Prematurity is the main complication of pregnancy, and 15 million babies are born preterm worldwide each year.
Progesterone is a natural hormone produced by the ovaries in early pregnancy, and then later by the placenta. A decline in progesterone action is implicated as one of the causes of spontaneous preterm labor and delivery. Physicians worldwide have investigated in many studies whether vaginal progesterone administration to women with a mid-trimester sonographic short cervix reduces the rate of preterm birth.
Most major studies have been positive, until the publication of a study in February 2016. Now physicians and researchers have summarized the results of all studies in an article published today in the American Journal of Obstetrics & Gynecology and found that when all available information is considered in an individual patient data meta-analysis — the gold standard for summarizing clinical evidence — the results are clear.
Vaginal progesterone reduces the rate of preterm birth at <28, <30, <32, <34, <35, and <36 weeks. Moreover, it reduces the frequency of complications of prematurity and the number of babies weighing less than 1500 grams (also called very low birth weight).
The authors also reviewed cost-effectiveness studies, which showed that measuring the uterine cervix with ultrasound in the mid-trimester of pregnancy and giving vaginal progesterone to those with a short cervix is cost-effective (this strategy has been estimated to save the U.S. healthcare system approximately $500 million dollars per year). The researchers also reviewed the evidence of studies, which showed that when this approach is implemented in clinical practice, it reduces the rate of preterm birth in the “real world.”
“The findings of our meta-analysis of individual patient data, which includes all available trials, should reassure clinicians and professional/scientific organizations that vaginal progesterone is efficacious and safe for reducing preterm birth and neonatal morbidity and mortality in women with a sonographic short cervix,” commented Roberto Romero, MD, DMedSci, Chief of the Perinatology Research Branch, NICHD/ NIH/ DHHS, and Kypros Nicolaides, MD, professor and head of Obstetrics and Gynecology, Kings College, London, and head of the Fetal Medicine Foundation. “In addition, recent evidence assessing the implementation of universal cervical length screening in women with a singleton gestation and treatment with vaginal progesterone to those with a short cervix suggests that this intervention could contribute to a reduction in the rate of preterm birth and associated neonatal morbidity and mortality in the United States.”