Substance abuse in pregnancy.

The number of women who abuse drugs during pregnancy is unknown, but as many as 375,000 infants may be affected. Although some substances appear to result in less damage than others, it is impossible to differentiate individual effects because of the common use of multiple substances. The potential for synergy among substances with similar physiologic effect is an additional factor. The immediate perinatal effects of substance abuse are often obvious; it is the long-term effects that we have only recently begun to examine. These long-term effects will involve both the individual and society.