Maternal Changes During Pregnancy
STRUCTURAL CHANGES :
I Genital Organs :
(1) Vulva : \ Oedematous and hyperaemic
(2) Vagina : \ Hypertrophy and Hyperaemia
\ pH - 3.5-6
(3) Uterus : \ Weight - 900-1000 gm
\ Length - 35cm
(4) Body of the uterus : \ Hypertrophy and Hyperplasia of the muscles. Formation of new muscle fibres. Stretching of the muscle fibres.
\ Vascular supply - Ovarian Artery
\ Braxton - Hicks Contractions +
(5) Isthmus : \ Sphincteric function.
(6) Cervix : \ Hypertrophy and Hyperplasia.
\ Vascularity
\ Endocervical mucosa proliferation
(7) Fallopian tubes : \ Congestion
(8) Ovary : \ Corpus luteum persists upto 8th week with 2.5 cm size.
II Other Organs :
(1) Breasts : \ Hypertrophy and proliferation of ducts and alveoli.
\ Montgomery's tubercles +
\ Secretion starts from 12 weeks gestation age.
(2) Skin : \ Chloasma
\ Striae gravidarum
\ Linea nigra
FUNCTIONAL CHANGES :
1. Weight gain and water metabolism :
Total weight gain during the course of a singleton pregnancy averages 11 Kg. This has been distributed to 1 Kg in first trimester and 5 Kg each in second and third trimesters.
The water is the chief component of the net weight gain (At term 6.5 lit.). During pregnancy, there is variable amount of retention of electrolytes like Sodium (20 gm), potassium (10 gm) and chlorides occur.
2. Haematogical and Haemodynamic changes :
The blood volume and plasma volume increases parallel during gestation period. Total plasma volume increases to the extent of 1.3 litres.
3. Metabolic changes :
Total metabolism is increased due to the needs of the growing uterus and the foetus.
(1) Protein metabolism : There is a positive nitrogen balance throughout pregnancy. At term, the foetal placenta contain about 500gm of protein and the maternal gain is about 500 gm. The blood urea level falls to 15-20 mg%.
(2) Carbohydrate metabolism : Carbohydrate metabolism increases in pregnancy. Fasting blood sugar remains slightly at a lower level than in the non-pregnant state due to foetal consumption.
(3) Fat metabolism : There is increased absorption of fat in lateral months of pregnancy.
(4) Iron metabolism : Total additional iron requirement during pregnancy is estimated approximately 725 mg. In the second half of pregnancy, the daily requirement actually becomes very much increased to the extent of about 6mg.
4. Systemic changes :
1. Respiratory system :
CHANGES IN RESPIRATORY SYSTEM
| Sr.No. | | Non Pregnant | Pregnancy near term | Change |
| (1) | Respiration rate / min | 15 | 15 | Unaffected |
| (2) | Vital capacity (ml) | 3200 | 3300 | Almost unaltered |
| (3) | Tidal Volume (ml) | 475 | 675 | +40% |
| (4) | Residual volume (ml) | 965 | 765 | -20% |
| (5) | Arterial Pco2 | 38 mm Hg | 32 mm Hg | ¯ |
| (6) | pH | 7.40 | 7.44 | Slight |
| (7) | Arterial Po2 | 95 mm Hg | 105 mm Hg | |
2. Urinary System :
(a) Kidney : Renal plasma flow is increased by 25-50% maximum in the first trimester. Glomerular filtration rate is increased by 50% all throughout pregnancy.
(b) Ureter : There is elongation, kinking and outward displacement of the ureters.
(c) Bladder : Marked congestion with hypertrophy of the muscles and elastic tissues of the wall.
3. Alimentary System : Muscle tone and motility of the entire gastrointestinal tract are diminished due to high progesterone level.
Liver and Gallbladder : Liver functions are depressed. There is marked atonicity of gall bladder.
4. Nervous System : Some sort of temperamental changes are found during pregnancy.
5. Calcium metabolism and locomotor system : Total calcium requirement in pregnancy is 28gm, 2/3rd of which is required in last trimester. Daily requirement of calcium during pregnancy averages 1-1.5 gm.
There is increased mobility of the pelvic joints due to softening of the ligaments.
6. Endocrine system : There is profound change in endocrine system. From 8 weeks onwards, placenta produces a variety of harmons of which steroids and protein hormones are significantly important :
(a) Protein hormones : (1) HCG, HPL, HCT, HCC, PSbG
(b) Steroid hormones : (1) oestrogens - oestriol, oestradiol and oestrone
(2) Progesterone.
Besides these hormones, placenta also produces releasing hormones, enzymes and protein. These are (1) TRH (2) LH/FSH-RH.
