Objective: The aim of this study is to better understand anticipated changes in daily methadone doses as a guide for prescription during pregnancy.
Methods: This retrospective case series involved a single cohort longitudinal design of 139 consecutively chosen women who began methadone therapy before 26 completed gestational weeks. Changes in the single daily dose were based on a standard opiate withdrawal scale and determined from early pregnancy until 6 weeks postpartum.
Results: As gestation advanced, the methadone dose increased (86%) rather than remained the same (8%) or decreased (7%). This gradual increase in daily dose during pregnancy (mean increase = 24 mg, 95% confidence level = 20-28 mg) was statistically significant (p < .001) regardless of the initial maintenance dose. By the sixth postpartum week, most subjects (85%) took within 10 mg of their dose at delivery (mean change in dose = -4 mg, 95% confidence interval = -6 to -2 mg).
Conclusions: Daily doses of methadone increased until the third trimester, then remained essentially unchanged through the sixth postpartum week.
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