Recurrence of second trimester miscarriage and extreme preterm delivery at 16–27 weeks of gestation with a focus on cervical insufficiency and prophylactic cerclage

The objective of this study was to describe recurrence rates of second trimester miscarriage and extreme preterm delivery by phenotype and use of prophylactic cerclage in a register‐based cohort. Material and methods We included women with a first second trimester miscarriage or extreme preterm delivery (16 +0 to 27 +6 gestational weeks) in Denmark in 1997–2012 ( n  =   9602) by combined use of the Danish Medical Birth Register and the Danish National Patient Register. Eight phenotypes were identified by ICD ‐10 codes in a hierarchy with the following sequence: major fetal anomaly, multiple gestation, uterine anomaly, placental insufficiency, antepartum bleeding, cervical insufficiency, preterm premature rupture of membranes, and intrauterine fetal death. Recurrence rate after a second trimester miscarriage/spontaneous delivery in the period was calculated based on the register data. In cervical insufficiency outcome was stratified by prophylactic cerclage applied <16 weeks of gestation. Results Overall recurrence rate was 7.3% ( n  =   452), a rate that differed by phenotype from <5% (fetal anomaly, multiple gestations, intrauterine fetal death) to 21% (cervical insufficiency). In women with cervical insufficiency the recurrence rate was 28% without cerclage; vaginal cerclage was associated with a significant reduction [adjusted odds ratio ( OR ) 0.47; 95% CI 0.29–0.76] and abdominal cerclage with an even greater reduction (adjusted OR 0.14; 95% CI 0.03–0.61). Conclusions The overall recurrence rate of second trimester miscarriage or extreme preterm delivery was 7%, but it differed significantly by phenotype. The highest rate, 28%, was found in cervical insufficiency, and prophylactic cerclage was associated with a significant reduction in recurrence.