Tracy A. Manuck, MD, Dr. Manuck is Assistant Professor of Maternal-Fetal Medicine at the University of Utah Health Sciences Center and Co-Director of the University of Utah Prematurity Prevention Clinic in Salt Lake City, Utah.
The author reports that she receives grant support from the Eunice Kennedy Shriver National Institute of Child Health and Human Development.
Progesterone in multiple gestations Although several formulations of progesterone—including IM 17-alpha hydroxyprogesterone caproate, micronized progesterone, and progesterone suppositories—have been studied, no randomized trial data have demonstrated a reduction in PTB or neonatal morbidity.26–29 Individual patient-level data from a meta-analysis of vaginal progesterone in the setting of multiple gestations with a short cervical length suggest trends toward a reduced rate of PTB before 33 weeks’ gestation (relative risk [RR], 0.70; 95% CI, 0.34–1.44) and lower composite neonatal morbidity and mortality (RR, 0.56; 95% CI, 0.30–0.97).30
Mechanical strategies in multiple gestations No randomized data suggest that a pessary is effective in multiple gestations. In one study of 813 multiple gestations in the Netherlands, women were randomly assigned—regardless of cervical length—to receive a pessary at 16 to 20 weeks versus standard care; no difference in adverse perinatal outcomes was detected between groups.31
As for cerclage, although data are limited, some studies suggest that placement of a cerclage in twin gestations with cervical shortening may increase the rate of PTB.32
Bottom line for multiples Although women carrying multiple gestations are at higher risk for PTB, data are extremely limited. At present, data do not support routine use of cerclage for a short cervix—and some suggest possible harm. Vaginal progesterone or placement of a pessary may be of benefit but should be used with caution and with the understanding that data are sparse.
CASE RESOLVED You counsel your nulliparous patient that she has an elevated risk of PTB, based on her cervical length of 18 mm at 20 weeks’ gestation, and evaluate her clinically for evidence of preterm labor. Apart from the short cervix, her examination is unremarkable. You offer her nightly vaginal progesterone suppositories and schedule a visit to reevaluate her cervix in 1 week. If cervical dilation or prolapsing membranes are noted before the age of fetal viability, you will consider placing a “rescue” cervical cerclage.
Had this patient experienced a prior PTB, you would first ensure that she is taking IM 17-alpha hydroxyprogesterone caproate. It also would be reasonable to place an ultrasound-indicated cerclage or begin vaginal progesterone suppositories. Although data are limited on concomitant use of IM and vaginal progesterone, some experts may consider it, on an experimental basis, for patients with a short cervix and a prior PTB.
If this patient were carrying a twin gestation, vaginal progesterone would still be a consideration, provided she is counseled about the limited evidence of its efficacy in this setting. Cerclage would not be appropriate, given the possible risk of harm.
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