Duration of methadone maintenance treatment during pregnancy and pregnancy outcome parameters in women with opiate addiction.

OBJECTIVES: Methadone maintenance treatment (MMT) is the standard treatment of choice for pregnant opiate addicts; however, data on newborn outcomes are contradictory. We studied the effect of the timing of starting MMT and of MMT related drug abstinence on the outcome of newborns of former and current opiate-addicted pregnant women.
METHODS: All babies (excluding repeated deliveries) of all pregnant women who were admitted to 1 MMT clinic between 1993 and 2008 were studied. Former opiate-addicted women who became pregnant while already on MMT (full-pregnancy MMT, FP-MMT) and opiate-addicted women who only started MMT during pregnancy (partial-pregnancy MMT, PP-MMT) were retrospectively compared for birth weight and gestational age of newborns. Abstinence was defined as negative urine sample results for opiates, cocaine, amphetamines, benzodiazepine and cannabis during the month before delivery.
RESULTS: We examined 59 newborn babies: 14 in the FP-MMT group and 45 in the PP-MMT group. The mean birth weight was 2733.2 ± 392.0 g versus 2240.0 ± 680.4 g respectively (F[1] = 6.6, P = 0.01). Abstinence was determined among 73.3% of the FP-MMT and 28.6% of the PP-MMT (P = 0.004). Gestational age was higher in the abstinence (37.9 ± 2.8 weeks) versus no-abstinence group (35.8 ± 4.6 weeks; F[1] = 4.4, P = 0.04).
CONCLUSIONS: The best pregnancy outcome, characterized by a higher gestational and birth weight, was associated with a longer duration on MMT and substance abstinence, emphasizing the importance of MMT stabilization before and during pregnancy.