Fig. 2From: Efficacy and safety of pertussis vaccination for pregnant women – a systematic review of randomised controlled trials and observational studiesIncidence of preterm birth. Forest plots of studies with data on preterm birth as outcome. The first analysis included data from two RCTs with a total of 85 women in antental Tdap group and 66 women in the control. The second analysis included data from two cohort studies with a total of 26,363 women in antental Tdap group and 97,770 women in control with no pertussis vaccine. I-squared statistics for heterogeneity was 0% for both analysesBack to article page