Table 4.
Summary of findings on the quality of evidence for primary and secondary outcomes
| Outcomes | Anticipated absolute effectsa (95% CI) | Relative effect (95% CI) | No. of participants (studies) | Quality of evidence (GRADE) | |
|---|---|---|---|---|---|
| Risk with placebo/no treatment | Risk with vaginal progesterone | ||||
| Preterm birth <37 weeks | 378 per 1000 | 242 per 1000 (189 to 306) | RR 0.64 (0.50 to 0.81) | 2976 (10 studies) | ⊕⊝⊝⊝ Very lowb,c |
| Preterm birth <34 weeks | 170 per 1000 | 106 per 1000 (72 to 57) | RR 0.62 (0.42 to 0.92) | 2886 (9 studies) | ⊕⊝⊝⊝ Very lowc,d |
| Preterm birth <28 weeks | 40 per 1000 | 45 per 1000 (28 to 71) | RR 1.12 (0.70 to 1.78) | 2835 (9 studies) | ⊕⊕⊕⊝ Moderatee |
| Respiratory distress syndrome | 129 per 1000 | 80 per 1000 (48 to 134) | RR 0.62 (0.37 to 1.04) | 1779 (6 studies) | ⊕⊝⊝⊝ Very lowc,f,g |
| Necrotizing enterocolitis | 10 per 1000 | 7 per 1000 (2 to 20) | RR 0.64 (0.22 to 1.90) | 1548 (4 studies) | ⊕⊕⊝⊝ Lowh |
| Intraventricular hemorrhage | 19 per 1000 | 21 per 1000 (11 to 42) | RR 1.11 (0.56 to 1.22) | 1589 (4 studies) | ⊕⊕⊝⊝ Lowh |
| Grade III/IV intraventricular hemorrhage | 3 per 1000 | 3 per 1000 (0 to 18) | RR 0.98 (0.14 to 6.94) | 1548 (4 studies) | ⊕⊕⊝⊝ Lowh |
| Neonatal sepsis | 27 per 1000 | 18 per 1000 (8 to 45) | RR 0.69 (0.29 to 1.68) | 1652 (5 studies) | ⊕⊝⊝⊝ Very lowc,h |
| Retinopathy of prematurity | 22 per 1000 | 29 per 1000 (12 to 67) | RR 1.32 (0.56 to 3.09) | 836 (2 studies) | ⊕⊕⊝⊝ Lowh |
| Bronchopulmonary dysplasia | 11 per 1000 | 21 per 1000 (7 to 62) | RR 1.97 (0.68 to 5.71) | 937 (3 studies) | ⊕⊕⊝⊝ Lowh |
| Periventricular leukomalacia | 2 per 1000 | 1 per 1000 (0 to 19) | RR 0.33 (0.01 to 8.03) | 837 (2 studies) | ⊕⊕⊝⊝ Lowh |
| Fetal death | 12 per 1000 | 13 per 1000 (6 to 26) | RR 1.05 (0.52 to 2.13) | 2522 (6 studies) | ⊕⊕⊝⊝ Lowh |
| Neonatal death | 24 per 1000 | 16 per 1000 (9 to 28) | RR 0.65 (0.36 to 1.15) | 2663 (7 studies) | ⊕⊕⊝⊝ Lowi |
| Perinatal death | 30 per 1000 | 27 per 1000 (17 to 43) | RR 0.90 (0.56 to 1.45) | 2522 (6 studies) | ⊕⊕⊝⊝ Lowh |
| Birthweight <1500 g | 55 per 1000 | 71 per 1000 (48 to 104) | RR 1.28 (0.87 to 1.89) | 1543 (4 studies) | ⊕⊕⊕⊝ Moderatej |
| Birthweight <2500 g | 275 per 1000 | 211 per 1000 (148 to 302) | RR 0.77 (0.54 to 1.10) | 1684 (5 studies) | ⊕⊕⊝⊝ Lowf,g |
| Admission to NICU | 207 per 1000 | 110 per 1000 (68 to 176) | RR 0.53 (0.33 to 0.85) | 1779 (6 studies) | ⊕⊕⊝⊝ Lowc,f |
| Use of mechanical ventilation | 126 per 1000 | 82 per 1000 (49 to 136) | RR 0.65 (0.39 to 1.08) | 1650 (5 studies) | ⊕⊕⊝⊝ Lowg,k |
| Patent ductus arteriosus | 21 per 1000 | 25 per 1000 (13 to 49) | RR 1.19 (0.61 to 2.36) | 1439 (3 studies) | ⊕⊕⊝⊝ Lowh |
| Threatened preterm labor or need for tocolysis | 232 per 1000 | 190 per 1000 (146 to 246) | RR 0.82 (0.63 to 1.06) | 1711 (5 studies) | ⊕⊕⊝⊝ Lowg,k |
| Use of antenatal corticosteroids | 310 per 1000 | 304 per 1000 (257 to 353) | RR 0.98 (0.83 to 1.14) | 1386 (2 studies) | ⊕⊕⊕⊕ High |
| Cesarean delivery | 259 per 1000 | 288 per 1000 (244 to 339) | RR 1.11 (0.94 to 1.31) | 1486 (3 studies) | ⊕⊕⊕⊝ Moderatej |
| Any maternal adverse event | 514 per 1000 | 519 per 1000 (457 to 591) | RR 1.01 (0.89 to 1.15) | 1458 (3 studies) | ⊕⊕⊕⊕ High |
| Discontinuation of treatment because of adverse events | 40 per 1000 | 56 per 1000 (36 to 86) | RR 1.38 (0.88 to 2.14) | 1558 (4 studies) | ⊕⊕⊕⊝ Moderatej |
| Preterm prelabor rupture of membranes | 110 per 1000 | 112 per 1000 (84 to 148) | RR 1.02 (0.77 to 1.35) | 1569 (4 studies) | ⊕⊕⊕⊝ Moderatej |
| Preeclampsia | 18 per 1000 | 27 per 1000 (11 to 66) | RR 1.48 (0.61 to 3.58) | 875 (2 studies) | ⊕⊕⊝⊝ Lowh |
| Gestational hypertension | 11 per 1000 | 14 per 1000 (4 to 44) | RR 1.19 (0.37 to 3.85) | 875 (2 studies) | ⊕⊕⊝⊝ Lowh |
| Gestational diabetes mellitus | 92 per 1000 | 103 per 1000 (69 to 154) | RR 1.12 (0.75 to 1.67) | 875 (2 studies) | ⊕⊕⊕⊝ Moderatej |
CI, confidence interval; NICU, neonatal intensive care unit; RR, relative risk
The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
Downgraded two levels due to very serious inconsistency: considerable heterogeneity (I2=75%), probably due to small-study effects.
Downgraded one level due to serious risk of bias: ≥50% of studies contributing to the outcome are at “high risk of bias” or “some concern of bias”.
Downgraded two levels due to very serious inconsistency: substantial heterogeneity (I2=66%), probably due to small-study effects.
Downgraded one level due to serious imprecision: 95% CI included no effect and is imprecise (lower and upper bounds <0.75 and>1.25, respectively).
Downgraded one level due to serious inconsistency: substantial heterogeneity (I2 ≥50%).
Downgraded one level due to serious imprecision: 95% CI included no effect and is imprecise (lower bound <0.75).
Downgraded two levels due to very serious imprecision: small total number of events; 95% CI included no effect and is imprecise (lower and upper bounds <0.75 and>1.25, respectively).
Downgraded two levels due to very serious imprecision: small total number of events; 95% CI included no effect and is imprecise (lower bound <0.75).
Downgraded one level due to serious imprecision: 95% CI included no effect and is imprecise (upper bound >1.25).
Downgraded one level due to serious inconsistency: moderate heterogeneity with some studies suggesting substantial benefit, and others no effect.