It is very uncertain whether the intervention changes preterm birth < 37 weeks (very low certainty).
Lower genital tract infection screening probably leads to lower preterm birth less than 37 weeks compared with no screening (moderate certainty).
Summary of findings table ‐ Midwife continuity of care models showed no clear difference in preterm birth (< 37 weeks) compared with other models of care (low certainty).
Summary of findings table ‐ Vitamin B12 supplementation showed no clear difference in preterm birth (< 37 weeks) compared with placebo/no vitamin B12 supplementation (low certainty).
It is very uncertain whether respiratory syncytial virus vaccine changes preterm birth compared with placebo (very low certainty).
Zinc supplementation showed no clear difference in preterm birth (< 37 weeks) compared with no zinc (with or without placebo) (low certainty).
Antihelminthics showed no clear difference in preterm birth (birth before 37 weeks of gestation) compared with control (low certainty).
Setting of BP measurement: self‐measurement showed no clear difference in preterm birth (birth before 34 completed weeks' gestation) compared with conventional clinic measurement (low certainty).
The review found no eligible studies for this question.
The review found no eligible studies for this question.
Antibiotics may leads to lower preterm birth < 37 weeks compared with no treatment (low certainty).
It is very uncertain whether progestogen changes preterm birth compared with placebo/no treatment (very low certainty).
The intervention leads to lower preterm birth (before 37 weeks' gestation) (high certainty).
The intervention leads to lower pregnancy with serious adverse outcome (composite including maternal… (high certainty).
Multiple micronutrients showed no clear difference in preterm births compared with control (iron with or without folic acid) (moderate certainty).
Vitamin D + calcium supplementation may leads to higher preterm birth (less than 37 weeks' gestation) compared with placebo or no intervention (low certainty).
Vitamin D + calcium + other vitamins and minerals showed no clear difference in preterm birth (less than 37 weeks' gestation) compared with calcium + other vitamins and minerals (but no vitamin D) (low certainty).
Vitamin D supplementation showed no clear difference in preterm birth (less than 37 weeks' gestation) compared with placebo or no intervention (low certainty).
A dose of vitamin D 601 IU or higher showed no clear difference in preterm birth compared with 600 IU or lower alone or with other nutrients (low certainty).
A dose of vitamin D 4000 IU/d or more showed no clear difference in preterm birth compared with 3999 IU/d or less alone or with any other nutrient (low certainty).