Women who are pregnant or who may become pregnant should discuss the use of vasodilators with their physician before taking the medication. While some medication can be used during preganancy to treat pregnancy-induced hypertension, in most cases, women who are pregnant should avoid the use of vasodilators. This is especially true of ACE inhibitors, which can cause birth defects or death in the fetus if taken at any time during pregnancy. Women who become pregnant while taking ACE inhibitors should consult their physician immediately to discuss other methods of controlling high blood pressure.

ACE inhibitors and other types of vasodilators may also cause jaundice, blood problems and signs of low potassium levels in newborns.

Women who are breast feeding may be advised to avoid taking vasodilators, especially in the first month of nursing. Some types of vasodilators pass into breast milk and may be harmful for nursing children. Thiazide diuretics, in particular, may result in decreased flow of breast milk if taken during the first month of nursing.