Risks of drugs

• Most drugs will cross placenta and reach the unborn child
• Introduces risk of teratogenicity and resultant structural or functional embryological defects

NSAIDs - Block prostglandins, which in pregnancy are important:

• They maintain the ductus arteriosus
• Soften the cervix and stimulate uterine contractions

NSAIDs are avoided in pregnancy unless necessary (e.g. RA), particularly in 3rd trimester as they can cuase premature closure of the ductus arteriosus and delay labour

Beta-Blockers

Labetalol is the most frequently used beta-blocker in pregnancy, and is first-line for high blood pressure caused by pre-eclampsia.

Beta-blockers can cause:

• Fetal growth restriction
• Hypoglycaemia in the neonate
• Bradycardia in the neonate

ACE inhibitors and ARBs

In the fetus, they mainly affect the kidneys, and reduce the production of urine (and therefore amniotic fluid). The other notably effect is hypocalvaria, which is an incomplete formation of the skull bones.