Serum calcium during pregnancy tends to:

Serum calcium during pregnancy tends to:

• A. Increase due to albumin rise
• B. Decrease related to decreases in albumin; lowest between 28 and 32 weeks, then plateaus
• C. Remain constant
• D. Fluctuate unpredictably

Answer: (B)

During pregnancy, changes in albumin and blood volume drive serum calcium trends. Calcium in the blood is largely bound to albumin, so when plasma volume expands and albumin concentration falls (hemodilution), total serum calcium decreases even though the active ionized calcium remains normal. This causes a gradual decline that reaches a low point in the late second trimester, around 28–32 weeks, and then levels off as the mother's physiology adapts. So the best description is a decrease related to decreases in albumin, with the lowest levels around 28–32 weeks followed by a plateau. If albumin is low, total calcium may appear low, but ionized calcium stays stable, which is why interpreting calcium during pregnancy should consider albumin levels.

During pregnancy, changes in albumin and blood volume drive serum calcium trends. Calcium in the blood is largely bound to albumin, so when plasma volume expands and albumin concentration falls (hemodilution), total serum calcium decreases even though the active ionized calcium remains normal. This causes a gradual decline that reaches a low point in the late second trimester, around 28–32 weeks, and then levels off as the mother's physiology adapts. So the best description is a decrease related to decreases in albumin, with the lowest levels around 28–32 weeks followed by a plateau. If albumin is low, total calcium may appear low, but ionized calcium stays stable, which is why interpreting calcium during pregnancy should consider albumin levels.