What is the optimal gestational age for history-indicated cerclage placement?

We estimated the optimal gestational age for placement of a history-indicated cerclage in a retrospective cohort study of pregnancies during the period between 1994 to 2007. Pregnancies were divided into two groups: group 1, cerclage <14 weeks (N = 83), and group 2, cerclage >or=14 weeks (N = 59). The primary outcome was spontaneous preterm birth (SPTB) <35 weeks. Parametric and nonparametric tests were performed where appropriate. One hundred forty-two pregnancies by 130 women were included. Demographic characteristics were similar between groups. The median gestational age at cerclage was 12 weeks (group 1) and 15 weeks (group 2). There was no difference in the primary outcome, incidence of SPTB <35 weeks (17% versus 20%; P = 0.59) between groups 1 and 2, respectively. Likewise, the secondary outcomes, mean gestational age at birth (38 versus 37 weeks; P = 0.96), incidence of low birth weight (28% versus 23%; P = 0.50), and the incidence of preterm premature rupture of membranes (17% versus 18%; P = 0.89) were similar between groups. No other gestational age cutoff was predictive of SPTB <35 weeks using a receiver operator characteristic curve (13 to 17 weeks; area = 0.52; P = 0.64). Gestational age of history-indicated cerclage placement was not associated with a significant effect on preterm birth in high-risk women. The optimal gestational age for placement of a history-indicated cerclage is probably 12 to 14 weeks, after screening for fetal anomalies and aneuploidy.