If you're carrying twins and your cervix is measuring short in the middle of pregnancy, your medical team is focused on one urgent goal: getting you as close to your due date as possible. A new, small study directly compared two strategies—placing a cervical pessary (a silicone ring that supports the cervix) versus using daily vaginal progesterone. The trial found that for the key measure of babies' health, complications occurred in 41% of babies in the pessary group versus 29% in the progesterone group. For the critical milestone of birth before 28 weeks, it was 19% with the pessary versus about 6% with progesterone.
It's crucial to understand what these numbers don't tell us. The differences weren't statistically significant, meaning they could easily be due to chance. The confidence intervals—the range where the true effect likely lies—were extremely wide. For the early birth outcome, the range stretched from a 63% lower risk with progesterone to a risk more than 27 times higher.
The study involved just 34 people at a single center in Australia and was stopped early because other, larger research elsewhere had already suggested pessaries weren't helpful for twin pregnancies. The researchers did not report on side effects or how tolerable the treatments were. Because the trial was small and halted prematurely, the evidence is considered low certainty.
For now, this research doesn't show that a pessary is harmful, nor does it prove progesterone is superior. It simply adds to a picture that, for twin pregnancies with a short cervix, the hoped-for benefit of a pessary over standard care hasn't materialized in this early look. More and larger studies would be needed to settle the question.
