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

INTRODUCTION: 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.