Comparison 2. Methadone versus oral slow‐release morphine.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
2.1 Use of primary substance	1	48	Risk Ratio (M‐H, Fixed, 95% CI)	2.40 [1.00, 5.77]
2.2 Birth weight	1	48	Mean Difference (IV, Fixed, 95% CI)	124.00 [‐186.94, 434.94]
2.3 NAS mean duration	1	48	Mean Difference (IV, Fixed, 95% CI)	‐5.00 [‐10.97, 0.97]
2.4 Nicotine consumption	1	48	Mean Difference (IV, Fixed, 95% CI)	4.43 [‐1.47, 10.33]