The effect of chronic methadone treatment on intra-uterine growth of the cynomolgus monkey (Macaca fascicularis).

A generally accepted management of heroin addiction during pregnancy is treatment with methadone, which reduces the complications of heroin addiction considerably. Reports in the literature are still contradictory, however, about the influence of methadone upon birthweight. In pregnant Cynomolgus monkeys (Macaca fascicularis) the effect of chronic treatment with rather high dosages of methadone upon birthweight was studied under standardized conditions. Birthweights were significantly lower in the methadone-treated animals.