The effect of methadone treatment on the quantity and quality of human fetal movement

OBJECTIVE: To evaluate the effect of daily maternal methadone maintenance treatment on the quality and quantity of fetal movement. METHODS: At 34-37 weeks gestation, real-time ultrasound recordings were obtained from 17 methadone treated and 17 non-opioid-dependent mothers at two time points relative to the methadone mothers' daily dose of methadone. The first observation was just prior to the mother taking her daily dose (Time A) and the second was 1-h postdose (Time B). The incidence and pattern of fetal breathing movements (FBMs), fetal trunk movements (FTMs) and total fetal activity (TFA) were obtained from these ultrasounds. RESULTS: A time by group effect was found for measures of FBM and TFA, Fs(1,32)=6.06 and 4.94, P<0.05. At Time A and Time B for these measures t-tests showed no difference in the incidence of FBM (47.9% vs. 55.4%) and TFA (56% vs. 64%) at Time A between the methadone and comparison groups; however, at Time B the incidence of FBM (16.6% vs. 53.5%) and TFA (27% vs. 65%) was decreased for the methadone group. In addition, there was a between-group difference for two qualitative measures of fetal breathing. A slower rate of fetal breathing (40.3 vs. 47.2 breaths/min) and fewer FBMs per breathing episode (51.7 vs. 92.4) were found for the methadone group regardless of time since the mothers' daily dose. CONCLUSION: Taken together these results suggest that daily maternal methadone maintenance treatment altered both quantitative and qualitative measures of fetal activity that have been found to be related to normal fetal development.