28 Obstetrics and Gynecology Board Review •••
❍ What percentage of maternal weight gain is contributed by blood, amniotic fluid, and extravascular fluid
at term?
Approximately 30%.
❍ What percentage of maternal weight gain is contributed by maternal fat?
30%.
❍ At term, what is the water content in liters of the fetus, placenta, and amniotic fluid?
3.5 L.
❍ What is the total amount of extra water that a pregnant woman retains during normal pregnancy?
6.5 L total—3.5 L for the fetus, placenta, and amniotic fluid and 3.0 L for the increased volume of blood, uterus,
and breasts.
❍ Why does water retention, a normal physiologic alteration of pregnancy, and edema occur in normal pregnancy?
Fall in plasma osmolality of 10 mOsm/kg. Prepregnancy plasma osmolality is about 290 mOsm/kg. At 4 weeks, it
starts to drop and by 8 weeks it plateaus to about 280 mOsm/kg.
❍ Describe the utility of increased body protein during pregnancy.
One half of the normal increase in body protein during pregnancy, 500 g, is contained in the fetus and placenta.
The other 500 g of protein is incorporated in contractile proteins in the uterus, glands of the breast, maternal
blood proteins, and hemoglobin.
❍ In a healthy pregnant woman what happens to the fasting plasma glucose level and why?
It is decreased by 8 to 10 mg/dL in the first trimester with little change after that. This negates fetal demand as the
cause; therefore, it is probably a dilutional effect.
❍ In a healthy pregnant woman how long does it take to return to fasting glucose levels after a glucose load?
The levels peak later (55 min when pregnant vs. 30 min when not) and remain elevated longer, thereby prolonging
the return to fasting level to about 2 hours (usually 1 hour in nonpregnant patients).
❍ What is the state of carbohydrate metabolism in normal pregnancy in terms of fasting glucose, postprandial
glucose, insulin levels and insulin resistance?
Mild fasting hypoglycemia, postprandial hyperglycemia, hyperinsulinemia, and increased insulin resistance.
❍ What are the changes in the pancreas seen in normal pregnancy?
Beta cell hypertrophy, hyperplasia, and hypersecretion.
❍ In a normal pregnancy, what effect does a glucose stimulus have on glucagon levels?
Plasma glucagon levels are suppressed.
❍ What is the general trend of serum lipid concentrations in pregnancy?
Increase continuously throughout gestation. This includes triglycerides, cholesterol, phospholipids, and fatty acids.