Table 5.
Crude and adjusted (IP-weighted) odds ratios of adverse neonatal and pregnancy outcomes associated with prenatal exposure to methadone early (alone) or late (alone) in pregnancy compared with buprenorphine.
| Exposure to OAT in early pregnancy only | Exposure to OAT in late pregnancy only | |||
|---|---|---|---|---|
| Crude OR (95% CI) | Weighted OR (95% CI) | Crude OR (95% CI) | Weighted OR (95% CI) | |
| Neonatal outcomes | ||||
| Preterm birth (<37 weeks) | ||||
| Buprenorphine | Ref. | Ref. | Ref. | Ref. |
| Methadone | 1.52 (0.38, 6.03) | 1.87 (0.33, 10.67) | 5.11 (1.14, 22.90) | 7.74 (1.26, 47.41) |
| Low birthweight (<2500 g) | ||||
| Buprenorphine | Ref. | Ref. | Ref. | Ref. |
| Methadone | 2.51 (0.48, 13.17) | 0.80 (0.09, 6.93) | 2.69 (0.40, 18.18) | 9.15 (0.88, 95.46) |
| Neonatal Intensive Care Unit Admission (NICUa) | ||||
| Buprenorphine | Ref. | Ref. | Ref. | Ref. |
| Methadone | 2.38 (0.70, 8.13) | 1.98 (0.43, 9.17) | 1.35 (0.39, 4.65) | 1.42 (0.31, 6.53) |
| Neonatal abstinence syndrome (NAS) | ||||
| Buprenorphine | Ref. | Ref. | Ref. | Ref. |
| Methadone | 0.66 (0.17, 2.66) | 0.42 (0.08, 2.28) | 1.91 (0.49, 7.41) | 2.61 (0.51, 13.36) |
| Respiratory symptoms | ||||
| Buprenorphine | Ref. | Ref. | Ref. | Ref. |
| Methadone | 1.70 (0.36, 8.06) | 1.28 (0.22, 7.52) | 0.93 (0.19, 4.50) | 1.18 (0.19, 7.32) |
| Feeding difficulties | ||||
| Buprenorphine | Ref. | Ref. | Ref. | Ref. |
| Methadone | 0.32 (0.08, 1.28) | 0.14 (0.03, 0.58) | 1.26 (0.33, 4.88) | 2.76 (0.68, 11.27) |
| Small for gestational age | ||||
| Buprenorphine | Ref. | Ref. | Ref. | Ref. |
| Methadone | 5.11 (1.70, 15.40) | 4.86 (1.39, 17.01) | 0.21 (0.07, 0.67) | 0.23 (0.06, 0.87) |
| Maternal and obstetrical complications | ||||
| Length of maternal hospital stay (>7 days)c | ||||
| Buprenorphine | Ref. | Ref. | Ref. | Ref. |
| Methadone | 2.63 (0.74, 9.39) | 2.66 (0.55, 12.90) | 1.31 (0.37, 4.66) | 1.42 (0.30, 6.71) |
| Caesarean delivery | ||||
| Buprenorphine | Ref. | Ref. | Ref. | Ref. |
| Methadone | 3.04 (0.86, 10.70) | 2.69 (0.62, 11.78) | 0.19 (0.05, 0.66) | 0.27 (0.07, 1.15) |
Abbreviations: IP = inverse probability; OR = odds ratios; CI = confidence intervals.
Counts and percentages of events were not reported due to small numbers (<11) for most of the outcomes of interest.
Stabilized inverse-probability treatment weights (IPTWs) of early and late exposure were computed with the numerator model adjusting for baseline covariates (i.e., maternal age, race, year of birth, multiple gestation, pre-existing comorbid conditions, and healthcare resource utilization at baseline), and the denominator model adjusting for additional time-varying comedication use, substances use, and markers of OUD severity. Previous exposure history was included in the models for late exposure. Infant sex was included for adverse neonatal outcomes. A product of stabilized IPTWs for early and late exposure was used in outcome models.
Missing values were ≤0.5% and only complete cases were analyzed.