What are common causes of increased alpha-fetoprotein concentrations in maternal serum?

Increased levels of alpha-fetoprotein (AFP) in maternal serum are commonly associated with several factors, primarily linked to gestational conditions. One significant cause is inaccurate dating of the gestational age, as miscalculated gestational weeks can lead to assessments that misinterpret the normal range of AFP. AFP levels peak at different times in pregnancy, so a gestational dating error can artificially inflate or deflate perceived AFP levels.

Multiple gestations, such as twins or triplets, also cause elevated AFP concentrations. In these cases, the presence of more than one fetus leads to a higher production of AFP as each fetus contributes to the overall maternal serum levels.

The other options provided do not typically correlate with increased AFP levels. For instance, while obesity and hypertension can impact pregnancy, they are not direct causes of elevated AFP. Similarly, excessive exercise and smoking do not have established links to increased AFP levels during pregnancy. Low protein diets and maternal age might influence other aspects of maternal and fetal health but are not common causes of elevated AFP.

Thus, inaccuracies in gestational dating and the presence of multiple fetuses are key contributors to increased AFP concentrations in maternal serum.