A multicenter, randomized trial examined the role
of serial transvaginal cervical length screening, with cerclage
placement for short cervical length, among women
with singleton gestations and prior spontaneous preterm
births at less than 34 weeks of gestation, including some
women who received 17a-hydroxyprogesterone caproate
(58). Women in this trial underwent serial cervical length
screening once every 2 weeks, starting at 16 weeks of
gestation until 23 weeks of gestation. If the length of
the cervix was noted to be between 25 mm and 29 mm,
the screening frequency was increased to once a week.
If the cervical length was less than 25 mm, women were
randomized to undergo cerclage or not to undergo cerclage.
The primary study outcome was preterm birth at
less than 35 weeks of gestation, for which no significant
difference was detected (relative risk [RR], 0.78; 95%
confidence interval [CI], 0.58–1.04) (58).