Pregnancy: Reducing risk

Last updated: Tuesday, September 27, 2022

When giving advice about prescribing medicines for a woman who is pregnant:

  • Consider non-pharmacological treatments and only prescribe drugs if essential.

  • Consider the period of gestation and, if possible, avoid all drugs during the first trimester.

  • Avoid known human teratogens.

  • Avoid newer drugs because usually there is little information on their effects in pregnancy.

  • Avoid polypharmacy.

  • Where appropriate, use the lowest effective dose for as short a period as possible.

However these strategies cannot be applied in every case, and the potential risk(s) of the medicine must always be carefully balanced against the potential benefit(s). For example, a woman stabilised on a newer antidepressant in her first trimester of pregnancy, may on balance benefit more from continuing with treatment rather than swapping to an older antidepressant with more safety information, or discontinuing treatment.

No drug has been demonstrated to be completely safe in pregnancy because it would not be ethical to conduct studies to prove the point. However, the drugs below are examples generally considered to carry minimal risk of adverse effects in pregnancy at normal therapeutic doses:

✦  Antacids✦  Paracetamol✦  Penicillins✦  Laxatives✦  Cephalosporins✦  Inhalers for asthma

Conversely, the following medicines are known to carry a higher risk in pregnancy. Refer to your Information sources to find out which common malformations or complications are associated with the following higher risk drugs:

✦  ACE inhibitors✦  Phenytoin✦  Isotretinoin✦  Alcohol✦  Tetracyclines✦  Warfarin