Table 15. Treatment effects by subgroups according to the time from the start of treatment until birth.
| Outcome | Time (hours) | Included trials | MgSO4 | Control | RR | LCL | UCL | p† |
|---|---|---|---|---|---|---|---|---|
| Death or CP | 0 to <4 | 9,10,11,12 | 141/808 (17.5%) | 157/822 (19.1%) | 0.91 | 0.74 | 1.13 | 0.11 |
| 4 to <8 | 9,10,12 | 35/195 (17.9%) | 27/191 (14.1%) | 1.24 | 0.77 | 1.99 | – | |
| 8 to <12 | 9,10,12 | 15/95 (15.8%) | 29/84 (34.5%) | 0.49 | 0.27 | 0.87 | – | |
| 12 to <24 | 9,10,12 | 49/193 (25.4%) | 45/182 (24.7%) | 1.00 | 0.70 | 1.42 | – | |
| 24 to <36 | 9,12 | 25/70 (35.7%) | 15/57 (26.3%) | 1.34 | 0.78 | 2.29 | – | |
| 36+ | 9,11,12 | 117/446 (26.2%) | 116/394 (29.4%) | 0.92 | 0.73 | 1.14 | – | |
| Death (at any time) | 0 to <4 | 9,10,11,12 | 101/808 (12.5%) | 104/822 (12.7%) | 1.01 | 0.77 | 1.32 | 0.23 |
| 4 to <8 | 9,10,12 | 26/195 (13.3%) | 20/191 (10.5%) | 1.30 | 0.73 | 2.31 | – | |
| 8 to <12 | 9,10,12 | 15/95 (15.8%) | 26/84 (31.0%) | 0.55 | 0.31 | 1.00 | – | |
| 12 to <24 | 9,11,12 | 43/193 (22.3%) | 41/182 (22.5%) | 0.96 | 0.66 | 1.40 | – | |
| 24 to <36 | 9,12 | 24/70 (34.3%) | 14/57 (24.6%) | 1.38 | 0.79 | 2.41 | – | |
| 36+ | 9,11,12 | 112/446 (25.1%) | 110/394 (27.9%) | 0.93 | 0.74 | 1.17 | – | |
| Cerebral palsy | 0 to <4 | 9,10,11 | 40/558 (7.2%) | 53/551 (9.6%) | 0.75 | 0.50 | 1.12 | 0.77 |
| 4 to <12 | 9,10,12 | 9/186 (4.8%) | 10/162 (6.2%) | 0.71 | 0.30 | 1.68 | – | |
| 12+ | 9,10,11,12 | 13/320 (4.1%) | 11/282 (3.9%) | 1.13 | 0.47 | 2.68 | – | |
| Death or major neurosensory disability | 0 to <4 | 9,10,11,12 | 164/808 (20.3%) | 173/822 (21.0%) | 1.00 | 0.82 | 1.21 | 0.24 |
| 4 to <8 | 9,10,12 | 44/195 (22.6%) | 30/191 (15.7%) | 1.32 | 0.86 | 2.03 | – | |
| 8 to <12 | 9,10,12 | 20/95 (21.1%) | 30/84 (35.7%) | 0.64 | 0.39 | 1.05 | – | |
| 12 to <24 | 9,11,12 | 52/193 (26.9%) | 48/182 (26.4%) | 0.99 | 0.70 | 1.39 | – | |
| 24 to <36 | 9,12 | 29/70 (41.4%) | 18/57 (31.6%) | 1.27 | 0.79 | 2.03 | – | |
| 36+ | 9,11,12 | 126/446 (28.3%) | 125/394 (31.7%) | 0.94 | 0.76 | 1.16 | – |
Abbreviations: CP, cerebral palsy; LCL, lower confidence limit; RR, relative risk; UCL, upper confidence limit. The trials included are as follows: 9 = Australasian Collaborative Trial of Magnesium Sulphate (ACTOMgSO4), 10 = PREterm brain protection by MAGnesium sulphate (PREMAG), 11 = Magnesium and Neurologic Endpoints Trial (MAGNET), and 12 = MAGnesium sulphate for Prevention of Eclampsia (MAGPIE).
†p-values for heterogeneity (The heterogeneity p-value for 1-stage analyses is from Wald chi-square tests for the interaction between treatment and subgroup in a generalising estimating equation [GEE] model).