Which statement about diabetes in pregnancy is false?

Which statement about diabetes in pregnancy is false?

• A. Gestational diabetes mellitus occurs in 2% to 5% of pregnancies
• B. Insulin requirements increase during pregnancy
• C. Preeclampsia is more common in diabetics
• D. Insulin readily crosses the placenta and causes larger babies

Answer: (D)

In diabetes during pregnancy, the placenta creates a state of insulin resistance, so the mother often needs more insulin to control blood glucose as pregnancy progresses. A key physiological fact is that maternal insulin does not cross the placenta. Glucose does cross to the fetus, causing fetal hyperglycemia, which then stimulates the fetal pancreas to produce more insulin. That fetal insulin acts as a growth factor, contributing to a larger baby (macrosomia). So the statement that insulin readily crosses the placenta and causes larger babies is incorrect; the growth effect comes from fetal insulin in response to maternal glucose, not from maternal insulin crossing into fetal circulation. The other points—gestational diabetes prevalence around a few percent, increased insulin requirements during pregnancy due to placental hormones, and higher risk of preeclampsia in diabetics—are accurate.

In diabetes during pregnancy, the placenta creates a state of insulin resistance, so the mother often needs more insulin to control blood glucose as pregnancy progresses. A key physiological fact is that maternal insulin does not cross the placenta. Glucose does cross to the fetus, causing fetal hyperglycemia, which then stimulates the fetal pancreas to produce more insulin. That fetal insulin acts as a growth factor, contributing to a larger baby (macrosomia). So the statement that insulin readily crosses the placenta and causes larger babies is incorrect; the growth effect comes from fetal insulin in response to maternal glucose, not from maternal insulin crossing into fetal circulation. The other points—gestational diabetes prevalence around a few percent, increased insulin requirements during pregnancy due to placental hormones, and higher risk of preeclampsia in diabetics—are accurate.