High blood pressure in the first trimester responsible for birth defects rather than medication

High blood pressure in the early stages of pregnancy causes birth defects rather than the drugs used to treat it, new research finds.

Dr De-Kun Li of the Kaiser Foundation Research Institute in California and published on the British Medical Journal website says “Our finding suggests that it is likely the underlying hypertension rather than use of antihypertensive drugs in the first trimester that increases the risk of birth defects in offspring.”

Whilst Angiotensin-converting enzyme (ACE) inhibitors are are commonly used to treat hypertension and have a known toxic effect in the second or third trimesters, their effects during the mother’s first trimester is still unknown.

But a risk was also found in women who used other antihypertensive drugs and those with hypertension who did not take any antihypertensive medication.

Professor Allen Mitchell from Boston University says that – based on the available studies – it would appear reasonable to conclude that first-trimester exposure to ACE inhibitors poses no greater risk of birth defects than other antihiypertensives, and that it is the underlying hypertension that places the fetus at risk.