Drugs and the fetus

Few drugs are licensed in pregnancy, and data on drug use in pregnancy are mainly retrospective and uncontrolled. Pregnancy exposure has increased recently to new classes of drugs, as they have been shown to be effective and well tolerated outside of pregnancy.

Anti-nausea therapies, H2-receptor and proton pump inhibitors appear to be safe. Metformin is being trialed for treatment in gestational diabetes and initial reports appear encouraging. Concern has been raised about statins in early pregnancy and should be avoided. New antiepileptic medication appears effective with low risk of abnormality. However, when combined with valproate, risks are still high. Selective serotonin reuptake inhibitors for depression appear to be effective, with likely low risk for teratogenesis, although neonatal behavioural syndrome following their use in the third trimester is a concern. Angiotensin II inhibitors should be avoided in the second and third trimesters of pregnancy. Smoking cessation programmes need to be reevaluated.

Information about safety of drugs and caution about prescribing in pregnancy should continue. Until large clinical trials are performed, the risk/benefit ratio of drugs during pregnancy will remain uncertain.