Table 2

Summary estimates from random effects analyses

Adverse outcomeNumber of studiesSummary estimate
OR (95% CI)
I2 (%)Prediction interval
Preterm birth
 Adjusted51.90 (1.14 to 3.19)64.50.36 to 10.03
 Unadjusted181.55 (1.21 to 1.99)61.10.72 to 3.35
Low birth weight
 Adjusted41.48 (0.79 to 2.77)49.50.14 to 15.70
 Unadjusted81.66 (1.12 to 2.48)72.70.51 to 5.38
Premature rupture of membrane91.41 (1.02 to 1.92)59.20.64 to 3.11
Spontaneous abortion*3NANANA
Perinatal mortality92.16 (1.35 to 3.46)40.30.69 to 6.74
Ophthalmia neonatorum64.21 (1.36 to 13.04)58.00.17 to 104.58
  • *Each study had a different design, therefore it was not appropriate to report a summary estimate for this outcome.

  • NA, not applicable.