Which lipid-lowering agent is generally contraindicated in pregnancy?

Statins are generally contraindicated in pregnancy due to their mechanism of action and the potential risks they pose to fetal development. Statins work by inhibiting the enzyme HMG-CoA reductase, which plays a critical role in the synthesis of cholesterol. Cholesterol is essential for many biological processes, including fetal development. Studies suggest that statin use during pregnancy could lead to adverse outcomes, such as birth defects or developmental issues, particularly because cholesterol is vital for the development of the fetal nervous system.

In contrast, the other lipid-lowering agents listed have a different safety profile. Fibrates have limited data regarding their effects in pregnancy, but they are generally not used due to a lack of sufficient evidence regarding their safety. Bile acid sequestrants are considered relatively safe in pregnancy because they do not significantly affect systemic cholesterol levels and act locally in the gastrointestinal tract. Niacin also lacks sufficient evidence to be flagged as particularly harmful in pregnancy, although its use is usually approached with caution.

Given these considerations, the use of statins during pregnancy is strongly advised against, making them the correct choice for this question.