Which electrolyte trend is observed by mid-pregnancy?

Which electrolyte trend is observed by mid-pregnancy?

• A. Sodium decreases 2 to 4 mEq/L
• B. Sodium increases 2 to 4 mEq/L
• C. Sodium remains unchanged
• D. Sodium increases 10 mEq/L

Answer: (A)

During mid-pregnancy the blood plasma volume expands greatly to support the growing fetus. This surge in total body water dilutes plasma electrolytes, so sodium often falls slightly—a mild dilutional hyponatremia. The typical shift is about 2 to 4 mEq/L lower than pre-pregnancy levels, which is considered a normal physiologic change in pregnancy. This trend wouldn’t be expected to show an unchanged sodium level or a substantial increase (such as +10 mEq/L).

During mid-pregnancy the blood plasma volume expands greatly to support the growing fetus. This surge in total body water dilutes plasma electrolytes, so sodium often falls slightly—a mild dilutional hyponatremia. The typical shift is about 2 to 4 mEq/L lower than pre-pregnancy levels, which is considered a normal physiologic change in pregnancy. This trend wouldn’t be expected to show an unchanged sodium level or a substantial increase (such as +10 mEq/L).