Preterm birth is the delivery of a baby before 37 weeks of gestation period. A normal gestation period lasts about 40 weeks. In the case of preterm delivery, premature birth occurs and it increases the risk of infant mortality, morbidity, and long-term neurodevelopmental issues.
In a recent study published in BMJ Journal, researchers have revealed the comparative effectiveness of cervical pessary and vaginal progesterone in preventing preterm birth. This study was focused on pregnant women with a singleton pregnancy, no prior history of premature birth before 34 weeks, and a short cervix of 35 mm or less.
This was an open label, multicentre, randomized controlled trial conducted in 20 hospitals and 5 obstetric ultrasonography clinics in the Netherlands. Women with a healthy singleton pregnancy and an asymptomatic short cervix (35 mm or less) between 18 and 22 weeks of gestation were considered eligible for this study.
In the timeframe of this study between July 1, 2014, and March 31, 2022, 612 participant women were randomly divided into two groups. 303 of them received a cervical pessary and the other 309 received vaginal progesterone 200 mg daily.
This process continued until 36 weeks of gestation period or earlier if membranes ruptured, infection signs appeared, or preterm labor began.
The primary outcome measure of this study was a composite of adverse perinatal events, and secondary outcomes included rates of (spontaneous) preterm birth before 28, 32, 34, and 37 weeks. Researchers planned a predefined subgroup analysis in which they focused on women with cervical lengths of 25mm or less.
In the cervical pessary group, 19 out of 303 women, that is 6%, experienced the composite adverse perinatal outcome. 17 out of 309 women, that is 6% in the progesterone group, also faced this outcome. The crude relative risk was 1.1 (with a 95% confidence interval ranging from 0.60 to 2.2). As for spontaneous preterm births, the rates were almost the same for both groups.
In the subgroup of women with cervical lengths of 25mm or less, spontaneous preterm birth before 28 weeks was more common in the cervical pessary group than progesterone. Also, adverse perinatal outcomes seemed more frequent in the pessary group.
The results of this study show that for women with a singleton pregnancy, no prior early preterm birth, and a short cervix (35mm or less), using vaginal progesterone was better than using cervical pessary in preventing preterm birth. The pessary seemed less effective in the subgroup with an even shorter cervix (25 mm or less).
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