IRH - Physiology of Pregnancy Obstetric.pdf
- 1. PHYSIOLOGY OF PREGNANCY Miss Bwalya
- 2. DEFINITION • Pregnancy: It is a state of having a developing embryo or foetus within the body from conception to delivery of the baby. • The average duration of human pregnancy is 280days or 40weeks or 9 months counted from the first day of LMP • Physiology of pregnancy; refers to the adaptations during pregnancy that a woman undergoes to accommodate the growing embryo or fetus.
- 3. • Pregnancy causes physiological changes in all maternal organ systems. • Most organs return to normal after delivery. • In general, the changes are more dramatic in multi-fetal than in single pregnancies
- 4. IMPORTANCE OF PHYSIOLOGICAL CHANGES These physiological changes enable the woman to; ✓Maintain the pregnancy and accommodate the growing fetus. ✓Nourish the fetus during the period of development and growth ✓Provide the woman with strength and energy for delivery. ✓To prepare the woman’s body for lactation.
- 5. SYSTEMS AFFECTED BY THE PHYSIOLOGICAL CHANGES Although pregnancy occurs in the reproductive system other changes take place in the following systems: • Endocrine system • Cardiovascular system • Respiratory system • Urinary system • Gastrointestinal tract • Integumentary system (The skin) • Skeletal system • Nervous system
- 6. CHANGES IN ENDOCRINE SYSTEM • During pregnancy the hormones of reproduction increase both in number and amount than in non pregnant woman. • There is development of an extra endocrine gland which is the placenta. • The placenta produces the following hormone;
- 7. • Human Chorionic Gonadotrophin (HCG) ; it maintains the corpus luteum to continue secreting oestrogen and Progesterone until placenta takes over at 12 weeks. • This hormone is excreted in urine between 8- 12 weeks of gestation and is the hormone used to confirm pregnancy.
- 8. • Oestrogen and Progesterone; They promote growth of the uterus and keep the uterus sedated through pregnancy preventing premature onset of labour.
- 9. • Human placental lactogen (HPL); it regulates how the body uses fats and carbohydrates for energy. • Ensuring that there is glucose to the foetus. • It also makes the body less sensitive to insulin, thus allowing more glucose to be retained in the blood for nourishment of the foetus.
- 10. THE REPRODUCTIVE SYSTEM The uterus • The uterus is the organ which contains and nourishes the conceptus/foetus and therefore is the organ most affected by pregnancy. • During pregnancy oestrogen and progesterone cause the decidua to become thicker, richer more vascular at the fundus and in the upper body of the uterus. • The myometrium fibres increase in size (hypertrophy) and in number (hyperplasia).
- 11. • Uterus increase in wt. from 60g to 900g. It increases in size from 7.5x5x2.5 cm to 30x23x20 cm. • Blood supply to uterus increases to keep pace with its growth and to meet the needs of the functioning placenta. • The uterus changes to a globular shape causing pressure on other pelvic organs, and it no longer maintain the anteverted and anteflexed position
- 12. • During the eighth week of pregnancy the uterus develops Braxton hicks contractions. • These are painless contractions which bring about true contractions when the pregnancy gets to term. The uterine tubes • The uterine tubes together with the broad and round ligaments hypertrophy and become more vascular
- 13. The cervix • The cervix acts as an effective barrier against infections and it retains the pregnancy. • Under the influence of progesterone, endocervical cells secrete thick mucus called Operculum. • The operculum plugs the cervical os and provides protection from ascending infection. • Oestrogen increases cervical vascularity (blood supply).
- 14. • Due to the increase in blood supply the cervix changes from pink to dark purplish colour during pregnancy. • In late pregnancy softening of the cervix occurs in response to increasing painless contractions.
- 15. • In the later weeks of pregnancy the cervical canal becomes partly effaced in the lower uterine segment also as a result of braxton hicks contractions. • The ripening of the cervix and the effacement of the cervical canal prepares the cervix for labour.
- 16. Vagina • Oestrogen causes changes the surrounding connective tissues becomes more elastic. • This enables the vagina to distend or stretch during the second stage of labour and receiving the descending head. • There is increased blood supply to the vagina, which increases the production of vaginal discharge known as leucorrhoea (increased amount of normal whitish vaginal discharge).
- 17. • The epithelial cells interact with Doderlein’s Bacillus which is a normal vaginal flora and provide a more acidic environment in the vagina. • The acidic environment provides extra degree of protection against some infections while on the other hand increased susceptibility to other infections candidiasis.
- 18. The vulva • There is increased vascularity in the vulva causing a darkening in colour. • Varicosities (distended superficial veins) of the vulva veins may occur
- 19. Breast changes These occur due to increased blood supply to the breasts and effects of oestrogen • At 3 to 4 weeks - Prickling, tingling sensation • At 6 weeks – Breasts are enlarged and have a tense nodular feel • At 8 weeks - Subcutaneous veins are visible
- 20. • At 12 weeks – Nipples have enlarged and become more prominent. • The sebaceous glands in the primary areolar enlarge and become more prominent and are called Montgomery’s tubercles • At 16 weeks - Colostrum can be expressed, secondary areola appears
- 21. CARDIOVASCULAR SYSTEM The blood volume • Red Blood Cells (RBCs) increase in circulation in response to the extra oxygen requirements made by maternal and placental tissue. • Plasma volume increases by approximately 50% from the 10th week of pregnancy and reaches a maximum level by the 32nd to 34th week while cellular component is 30%.
- 22. • The increase in plasma results in haemodilution, which leads to lowered haemoglobin level and RBCs count. • This condition is referred to as Physiological anaemia. The haemodilution effect is most apparent at 32 – 34 weeks of gestation. • This level is maintained until the pregnancy reaches term
- 23. The heart • The increase in blood volume causes an increase in cardiac workload leading to increased size of heart. • Owing to the increasing pressure from the growing uterus the heart may be displaced upwards. • Cardiac output increases from 5 to 7 litres per minute in late pregnancy. This is effected by; – Increase in resting heart rate of about 15 bpm by the end pregnancy. – Increase in blood volume.
- 24. • Cardiac output increases by 30-50% (ejection /min) • Heart rate increase by 15% • Heart size increases by 12% by late pregnancy
- 25. Effects on blood pressure • Increased cardiac output is balanced by reduced peripheral resistance to prevent hypertension. • Arterial walls relax and dilate as progesterone acts on the smooth muscles.. • The majority of increased blood is directed to the uterus, of which 80% goes to the placenta. • Blood flow to the kidney increases by 30 – 50% in order to enhance excretion.
- 26. • Increased blood volume and peripheral vasodilatation may cause oedema of legs, anal and vulva areas, varicosities and haemorrhoids, especially in the 3rd trimester. • In later pregnancy supine position should be avoided as this causes hypotension to occur in 10% of pregnant women. • This is known as Supine Hypotensive Syndrome.
- 27. • This is caused by pressure of the enlarged uterus on the dilated inferior vena cava and abdominal aorta when a pregnant woman lies on her back for too long. • The uterus blocks the return of blood to the heart and results in the patient feeling faint, becoming pale and sweaty.
- 28. CHANGES IN THE URINARY SYSTEMS • Each kidney increase in length and weight. The renal pelvis and ureters dilate and lengthen due to the effects of progesterone • This causes urinary stasis that in turn increases the risk of infection and stone formation • Renal function increases due to increase plasma volume which in turn increases glomerular filtrate rate by 50%
- 29. Bladder • The bladder is displaced upward and anteriorly by enlarged uterus as a result it increases pressure leading to urinary urgency and frequency
- 30. Changes in the respiratory system • Changes in the respiratory system are necessary in order to maximize maternal oxygen intake. • As the increased size of the uterus displaces the diaphragm upwards and reduces lung surface area this causes an increase in respiration and laboured breathing. • In later pregnancy the ribs flare out to maintain the capacity of thoracic cavity by countering the effects of the enlarging uterus which presses upon the diaphragm.
- 31. • Nasal congestion occurs during pregnancy and is caused by increased vascularity, causing production of increased mucus.
- 32. Changes in the gastrointestinal system • There is increased salivation (ptyalism or sialorrhea) due to effects HCG and oestrogen. • Women often experience changes in their sense of taste, leading to dietary changes and food craving this is known as pica. • Nausea and vomiting occur mainly during early pregnancy, possibly due to raised oestrogen or HCG levels.
- 33. • Oestrogen exerts its effects on gums which makes them spongy and leads to bleeding during pregnancy. • Dental problems occur because of gingivitis rather than from dental carries • Progesterone relaxes smooth muscle, hence gastric emptying and peristalsis are slowed in order to maximize the absorption of nutrients.
- 34. • Constipation is common as a result of sluggish gut motility. • Undesirable effects also result from slow emptying of the stomach and reduced stomach acidity. • Heartburn is common and is associated with gastric reflux due to the relaxation of the cardiac sphincter.
- 35. • Carbohydrate metabolism is also altered. • The production of glucose from carbohydrates in maternal diet increases while glucose intolerance by the mother restricts its uptake or use. • This guarantees sufficient availability of glucose for the fetus as its primary source of energy for cellular metabolism.
- 36. Skin changes • Due to high hormone levels there is an increase in pigmentation during pregnancy. • Some women develop deeper, patchy colouring on the face called chloasma, commonly known as mask of pregnancy. • Linea nigra appears. This is a pigmented line running from the pubis to the umbilicus and sometimes higher.
- 37. • Striae gravidarum (red stripes) appear on the abdomen, breast , thighs and other areas due to stretching of collagen layer of the skin. • Increased blood supply to skin leads to sweating and women feel hotter in pregnancy as a result of increased levels of progesterone in circulation which lead to vasodilatation
- 38. Skeletal changes • The gait of the woman changes especially starting from the 2nd trimester; – Shoulders are drawn backwards. – Lumbar curve is increased further creating lordosis • Progesterone and relaxin cause relaxation of ligaments and muscles causing increased mobility of the joints particularly the pelvic joints.
- 39. • The relaxation allows the pelvis to increase its capacity in readiness to accommodate the fetal presenting part at the end of pregnancy and in labour. • These changes may give rise to discomfort and backache in advanced pregnancy
- 40. Maternal weight changes • There is an increasing weight gain during pregnancy. This is considered a favourable indicator. A pregnant woman is expected to approximately gain weight as follows; – 2.5 kg in the first 20 weeks – 0.5 kg per week until term – 12.0 – 12.5 kg approximate total
- 41. Psychological changes • Changes brought about as a result of pregnancy also affect the mind. • The woman experiences; depression, irritability, loss of appetite, feeling of great joy, love and responsibility. • Hostile feelings towards family members or towards pregnancy or the unborn child can all be within normal limit and depends upon the woman’s personality and her social circumstances
- 42. Diagnosis of pregnancy It is based on three groups of findings: • Symptoms experienced by the woman • Physical signs found on examination • Special investigations
- 43. Subjective (Presumptive) S&S of pregnancy • These signs and symptoms are subjective and non specific and could easily be caused by conditions unrelated to pregnancy. Amenorrhoea (absence of menstrual periods) • Amenorrhoea may also occur in times of emotional stress and change of environment, in hormonal disorders, anaemia or in women using contraceptives
- 44. Breast changes • From 3-4 weeks tingling of the breast and breast heaviness and enlargement may be the indication of pregnancy. • These symptoms may be experienced by non pregnant women prior to menstruation due to high hormonal levels
- 45. Morning sickness • More than 50% of pregnant women experience nausea and some vomiting between 4th – 14th week of pregnancy and usually occurs on rising up in the morning and is caused by high levels of HCG and oestrogen. • However nausea and vomiting could be due to non pregnant causes e.g cerebral irritation, malaria, gastritis etc.
- 46. Quickening • This is when the pregnant woman notices the first movements. • This occurs between 16 weeks in multigravida and between 20 weeks in primigravidas. • However, these intra abdominal movements could be due to increased peristalsis, flatus and abdominal muscle contractions.
- 47. Temperature elevation • This occurs when fertilization and implantation have taken place. • However an elevation in temperature could be due to almost any infection. Bladder irritation • Frequency of micturition without any signs of infection such as burning or pain often occur in early pregnancy. This can also occur in renal calculi and UTI
- 48. Objective (Probable) S&S of pregnancy Although the signs are more reliable than the presumptive S&S, non of them is conclusive as in many instances there are conditions rather than pregnancy which could give similar S&S a. Skin changes • Pigmentation of the skin often occurs in pregnancy and chloasm is usually noticed from the 16th week of pregnancy
- 49. b. Breast changes • From 8-12 weeks subcutaneous veins become noticed and there is an increase in the size and pigmentation of the nipple and areola and Montgomery's tubercles appear. • From 16 weeks colostrum can be expressed
- 50. c. Changes in the pelvic organs • The changes are demonstrated during V/E and may also be due to pelvic congestion Hegar’s signs • On bi-manual examination with two fingers of one hand in the anterior fornix of the vagina and the fingers of the other hand are pressing downwards on the anterior abdominal wall, the fingers of the hands almost meet because of the soft elongated isthmus which is marked between the 6th -12th week of pregnancy. Softening of the lower uterine segment.
- 52. Jacquemier’s/Chadwicks sign • From the 8th week there is a dark purplish colouration of the mucosa of the cervix, vagina and vulva due to increased blood supply to the area causing congestion of the tissues.
- 55. Osiander’s sign • From the 8th week increased pulsation is felt in the lateral fornices of the vagina due to the increase in vascularity • Goodell’s sign: significant softening of the vaginal portion of the cervix from increased vascularization. Softening of the cervix
- 56. Uterine changes • From the 8th week the uterus increases in size and becomes more globular in shape and by the 12th week the fundus can be palpated abdominally d. Abdominal changes • From the 12th week as the uterus grows and becomes an abdominal organ the height of fundus rises and the abdomen enlarges
- 57. e. The uterine soufflé • From the 16th week a soft blowing sound which synchronizes with the pregnant woman’s pulse can be heard on auscultation. • It is a sign of the maternal blood passing through the enlarged uterine vessels f. Braxton Hicks contractions • From the 20th week of pregnancy these painless contractions may be felt on abdominal palpation
- 58. Diagnostic (Conclusive) S&S of pregnancy These signs cannot be mistaken for any other condition and gives conclusive proof of pregnancy Fetal heart sounds • These can be noticed on auscultation by using a pinnard stethoscope from the 20th week after the LMP, electro-cardiotocograph from about 15weeks and is recorded accurately from 32- 34weeks after LMP, ultra sound from 6weeks.
- 59. Fetal parts • On abdominal palpation the fetal parts can be palpated from about 24th week of pregnancy and the lie and presentation can be defined in most instances. Fetal movements • On palpation the fetal movements can be felt by the 22nd week after the LMP
- 60. Visualization of the fetus • By ultra sound – the fetal sac can be outlined from the 5th week and the heart can be seen beating by the 6th week • X-ray– the fetal skeleton can be demonstrated by the 15th week of pregnancy. It is only used when there are indications of fetal death or if all the alternative methods are not available
- 61. Signs of previous pregnancy For personal reasons a woman may not admit to have previous pregnancy, the following are some of the signs; • The breast may be flabby with prominent nipples and persistence of the areolar • The abdomen- abdominal muscles may be stretched, skin loose and silvery. The fetal parts are often easier to palpate than in a primigravida
- 62. • Vulva – pigmentation may have persisted with gapping of the labia and vaginal introitus. Scarring of the perineum from an episiotomy or tearing may be present. • The vagina may be laxed and roomy • The cervix – on speculum examination the external cervical os is a transverse slit which easily admits atleast on finger. In a nulliparous the cervical os has a small round opening
- 63. The end