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17P Cuts Preterm Birth if No Cerclage


 

Major Finding: In women with a cervical length of 15-24 mm, 17P was associated with statistically significant decreases in both preterm birth at less than 24 weeks (OR, 0.11) and perinatal mortality (OR, 0.18). There was no significant effect of 17P in women with a cervical length of less than 15 mm.

Data Source: Secondary analysis of 300 patients in the Vaginal Ultrasound Cerclage Trial.

Disclosures: The study was funded by the National Institute of Child Health and Human Development. Dr. Berghella disclosed no conflicts of interest.

CHICAGO — The effect of 17-alpha-hydroxyprogesterone caproate on preterm birth varies depending on the presence or absence of cerclage in high-risk women, according to a planned secondary analysis of the Vaginal Ultrasound Cerclage Trial.

In women with prior spontaneous preterm birth and a cervical length of less than 25 mm, the hormone had no effect if cerclage was present, but significantly reduced preterm births at less than 24 weeks and perinatal mortality if cerclage was absent, Dr. Vincenzo Berghella reported at the annual meeting of the Society for Maternal-Fetal Medicine.

The use of 17-alpha-hydroxyprogesterone caproate (17P) had no effect on the primary outcome of preterm birth at less than 35 weeks in either the cerclage or no-cerclage groups.

Among the 148 women randomized to cerclage, the primary outcome occurred in 30% of the 47 women receiving 17P and in 34% of the 101 women with no 17P (odds ratio, 0.84).

Among the 152 women with no cerclage, the primary outcome occurred in 39% of the 52 women who received 17P and in 44% of the 100 women with no 17P (OR, 0.80). Women given 17P in either group received an average of 11 injections, beginning at an average gestational age of 18-19 weeks (range, 16-28 weeks).

In the presence of cerclage, the use of 17P had no significant effect on the outcomes of preterm birth at less than 24 weeks (OR, 0.60); less than 28 weeks (OR, 0.46); less than 32 weeks (OR, 0.62); or less than 37 weeks (OR, 1.29). The use of 17P in the presence of cerclage also had no significant effect on perinatal death (OR, 0.62), said Dr. Berghella, professor of ob.gyn. at Jefferson Medical College in Philadelphia.

In the absence of cerclage, the use of 17P had a significant effect only on preterm birth at less than 24 weeks, occurring in 2% of women given 17P vs. 20% with no 17P (OR, 0.08), and on perinatal death, occurring in 4% of women given 17P and 23% with no 17P (OR, 0.14).

Because cervical length was a significant predictor of preterm birth in both groups in a logistic regression analysis, the researchers analyzed the effect of 17P using different cervical length cutoffs. In women with a cervical length of 15-24 mm, 17P was associated with statistically significant decreases in both preterm birth at less than 24 weeks (OR, 0.11) and perinatal mortality (OR, 0.18), while there was no significant effect of 17P in women with a cervical length of less than 15 mm, Dr. Berghella said.

During a discussion of the findings, an attendee said the study provides a clear clinical effect of 17P, but that the researchers may have “de-powered” the study by separately analyzing the women based on cerclage status. Dr. Berghella said the researchers felt that women who receive cerclage are different from those who do not, and that the design was influenced by the original analysis showing that cerclage had an influence on preterm birth (Am. J. Obstet. Gynecol. 2009;201:375:e1-8).

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