Hypertension is reported to complicate one out of ten pregnancies, which makes it the most common medical disorder in pregnancy. It is important to have a correct diagnosis of hypertension during pregnancy, with the emphasis on differentiating pre-existing hypertension from pregnancy induced hypertension (gestational and the syndrome of pre-eclampsia). During pregnancy, the challenge is to determine when to use antihypertensive medications and which level of blood pressure to target. A balance has to be found between the potential risk to the health of the baby related to drug-exposure and the risk to the mother and baby due to an untreated medical condition (severe hypertension).
Antihypertensive drug use during pregnancy is relatively common and increasing. Only a small proportion of available antihypertensive drugs have been tested in pregnant women, and many are contraindicated. It is important to make the exposure of medications to the baby as small as possible. It is not clear if treating women who have mild or moderate hypertension during pregnancy with anti-hypertensive medication is beneficial.
The most common first trimester antihypertensive are β-blockers. The consequences of treatment with β-blocker during pregnancy are disputable. Some studies report a connection between β-blocker treatment and small for-gestational-age (SGA) of newborns and pre-term birth, while others do not. Based on meta-analyses, first trimester oral β-blocker use showed no increase in odds of major congenital anomalies. However, analyses examining organ-specific malformations observed increased odds of cardiovascular defects, cleft lip and neural tube defects. The U.S. Food and Drug Administration (FDA) categorises β-blockers into different pregnancy categories depending on the safety of the drugs and they range from category B to D, that is, no β-blockers is completely safe for using during pregnancy