Abstract
Objective This study aimed to compare the risk of recurrent spontaneous preterm birth (sPTB), as well as cerclage efficacy, between groups stratified by phenotype of the index sPTB.
Study Design This is a retrospective cohort study of women with a history of sPTB. Included were women with a history of singleton sPTB who received progesterone in a subsequent pregnancy. Multifetal gestations and abdominal cerclage were excluded. Exposure groups were based upon the presenting symptom that preceded their first sPTB and included painless cervical dilation (PCD), preterm premature rupture of membranes (PPROM), and painful dilation (preterm labor [PTL]). Primary outcome was delivery <34 weeks in a subsequent pregnancy. Secondary outcomes included delivery <28 and <37 weeks. Rates were compared using the Chi-square test. Multivariable Poisson regression was used to adjust for confounders.
Results A total of 723 women were included. A total of 114 (16%) presented with PCD, 305 (42%) with PPROM, and 304 (42%) with PTL in their first sPTB. Cerclage in subsequent pregnancy was highest in the PCD group (42%) when compared with the PPROM (16%) and PTL (12%) groups. Rates of sPTB <34 and 37 weeks were similar among the groups. After adjusting for confounders, PCD was found to significantly increase the risk of recurrent sPTB <28 weeks (incidence rate ratio: 3.46 [1.09–11.0]; p = 0.04). Of the 121 women who underwent cerclage, there were no significant differences in rates of sPTB between the clinical presentation groups.
Conclusion PCD as a specific phenotype of sPTB impacts recurrence of delivery before 28 weeks, but not at later gestational ages. In contrast, there was no significant association between clinical presentation of index sPTB and gestational latency in women who also underwent cerclage placement in a subsequent pregnancy. Our data suggest that clinical presentation is important with regards to recurrence of early sPTB, but not sPTB at later gestational ages.
Key Points
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Phenotype is critical to understanding PTB.
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Phenotype is associated with recurrent PTB.
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Painless dilation is associated with recurrent PTB.
Keywords
preterm birth - phenotype - clinical presentation - cerclage - recurrence
