Which risk factor can lead to increased congenital abnormalities during pregnancy?

Maternal obesity is a significant risk factor that can lead to an increased likelihood of congenital abnormalities during pregnancy. Research shows that women with obesity face a higher risk for various complications, both maternal and fetal. Specifically, maternal obesity is associated with a higher prevalence of neural tube defects, congenital heart defects, and other abnormalities. This elevated risk is thought to be due to a combination of factors, including metabolic and hormonal changes that obesity can induce, as well as potential genetic and environmental interactions.

In contrast, while gestational diabetes can pose risks for the developing fetus and complicate the pregnancy, particularly regarding macrosomia and metabolic syndrome in the child, it is not directly linked to an increased risk of congenital abnormalities in the same way that maternal obesity is. Advanced paternal age, while also associated with certain risks, is generally more linked to conditions like autism spectrum disorders and schizophrenia rather than congenital malformations in the traditional sense. Excessive exercise during pregnancy typically does not have the same adverse effect on fetal development and can be beneficial for maternal health if done appropriately.

Thus, maternal obesity is the clear risk factor that has been extensively studied and shown to correlate with an increased risk of congenital abnormalities during pregnancy.