Epidemiological surveys suggest that 30% to 60% of women will take at least one medication during pregnancy (Cordero & Oakley, 1983). It is difficult to estimate what proportion of pregnant women may be taking psychostimulants (amphetamines, amphetamine derivatives such as MDMA, or cocaine) during their pregnancy. In the National Household Survey on Drug Abuse conducted in the USA (Ebrahim & Gfroerer, 2003), 2.8% of pregnant women reported that they used illicit drugs, and one-tenth of these were using cocaine. In an Australian study describing characteristics of 96 infants born within a chemical dependence unit (Kelly, Davis & Henschke, 2000), 6% of mothers were using amphetamines alone and 66% were using intravenous drugs and receiving methadone maintenance. However, it was not stated what proportion of this latter group were using psychostimulants. Up to 10% of the Australian population has reported use of a psychostimulant and usage is increasing (Topp, Kaye et al., 2002). It is therefore likely that rates of concurrent psychostimulant use during pregnancy will increase.
Health professionals are often asked for advice on the safety of drugs (licit or illicit) during pregnancy and lactation. Generally, drug use during pregnancy is an issue that is associated with high levels of anxiety. Despite this, the numbers of drugs associated with teratogenicity are few. In order to best assess the risks of drug ingestion and make appropriate recommendations, it is necessary to have an understanding of:
- changes in maternal physiology during pregnancy;
- developmental phases of the embryo;
- the variable effect that the same drug may have at different times during the pregnancy; and
- mechanisms of drug transfer into breast milk.