PHYSIOLOGICAL CHANGES IN PREGNANCY

DR. ZEINAB ABOTALIB

ASSO. PROF. & CONSULTANT

PHYSIOLOGICAL CHANGES IN PHYSIOLOGICAL CHANGES IN PREGNANCYPREGNANCY

Volume HomeostasisVolume Homeostasis 1.The factors contributing to fluid retention are:1.The factors contributing to fluid retention are: Sodium retentionSodium retention Resetting of osmostatResetting of osmostat Decrease in thirst thresholdDecrease in thirst threshold Decrease in plasma oncotic pressureDecrease in plasma oncotic pressure

2. Consequences of fluid retention are2. Consequences of fluid retention are Haemoglobin concentration fallsHaemoglobin concentration falls Haematocrit fallsHaematocrit falls Serum albumin concentration fallsSerum albumin concentration falls Stroke volume increasesStroke volume increases Renal blood flow increasesRenal blood flow increases

Haematological ChangesHaematological Changes Decreases in:Decreases in: Red cell countRed cell count Haemoglobin concentrationHaemoglobin concentration HaematocritHaematocrit Plasma folate concentrationPlasma folate concentration Increases in:Increases in: white cell countwhite cell count erythrocyte sedimentation rateerythrocyte sedimentation rate fibrinogenfibrinogen

Cardiovascular SystemCardiovascular System Normal changes in heart sounds during Normal changes in heart sounds during

pregnancy:pregnancy: Increased loudness of both s1 and s2Increased loudness of both s1 and s2 Increased splitting of mitral and tricuspid components Increased splitting of mitral and tricuspid components

of s1of s1 No constant changes in s2No constant changes in s2 Loud s3 by 20 weeks’ gestationLoud s3 by 20 weeks’ gestation <5% with s4<5% with s4 >95% develop systolic murmur which disappears >95% develop systolic murmur which disappears

after deliveryafter delivery 20% have a transient diastolic murmur20% have a transient diastolic murmur 10% develop continuous murmurs due to increased 10% develop continuous murmurs due to increased

mammary blood flow mammary blood flow

Cardiovascular ChangesCardiovascular Changes Heart rate increases (10-20%)Heart rate increases (10-20%) Stroke volume increases (10%)Stroke volume increases (10%) Cardiac output increases (30-50%)Cardiac output increases (30-50%) Mean arterial pressure decreases (10%)Mean arterial pressure decreases (10%) Peripheral resistance decreases (35%)Peripheral resistance decreases (35%)

REPRODUCTIVE ORGANSREPRODUCTIVE ORGANS

The UterusThe Uterus

The CervixThe Cervix

BREASTS AND LACTATIONBREASTS AND LACTATION

ENDOCRINE GLANDSENDOCRINE GLANDS1.1. Pituitary glandPituitary gland

-- FSH and LH FSH and LH ↓↓-- ACTH, Thyrotrophin, melanocyte hormone and ACTH, Thyrotrophin, melanocyte hormone and prolactin prolactin ↑↑- Prolactin level - Prolactin level ↑↑ until the 30 until the 30thth week of week of

pregnancy then more slowly to term.pregnancy then more slowly to term.Enlarges during pregnancyEnlarges during pregnancy

7.7. Adrenal glandAdrenal glandTotal corticosteroids Total corticosteroids ↑↑ progressively to term. This will progressively to term. This will ↑↑ the tendency of pregnant women to develop abdominal the tendency of pregnant women to develop abdominal striae, glycosuria and hypertensionstriae, glycosuria and hypertension

1.1. Thyroid glandThyroid gland-- Enlarges during pregnancy, occasionally to Enlarges during pregnancy, occasionally to twice its normal size. This is mainly due to twice its normal size. This is mainly due to colloid deposition caused by a lower plasma colloid deposition caused by a lower plasma level of iodine, consequent to the increased level of iodine, consequent to the increased ability of the kidneys to excrete during ability of the kidneys to excrete during pregnancy.pregnancy.-- Oestrogen stimulates or increased secretion Oestrogen stimulates or increased secretion of thyroxin binding globulin.of thyroxin binding globulin.-- Both T3 and T4 levels rise. This rise will Both T3 and T4 levels rise. This rise will not indicate hyperthyroidism, since TSH and not indicate hyperthyroidism, since TSH and free thyroxin are normal.free thyroxin are normal.

GENETAL TRACT CHANGESGENETAL TRACT CHANGES1.1. UTERUSUTERUS

A. Uterine muscles grow to 15 times A. Uterine muscles grow to 15 times than pre-pregnancy length. than pre-pregnancy length.- Uterine weight increases from 50 g - Uterine weight increases from 50 g before pregnancy to 950 g at term. before pregnancy to 950 g at term.- In the early weeks of pregnancy the - In the early weeks of pregnancy the growth is by hyperplasia and more growth is by hyperplasia and more particularly by hypertrophy of the particularly by hypertrophy of the muscle fibers. muscle fibers.

GENETAL TRACT CHANGES GENETAL TRACT CHANGES (con’t.)(con’t.)

- By 20 weeks growth ceases and the uterus By 20 weeks growth ceases and the uterus expands by distension.expands by distension.

- The uterine blood vessels also undergo The uterine blood vessels also undergo hypertrophy and become increasingly coiled hypertrophy and become increasingly coiled in the first half of pregnancy but no further in the first half of pregnancy but no further growth after that.growth after that.

- The lower uterine segment is that part of the The lower uterine segment is that part of the lower uterus and upper cervix lying between lower uterus and upper cervix lying between the line of attachment of the peritonum of the the line of attachment of the peritonum of the utero vesical pouch superiorly and the utero vesical pouch superiorly and the histological internal os interiorly.histological internal os interiorly.

B. THE CERVIXB. THE CERVIXBecomes softer and swollen in pregnancy, with the result that Becomes softer and swollen in pregnancy, with the result that columnar epithelium lining the cervical canal becomes columnar epithelium lining the cervical canal becomes exposed to the vaginal secretions.exposed to the vaginal secretions.

Prostaglandins act on the collagen fibres, especially in the last Prostaglandins act on the collagen fibres, especially in the last week of pregnancy. At the same time collagenae is released week of pregnancy. At the same time collagenae is released from leucocytes, which also helps in breaking down collagen. from leucocytes, which also helps in breaking down collagen. The cervix becomes softer and more easily dilatable the so The cervix becomes softer and more easily dilatable the so called ripening of the cervix.called ripening of the cervix.

C. VAGINAC. VAGINAThe vaginal mucosa becomes thick , the vaginal muscle The vaginal mucosa becomes thick , the vaginal muscle hypertrophies.hypertrophies.

There is alteratione in the compision of the connective tissue, There is alteratione in the compision of the connective tissue, with the result that the vagina dilates more easily to with the result that the vagina dilates more easily to accommodate the fetus during parturtion.accommodate the fetus during parturtion.

Oestrogen Oestrogen →→ desquamanation of the superficial vaginal desquamanation of the superficial vaginal mucosal cells with mucosal cells with ↑↑ in vaginal discharge . when pathologies in vaginal discharge . when pathologies entre the vagina (candida, trichomas) they will flourish rapidly.entre the vagina (candida, trichomas) they will flourish rapidly.

Alimentary System ChangesAlimentary System Changes::

The mouth and the gum because spongy The mouth and the gum because spongy become of intracellular flood retention become of intracellular flood retention (prophylactic effect).(prophylactic effect).

The lower oesophageal sphincter is relaxed The lower oesophageal sphincter is relaxed which may permit regurgitation of gastric which may permit regurgitation of gastric contents and cause heart burn.contents and cause heart burn.

Gastric secretion is reduced and food remains Gastric secretion is reduced and food remains larger in the stomach.larger in the stomach.

The intestinal musculature is relaxed with The intestinal musculature is relaxed with lower motility lower motility →→ greater absorption and greater absorption and constipation.constipation.

RENAL SYSTEMRENAL SYSTEM

The smooth muscle of the renal pelvis and The smooth muscle of the renal pelvis and ureters relaxes, causing their dilatation. This ureters relaxes, causing their dilatation. This increase the capacity of the renal pelvis and increase the capacity of the renal pelvis and ureters from 12 ml to 75 ml and ureters from 12 ml to 75 ml and ↑↑ the the chances of urinary stasischances of urinary stasis

Urinary tract infection is more common in Urinary tract infection is more common in pregnancy. The muscles of the internal pregnancy. The muscles of the internal urethral sphincter relax and this together urethral sphincter relax and this together with the pressure of the uterus with the pressure of the uterus →→degree of degree of incontinenceincontinence

THE URINARY TRACT AND RENAL THE URINARY TRACT AND RENAL FUNCTIONFUNCTION

Renal changesRenal changes Blood flow increases (60-75%)Blood flow increases (60-75%) Glomerular filtration increases (50%)Glomerular filtration increases (50%) Clearance of most substances is enhancedClearance of most substances is enhanced Plasma creatinine, urea and urate are reducedPlasma creatinine, urea and urate are reduced Glycosuria is normalGlycosuria is normal

- The renal blood flow increases to the 16The renal blood flow increases to the 16thth week of pregnancy and the levels off.week of pregnancy and the levels off.

- GFT increases by 60% in early pregnancy GFT increases by 60% in early pregnancy and remains at the new level until the last and remains at the new level until the last 4 weeks of pregnancy when it falls.4 weeks of pregnancy when it falls.

- Tubular reabsortion is unaltered.Tubular reabsortion is unaltered.- Clearance of many solutes Clearance of many solutes ↑↑- Up to 300 mg of protein may be excreted Up to 300 mg of protein may be excreted

in 24 hours.in 24 hours.− ↑↑ GFT + progestogen effect GFT + progestogen effect →→increase increase

loos of Na.loos of Na.

IMMUNE STSTEM CHANGESIMMUNE STSTEM CHANGES

- HCG HCG →↓→↓ immune response to pregnancy immune response to pregnancy- IgG, IgA and IgM IgG, IgA and IgM ↓↓ from 10 from 10thth week of week of

pregnancy reaching their lowest level at pregnancy reaching their lowest level at 30 weeks and remain so till the end of 30 weeks and remain so till the end of pregnancy pregnancy →↑→↑ risk of infection in pregnant risk of infection in pregnant women.women.

WEIGHT GAIN IN PREGNANCYWEIGHT GAIN IN PREGNANCY Healthy women will gain around 12 kg of Healthy women will gain around 12 kg of

which 9 kg is gained in the last 20 weeks.which 9 kg is gained in the last 20 weeks.

The elements of weight gain:The elements of weight gain:-- FetusFetus 3300 gm3300 gm-- PlacentaPlacenta 600 gm 600 gm-- UterusUterus 900 gm 900 gm-- BreastsBreasts 400 gm 400 gm-- BloodBlood 1200 1200 -- Fat DepositedFat Deposited 2500 2500-- FluidFluid 2600 2600