Cervical cerclage placed before 14 weeks gestation in women with one previous midtrimester loss: A population‐based cohort study

Background Cervical cerclage is used in an attempt to reduce recurrence risk of preterm birth, but evidence for use is limited. Aims To compare pregnancy outcomes among women with a single previous midtrimester delivery when managed with or without a cervical cerclage. Materials and methods Population‐based cohort study of all women in New South Wales, Australia with a singleton pregnancy ending in birth/miscarriage ≥14 and <28 weeks, between 2003 and 2011. Modified Poisson regression was used to compare outcomes in the next subsequent pregnancy, for women with a cerclage inserted <14 weeks, and those without cerclage. The primary outcome was gestational age <37 weeks at birth/miscarriage in the next pregnancy. Secondary outcomes included: maternal morbidity, preterm prelabour rupture of membranes ( PPROM ), stillbirth/neonatal death and composite neonatal morbidity for liveborn infants ≥28 weeks. Adjusted risk ratios ( ARR ) and 95% confidence intervals ( CI ) were determined. Results Five thousand, six hundred and ninety‐eight births/miscarriages were potential index deliveries. Of these, 2175 women had an eligible subsequent pregnancy: 108 received cerclage at <14 weeks gestation, 2067 did not. Women with cerclage were significantly more likely to deliver <37 weeks than those without (39.8% vs 19.3%, ARR 1.92, 95% CI 1.48–2.48), and had increased risks of PPROM ( ARR 4.38, 95% CI 2.62–7.32) and stillbirth/neonatal death ( ARR 2.20, 95% CI 1.02–4.73). Following cerclage, liveborn infants ≥28 weeks had double the risk of severe morbidity ( ARR 2.54, 95% CI 1.55–4.16). Conclusions In women with a single previous midtrimester delivery, cervical cerclage <14 weeks gestation in subsequent pregnancy was associated with worse pregnancy outcomes.