GRAPEVINE, TEX. – or a composite measure of adverse neonatal outcomes, according to a randomized, open-label study.
“The Arabin pessary should not be used to prevent preterm birth in women with twin pregnancy,”, dean of health sciences at the University of Bristol (England), said at the Pregnancy Meeting.
“Preterm birth is very common in twin pregnancy” and leads to “excess neonatal mortality amongst twins,” Dr. Norman said at the meeting, which is sponsored by the Society for Maternal-Fetal Medicine. “Preventing preterm birth is important for both singletons and twins, but it could have even more benefits in twins.”
Emerging evidence has suggested that the Arabin cervical pessary may be useful for the prevention of preterm birth in women with singleton pregnancy and a short cervix. In twin pregnancy, data are more limited.
Therandomized 813 women with twin pregnancy to a cervical pessary or standard care. Although the pessary had no impact on preterm birth overall, among women with cervical length of less than 38 mm, those who received a pessary were less likely to have preterm birth. The sample size was small, however, and the average length of the cervix in ProTwin differed from that in a previous U.K. study, Dr. Norman said.
Inspired by the study, Dr. Norman and coinvestigators conducted, a multicenter, open-label, randomized, controlled trial to further study whether a certain cervical length threshold was associated with benefit of a cervical pessary in preventing preterm birth. The trial included women with twin pregnancy who had a cervical length ultrasound between 18 and 20 weeks and 6 days of gestation. Women with a cervical length of 35 mm or less were eligible for randomization. Patients received an Arabin pessary plus standard care or standard care alone.
The primary obstetric outcome was spontaneous onset of labor leading to delivery before 34 weeks and 6 days of gestation. The primary neonatal outcome was a composite of outcomes – stillbirth, neonatal death, periventricular leukomalacia, respiratory morbidity, intraventricular hemorrhage, necrotizing enterocolitis, or sepsis – measured up to 28 days after the expected date of delivery.
The investigators randomized 503 women in all, including 250 to the pessary and 253 to standard care. Both groups had similar baseline characteristics, Dr. Norman said. The average age was about 33 years, and the average cervical length was about 29 mm. A total of 20% had monochorionic diamniotic pregnancies, and 80% had dichorionic pregnancies. The researchers excluded women with monochorionic monoamniotic pregnancies. In the pessary group, 16 patients declined the intervention, and 4 were unable to have the pessary inserted.
Spontaneous preterm birth occurred in 18% of patients in the Arabin pessary group, compared with 21% in the standard treatment group. The adjusted odds ratio, 0.87, was not statistically significant. In subgroups of patients with monochorionic pregnancy, cervical length less than 28 mm, or cervical length less than 25 mm, there was no significant benefit.
The composite measure of adverse neonatal outcomes also did not significantly differ between the groups. None of the individual components indicated benefit of the pessary either, Dr. Norman said.
In subgroup analyses, odds ratios for adverse neonatal outcomes were “tending towards harm for the Arabin pessary group ... although clearly none of them conferring statistical significance,” she said. Among women with cervical length less than 28 mm, a primary neonatal outcome – at least one of the adverse outcomes – occurred in 23% of patients in the Arabin pessary group, compared with 20% of patients in the standard care group.
Approximately two-thirds of patients found pessary insertion painless or slightly uncomfortable, whereas about 10% described the experience of device fitting as very uncomfortable, and about 1% described it as the worse pain imaginable.
“Since we started STOPPIT-2, in addition to ProTwin, another three studies have been published on the efficacy of the Arabin pessary in twins,” said Dr. Norman. Combined data show no significant effect of the pessary on preventing preterm birth in twin pregnancy. Still, the meta-analysis does not rule out the possibility that there could subgroups of patients who may benefit from the intervention, Dr. Norman said.
STOPPIT-2 was funded by the National Institute for Health Research (NIHR) in the United Kingdom. Dr. Norman chaired the UK National Institute for Health and Care Excellence guidelines on preterm labor and birth in 2015. In addition, Dr. Norman was a member of a GlaxoSmithKline data safety and monitoring group for a trial of a preterm birth prevention agent, has consulted for Dilafor, and has received research grants for preterm birth prevention from the U.K. Medical Research Council, NIHR, and Tommy’s: Together, for every baby charity.
SOURCE: Norman JE et al. Am J Obstet Gynecol. 2020 Jan;222(1):S756. Abstract LB 1.