Cervical Length Screening Did Not Reduce Rates of Preterm Births

NATIONAL HARBOR, Md. — Among pregnant women at low risk for preterm delivery, universal transvaginal ultrasound (TVU) cervical length screening did not reduce rates of preterm birth, a multicenter non-blinded randomized trial from Italy showed.

Rates of preterm birth at less than 37 weeks’ gestation were similar between groups: 7.5% of those who underwent screening versus 8.7% of those who did not undergo screening, reported Gabriele Saccone, MD, PhD, of the Università degli Studi di Napoli Federico II in Naples, Italy, during the Society for Maternal-Fetal Medicine annual meeting.

There were also no significant differences in the incidence of preterm birth at less than 34, 32, 30, 28, and 24 weeks of gestation.

Cynthia Gyamfi-Bannerman, MD, MS, department chair of obstetrics, gynecology, and reproductive sciences at the University of California San Diego, told MedPage Today that this research was important “because we still have not addressed the best way to identify women with a short cervix.”

However, she also noted that Saccone didn’t report how the control group was assessed, which would have been helpful information.

“The numbers were likely a bit small in terms of outcomes to know if routine transvaginal cervical length screening made a difference, since all the point estimates suggested a benefit, but there was no statistical difference,” Gyamfi-Bannerman said. “I think what this tells us is that it’s probably okay to screen for preterm birth risk without using transvaginal cervical length if not readily feasible in an ultrasound unit, but I would not change practice prior to seeing the peer-reviewed manuscript.”

The study took place from July 2018 through December 2022 at the University of Naples Federico II and the University of Campania Luigi Vanvitelli. Inclusion criteria included singleton gestation between 18 and 23 weeks and no previous spontaneous preterm birth.

During routine anatomy scan from 18 through the end of 23 weeks’ gestation, 675 participants were randomized to screening (mean age 31.6, 84.6% white) and 659 were randomized to no screening (mean age 32.1, 84.1% white). Maternal characteristics were also similar for smoking status, gestational age at randomization, and body mass index.

Women in the screening group received a single TVU cervical length measurement. Those with a cervical measurement of 25 to 30 mm were screened again 1 week later.

The vast majority of women in the screening group had a ≥30-mm cervix (94.2%). Only 1.9% with a cervix ≤25 mm were randomized to screening and were offered 200-mg vaginal progesterone daily. In this group, 11 women received a cervical pessary and two underwent cervical cerclage, Saccone said.

For perinatal metrics, the screening group had numerically lower rates of admission to the neonatal intensive care unit, neonatal death, second trimester pregnancy loss, and composite perinatal outcomes, as well as slightly higher birth weights, compared with the control group, though none of the differences were statistically significant.

Of the women in the screening group, 5% experienced pelvic discomfort, and 1.6% experienced pelvic pain. None had vaginal bleeding.

The researchers noted that the study was underpowered for the primary outcome of preterm birth at less than 37 weeks’ gestation, and larger studies are needed.