The anatomy and physiology of pregnancy by chikwala.pptx

Reproductive system

1. The Anatomy And Physiology Of Pregnancy Chikwala victor BScM

2. Learning objectives At the end of this session students should be able to Define of terms related to pregnancy Describe the anatomical and physiological adaptations to pregnancy

3. Definition of terms Pregnancy or gestation: the time during which one or more offsprings develop inside a women. Gravida: a woman who is pregnant Gravidity: pregnancy Multigravida: a woman who has had two or more pregnancies Multipara : a woman who has completed two or more pregnancies to 20 or more weeks of gestation Nulligravida: a woman who has never been pregnant

4. Definition of terms Nullipara: a woman who has not completed a pregnancy with a fetus or fetuses who have reached 20 weeks of gestation Parity: the number of pregnancies in which the fetus or fetuses have reached 20 weeks of gestation when they are born, not the number of fetuses (e.g., twins) born. Fetus born alive or stillborn does not affect parity postdate or postterm: a pregnancy that goes beyond 42 weeks of gestation Preterm: a pregnancy that has reached 20 weeks of gestation but ends before completion of 37 weeks of gestation

5. Definition of terms Primigravida : a woman who is pregnant for the first time Primipara: a woman who has completed one pregnancy with a fetus or fetuses who have reached 20 weeks of gestation Term: a pregnancy from the completion of 37 weeks of gestation to the end of week 42 of gestation Viability: capacity to live outside the uterus; there are no clear limits of gestational age or weight.

6. Adaptations to pregnancy During pregnancy anatomical, physiological and biochemical change occur Changes occur to the genital organs and all systems of the body Changes are due to: The hormones of pregnancy Mechanical pressure due to increasing size of uterus and fetus

7. Adaptations to Pregnancy Adaptations occur in order to; Protect the woman’s normal physiologic functioning, Meet the metabolic demands pregnancy imposes on her body, Provide a nurturing environment for fetal development and growth.

8. The Reproductive System Vulva and vagina Vulva becomes vascular and hypertrophied, pigmented and superficial varicosities may appear. Vagina becomes vascular and hypertrophied, looks bluish, fells soft. Increased blood supply of the venous plexus surrounding the walls gives the bluish colouration of the mucosa( Jacquemier’s sign) Vaginal secretion, increases in amount and is acidic (3.5-6) due to the production of lactic acid

9. The cervix Remains 2.5 cm long throughout pregnancy, There is hypertrophy and hyperplasia of the elastic and connective tissues Oestrogen increases cervical vascularity and if viewed through a speculum the cervix looks purple Marked hypertrophy and hyperplasia of the glands All these lead to marked softening of the cervix (Goodell’s sign) evident as early as 6 weeks

10. The cervix Cervical mucosa undergo hypertrophy and hyperplasia and occupies inner half of cervix. A mucus plug called “operculum” is formed between the internal and external os . The cervix is directed posteriorly but after the engagement of the head, directed in line of vagina Unfolding of the isthmus; beginning 12 weeks onwards and takes part in the formation of the lower uterine segment In pregnancy the changes in the cervix facilitate its dilatation during labor

11. Cervical Changes in Pregnancy

12. The Uterus Early uterine enlargement results from; Increased vascularity and dilation of blood vessels Hyperplasia Hypertrophy Development of the decidua By 12 weeks of gestation uterine enlargement is due to mechanical pressure of the growing fetus

13. The uterus Non-pregnant state measures about 7.5 cm in length, 5 cm in breadth and 2.5 cm in thickness. Gravid uterus gradually enlarges from 60 gm muscular organ to 900 gm at term pregnancy. Length becomes 35 cm; breadth 22.5 cm and thickness 20 cm. Uterine wall forms a sac containing amniotic fluid and foetus

14. Arrangement of the muscle fibres 1)Outer longitudinal – follows a hood like arrangement over the fundus . 2) Inner circular – It is scanty and have sphincter like arrangement around the tubal orifices and internal os 3) Intermediate – It is the thickest and strongest layer arranged in criss -cross fashion through which the blood vessels run. Apposition of two double curve muscle fibres give the figure of ‘8’ form, it called as living ligature

15. Arrangement of the muscle fibres

16. Arrangement of the muscle fibres The outer longitudinal layer of muscle fibres contract and retract during labour causing upper segment to thicken. The thickened upper segment acts as a piston to force the foetus into the receptive, passive lower segment

17. Uterine position Normal anteverted positions exaggerated up to 8 weeks The enlarged uterus may lie on the bladder Afterwards, it becomes erect, the long axis of the uterus conforms more to the axis of the inlet. Primigravidae with good tone of the abdominal muscles, it is held firmly against the maternal spine

18. Uterine Contractions Braxton-Hicks : Irregular, infrequent, spasmodic and painless without any effect on dilatation of the cervix. These contractions facilitate uterine blood flow through the intervillous spaces of the placenta Endometrium : structural and secretory activity of the endometrium

19. Isthmus During the first trimester: Isthmus hypertrophies and elongates to about 3 times its original length. It becomes soft Beyond 12 weeks, it unfolds from above, until it is incorporated into the uterine cavity. The circularly arranged muscle fibers in the region function as a sphincter in early pregnancy and thus help to retain the fetus within the uterus.

20. Elongation and formation of the lower uterine segment

21. Ovaries Ovulation ceases throughout pregnancy. Corpus luteum of usual menstrual cycle persists and enlarges to 2.5 cm till 8 th week due to the changes in the fertilized ovum (trophoblast) and Helps in producing hormones. Oestrogen and progesterone secreted by the corpus luteum maintain the environment for the growing ovum Control the formation and maintenance of decidua of pregnancy Inhibit ripening of the follicles At 6-7 wks the placenta begins manufacturing progesterone, & involution of the corpus luteum begins.

22. Breasts Under the stimulation of estrogen and progesterone the breasts increase in size, nodularity and sensitivity throughout pregnancy with increased vascularity. Total weight becomes 0.4 kg volume. Enlargement is due to alveolar proliferation and deposition of fat. Sebaceous glands (5-15) become hypertrophied and are called Montgomery’s tubercles

23. Breasts Areola becomes dark pigmented, which is primary areola, A second zone of pigmentation appears around the primary areola in second trimester, which is secondary areola. Secretion (colostrum) can be squeezed out of the breast at about 12th week

24. CUTANEOUS CHANGES Face (chloasma gravidarum or pregnancy mask) an extreme form of pigmentation around the cheek, forehead and around the eyes

25. ABDOMEN Linea nigra : a brownish black pigmented area in the midline stretching from the xiphisternum to the symphysis pubis Straie graviderum :slightly depressed linear marks with varying length and breadth found in pregnancy

26. CHANGES IN OTHER SYSTEMS OF THE BODY Cardiovascular System Heart works more during pregnancy. Increase in the cardiac volume by 10% No change in E.C.G. Cardiac output increases by 15-30% due to increased heart rate and increase stroke volume. Pulse rate near term increases by 10 per minute. Platelet count shows slight decrease due to increased concentration

27. Blood Pressure and Blood volume Blood pressure remains within normal limits Due to pressure of gravid uterus on pelvic veins Venous pressure– Femoral venous pressure rises. Blood volume increases from 3rd month and reaches a peak of 25% rise at 32 weeks. The red cell volume increases by 200 ml, Plasma volume increases to 1000 ml

28. Respiratory System Increased inspiration so the increased oxygen intake results in improved oxygen supply to the foetus. Increased expiration, more carbondioxide is expelled, There is low maternal carbondioxide leading to easy transfer of CO2 from foetus to mother’s blood. Breathing difficulty which is relieved after lightening.

29. Digestive system Regurgitation of stomach juice and heart burn Slow emptying of stomach Constipation. Gums become spongy and vascular and may bleed during brushing in many women.

30. Nervous System Slumpliness is common and mood changes occur in many. Pregnancy is one of the periods in a woman’s life when there seems to be lowering of the ability to cope with emotional experiences in life. Even the cases where the coming of the baby is welcome a mild degree of depression or irritability may be evident during the early months.

31. Urinary System Frequency of micturition Stress incontinence Due to dilatation of uterus and renal pelvis during early pregnancy which continues till mid-pregnancy there is a tendency for urinary stasis and these favours infection. Glomerular filtration rate (GFR ) increases by 50% early in pregnancy, increasing creatinine clearance. Serum creatinine and urea will fall by about 25%.

32. Urinary System Increased GFR also increases filtered sodium. Aldosterone levels rise by 2-3 times to reabsorb the filtered sodium. Increased GFR and impaired tubular reabsorption of glucose produce glucosuria in approximately 15% of normal pregnancies. Proteinuria is abnormal in pregnancy

33. Musculoskeletal System The body's posture changes as the pregnancy progresses. The pelvis tilts and the back arches to help keep balance. Poor posture occurs naturally from the stretching of the woman's abdominal muscles as the fetus grows. These muscles are less able to contract and keep the lower back in proper alignment.

34. Musculoskeletal System The pregnant woman has a different pattern of gait. The step lengthens as the pregnancy progresses, due to weight gain and changes in posture. The influences of increased hormones such as estrogen and relaxin initiate the remodeling of soft tissues, cartilage and ligaments. Increased ligamental laxity caused by increased levels of relaxin contribute to back pain and pubic symphysis dysfunction. Shift in posture with exaggerated lumbar lordosis leading to the typical gait of late pregnancy.

35. Hematology During pregnancy the plasma volume increases by 50% and the red blood cell volume increases only by 20-30%. Consequently, the hematocrit decreases on lab value; this is not a true decrease in hematocrit, however, but rather due to the dilution.

36. Hematology A pregnant woman will also become hypercoagulable , leading to increased risk for developing blood clots and embolisms, due to increased liver production of coagulation factors, mainly fibrinogen and factor VIII Hypercoagulable state along with the decreased ambulation causes an increased risk of both DVT and PE

37. . Edema , or swelling, of the feet is common during pregnancy, partly because the enlarging uterus compresses veins and lymphatic drainage from the legs.

38. Maternal Weight Gain In normal pregnancy the average gain is 0.3 Kg/week up to 18 weeks, 0.45 Kg/week from 18-28 weeks and a slight reduction with a rate of 0.36-0.41 Kg/week until term. Failure to gain weight and sometimes slight weight loss may occur in the last 2 weeks. The average weight gain for primigravidae for is 12.5 Kg. and is probably about 0.9 Kg. less for multigravidae.

39. Weight gain is produced by: Fetus 3.63-3.88 Kg Placenta 0.48-0.72 Kg Amniotic fluid 0.72-0.97 Kg Uterus and breasts 2.42-2.66 Kg Blood and fluid 1.94-3.99 Kg Muscle and fat 0.48-2.91 kg Total= 9.70-14.55Kg

40. Endocrine System Thyroid activity is increased – In normal pregnancy thyroid gland increases in size by about 13 % due to hyperplasia and increased vascularity. There is normaly an increased uptake of iodine during pregnancy , which may be due to compensate for renal clearance of iodine leading to a reduced level of plasma iodine

41. Role of Estrogen in Pregnancy: Increasing blood flow to the uterus by promoting vasodilation. Changing the sensitivity of the respiratory system to carbon dioxide. Softening of the cervix, initiating uterine activity, and maintaining labor. Developing the breasts in preparation for lactation and secretion of prolactin by the pituitary gland.

42. Role of Progesterone in Pregnancy: Ready the uterus for implantation. Relaxes smooth muscle to prevent spontaneous abortion. Works to prevent a maternal immunologic response to the fetus. Relaxes smooth muscle to decrease motility & improve absorption of nutrients. Enlarges the ureters & bladder to increase capacity. Plays a role in development of the alveoli & ductal system to prepare for lactation.