Physiological changes in pregnancy: renal function, alimentary system, nutrients in blood, skin, breasts. Maternal weight gain, endocrine changes.

Question 1

Changes in what areas

Answer 1

Renal
Alimentary
Nutrients
Maternal weight gain
Breasts
Skin
Endocrine changes

Question 2

Renal function

Answer 2

1. By the third trimester calyces, pelvis and ureters dilate and Renal parenchyma increases by 70%.

The effects are slightly more pronounced in the right kidney due to anatomical contribution.

2. GFR increases and renal blood flow GFR increases by 50-80% and falls down towards term.
3. Water retention and plasma volume increase with a peak in week 32-34. Total increase is 50% in first pregnancy and 60% in second or later pregnancies and is associated with apparent decrease

in Na+ and other ions due to dilution although these ions and other metabolites such as glucose
actually increase (the water retention is more pronounced)

4. Poor fetal growth is associated with impaired increase in plasma volume.
5. Glucose excretion increase and glycosuria is common is normal pregnancy.
6. Protein excretion is slightly elevated (≤0.2mg/L in 24-hour collection is acceptable in pregnancy)

Question 3

Alimentary system

Answer 3

1. Reduced gastric secretion, motility, gastric emptying due to water retention.
2. Heartburn is common due to displacement of the lower esophageal sphincter (LES)
3. Liver synthesis more albumin, globulins and fibrinogen under estrogen stimulation.
4. Gallbladder increases in size and is more slowly in emptying.

Question 4

Nutrients

Answer 4

1. No change in glucose or insulin metabolism, however, there is a fall in blood glucose to 1mmol/L
   lower than non-pregnant and rise in insulin concentrations
2. Pregnant women develop insulin resistance due to human placental lactogen or cortisol.
3. Fall in amino acids due to increased plasma insulin and placental uptake.
4. Elevated lipid concentration, especially VLDL, TAGs and cholesterol (~50%).
5. Hyperlipidemia in pregnancy is not atherogenic (can unmask true hyperlipidemia).
6. Fat soluble vitamins rise and water-soluble vitamins tend to fall

Question 5

Maternal weight gain

Answer 5

1. Pregnancy is anabolic state, average weight gain is total of 12.5kg – mostly due to water
   retention.
2. 0.3kg/week up to week 18 and 0.5kg/week from week 18-28 and afterwards 0.4kg/week until
   term.
3. BMR rises by %5.
4. Joint, ligaments laxity is due to water retention.
5. High weight gain is associated with edema and pre-eclampsia.
6. Immediate ~6kg loss after delivery (water and uterine products).
7. By 10 weeks post-delivery weight gain is about ~2.5kg above pre-pregnant weight and by 6-18
   month it is 1-2kg above pre-pregnant weight.

Question 6

Breasts

Answer 6

1. First signs of pregnancy include increase in breast tenderness, size, nipples, vascularity and
   pigmentation.
2. Ductal proliferation is stimulated by estrogen whereas glandular growth is by progesterone andprolactin.
3. Colostrum is the “first milk” thick, protein rich expressed in the breasts in the period of 30 hours
   post-delivery.
4. Progesterone and estrogen fall and fetal suckling and crying stimulate prolactin to stimulates
   production of milk (casein, fatty acids, albumin). 500mL-100-mL of daily milk production can be
   achieved.
5. Suckling also promotes oxytocin which stimulates milk ejection.

Question 7

Skin

Answer 7

1. Elevated MSH is typical (chloasma pigmentation on the face, linea nigra in the abdomen and
   areolar pigmentation).
2. Striae gravidarum abdominal stretch marks due to collagen disruption and uterus distension.
3. Skin blood flow increases and more heat loss occurs

Question 8

Endocrine changes

Answer 8

1. Androgenic hormones dominate.
2. Placental hormones: increase in hCG, estrogen, progesterone for uterine, breast, vascular and
   placental growth. CRH increased in third trimester for labor.
3. Pituitary gland: increase in lactotrophs, ACTH and MSH. Decrease in gonadotropin due to hCG.
4. Posterior pituitary: increase in vasopressin and oxytocin.
5. Hypothalamus: CRH increased in third trimester for labor.
6. Iodine levels fall due to thyroid enlargement, fetal uptake of iodothyronines and iodine
   excretion → increased thyroid function.
7. Fall in PTH but doubling in vitamin D (placenta also forms this hormone called PTHrP).
8. All components of RAAS system increase.