Vaginal progesterone may lower preterm birth risk in twin pregnancy
Administration of vaginal progesterone reduces the risk of preterm birth at <30 to <35 weeks’ gestation and neonatal mortality in asymptomatic women with a twin gestation and sonographic short cervix (cervical length ≤25 mm) in the mid-trimester of pregnancy, a new study has shown.
Participants were obtained from six randomized controlled trials and included 303 mothers assigned to vaginal progesterone (n=159) or placebo (n=144). Seventy-four percent of the participants came from one study that analysed women with a cervical length between 20 and 25 mm.
Vaginal progesterone administration was associated with a significantly decreased risk of preterm birth at <33 weeks’ gestation (relative risk [RR], 0.69, 95 percent confidence interval [CI], 0.51–0.93; p=0.01) and neonatal death (RR, 0.53, 95 percent CI, 0.35–0.81) compared with placebo/no treatment. [Ultrasound Obstet Gynecol 2017;49:303-314]
Vaginal progesterone administration was also associated with decreased risk of preterm birth at <30, <32, <34, and <35 weeks’ gestation (RRs between 0.47 and 0.83), spontaneous preterm birth at <33 and <34 weeks’ gestation (RR, 0.67, 95 percent CI, 0.48–0.93 and RR, 0.71, 95 percent CI, 0.54–0.93), as well as other adverse perinatal outcomes such as perinatal death, respiratory distress syndrome, and composite neonatal morbidity and mortality.
In a subgroup analysis of women with short cervical length (10–20 mm), vaginal progesterone administration was associated with a significantly decreased risk of preterm birth at <33 weeks’ gestation (RR, 0.44, 95 percent CI, 0.22–0.87) and neonatal death (RR, 0.20, 95 percent CI, 0.05–0.86).
“Preterm birth is the most important factor determining neonatal morbidity and mortality among twins … A short cervix …. is an important risk factor for spontaneous preterm birth and has emerged as one of the strongest and most consistent predictors of preterm birth in asymptomatic women with singleton or twin gestations,” said the researchers.
These findings validate the efficacy of vaginal progesterone in reducing the risk of preterm birth and infant morbidity and mortality, and offer a probable alternative to other interventional measures (eg, prophylactic tocolysis, bed rest) that have not been proven effective in unselected twin gestations, noted the researchers.
Furthermore, the lack of long-term adverse neurodevelopmental, general health, and maternal outcomes highlights the potential maternal-foetal benefits of vaginal progesterone, they added, recommending further analysis for more conclusive recommendations that will help improve perinatal and neonatal outcomes and prevent preterm birth.