreased leading to: Prolong gastric emptying time slower passage of food

33. CONT…. Delayed large bowl motility leads to: increased absorption of water and a consequent predisposition to constipation because the faeces are dry and hard Heart Burn or GERD occur due to: reduced speed of oesophageal peristalsis, hormonally mediated slackness of the cardiac sphincter, displacement of the stomach and an increased intra-abdominal pressure as pregnancy progresses There is softening and hyperaemia of the gums and bleeding may occur from minor trauma. Salivation may be increased. Hafsa Imtiaz 33

34. Nervous system Mood lability , anxiety, insomnia, nightmares, food fads and aversions, slight reductions in cognitive ability and amnesia are common in pregnancy. Water retention frequently causes unusual pressure on nerves, particularly those passing through canals formed of inelastic material like bone and fibrous tissue (e.g. the carpal tunnel), with resulting neuropraxia . Occasionally pregnant women complain of symptoms indicating traction on nerves, which can be due to increased weight, for example water retention in the arm increasing its weight and producing depression of the shoulder, and paraesthesia in the hand. Hafsa Imtiaz 34

35. Urinary System HCG hormone is present in urine early in pregnancy blood supply to the urinary tract in order to cope with the additional demands of the foetus for waste disposal increase in size and weight of the kidneys, and dilation of the renal pelvis vesicoureteral reflux: The musculature of the ureters is slightly hypotonic so that they are a little dilated, and also seem to elongate to circumvent the enlarging uterus Leading to pooling and stagnation of urine; this may predispose to urinary tract infections Hafsa Imtiaz 35

36. CONT…. As the pregnancy progresses the bladder changes position to become an intra-abdominal organ It is pressed upon and even displaced by the increasingly large and heavy uterus urethrovesical angle may be altered and the intra-abdominal pressure raised; the smooth muscle of the urethra may become slightly hypotonic, and supportive fascia and ligaments of the tract and pelvic floor may become more lax and elastic leading to urinary frequency in early pregnancy. Later in pregnancy there may be urge and stress incontinence Hafsa Imtiaz 36

37. Musculoskeletal system There is a generalized increase in joint laxity leading to increased joint range, which is hormonally mediated. Oestrogens , progesterone, endogenous cortisols and particularly relaxin seem to be responsible for this. the laxity is made possible by a gradual breakdown of collagen in the target tissue and its replacement with a remodelled modified form which has higher water content and which has greater pliability and extensibility. During pregnancy it is usually necessary for a woman to adapt her posture to compensate for her changing centre of gravity How a woman does this will be individual and will depend on many factors, including muscle strength, joint range, fatigue and role models The changing centre of gravity is chiefly made necessary by the distending abdomen Hafsa Imtiaz 37

38. CONT…… the lumbar and thoracic curves are increased the greater lumbar lordosis was due to an increase in the pelvic tilt about 50% of pregnant women experience back pain The increased body weight must result in more pressure through the spine, and increased torsional strains on joints. Women become clumsier and are inclined to trip and fall. These factors, together with joint laxity and fatigue (see p. 161), particularly in the first and third trimester, must make pregnant women more prone to injury Hafsa Imtiaz 38

39. Cont…… abdominal wall adapts to the required degree of distension The muscle fibres permit stretch, but the collagen components – the aponeurosis , fibrous sheaths and intersections, and the linea alba undergo hormonally mediated structural change to provide the necessary temporary extra extensibility. Diastasis recti can occur, that  is the partial or complete separation of the  rectus   abdominis in the third trimester there is increased water retention, which may result in a varying degree of oedema of ankles and feet reducing joint range Edema cause pressure on nerves, as in carpal tunnel syndrome, causes paraesthesia and muscle weakness affecting terminal portions of the median and ulnar nerve distributions. Hafsa Imtiaz 39

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