Risk of recurrent spontaneous preterm birth: a systematic review and meta-analysis

Objective To determine the risk of recurrent spontaneous preterm birth (sPTB) following sPTB in singleton pregnancies. Design Systematic review and meta-analysis using random effects models. Data sources An electronic literature search was conducted in OVID Medline (1948–2017), Embase (1980–2017) and ClinicalTrials.gov (completed studies effective 2017), supplemented by hand-searching bibliographies of included studies, to find all studies with original data concerning recurrent sPTB. Study eligibility criteria Studies had to include women with at least one spontaneous preterm singleton live birth (