General practitioners will be well aware of the need to review the use of drugs in pregnant women. Some drugs can potentially harm the developing baby and cause abnormalities of structure (congenital malformations) or function (disturbances of growth and development). Common drugs which can potentially cause serious fetal problems include isotretinoin, valproate, and warfarin.
The topic of “drugs in pregnancy” has been well addressed in recent publications (see references below), but clinicians need to be very aware of an important caution regarding this topic.
The main period of risk in which a developing baby can be harmed by maternal drugs occurs early in pregnancy. The development of fetal organs is complete by 10 weeks gestation, and crucial development has already occurred by the time the woman or her doctor has confirmed the pregnancy. This means that a review of her medications at that stage is too late: the damage may have already been done, and it cannot be reversed. For this reason, the use of “drugs in pregnancy” must be reviewed before pregnancy.
A clinical review of drugs in pregnancy should be done before a woman conceives, and be a routine matter in the care of any woman of reproductive age. This is particularly important in woman taking medications such as isotretinoin, valproate, or warfarin which are known to cause fetal malformations. The management of contraception should be incorporated into the decision to start prescribing such medications, and must be reviewed with every repeat prescription.
If a woman becomes pregnant while taking a medication which can cause fetal malformations, advice should be sought immediately from local specialist obstetric or genetic services so that the actual risk to the fetus can be clarified.
Kennedy D, Medications in Pregnancy and Lactation, Australian Doctor 13 January 2012 (http://www.australiandoctor.com.au/cmspages/getfile.aspx?guid=02fbda06-f211-49d5-bf08-6da549849cbb)
Kennedy D, The safety of drugs in pregnancy and breasts feeding, O&G Magazine 16 (2):47-49, 2014 (https://www.ranzcog.edu.au/RANZCOG_SITE/media/DOCMAN-ARCHIVE/The%20safety%20of%20drugs%20in.pdf).