Pessary or Progesterone to Prevent Preterm delivery in women with a twin pregnancy and short cervical length

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Preterm birth, defined as birth before 37 weeks gestation, affects 22,000 pregnancies (7.5%) in Australia each year. While advances in neonatal care and treatments for preterm babies have greatly increased the chances of survival for even the smallest babies, preterm birth is still the leading cause of newborn death. Babies born before 37 weeks are also at risk for serious health problems including breathing difficulties, feeding problems, jaundice and effects on brain functions. Multiple pregnancy is a major risk factor for preterm birth, with 57% of twins born preterm compared to only 7% of singletons. Furthermore, 12% of twins are born before 32 weeks compared with only 2% of singletons. A short cervix, as measured by transvaginal ultrasound during the second trimester, is a powerful predictor of preterm birth. The risk of preterm delivery increases as the cervix shortens. When cervical length is less than 22 mm, women face a 20% probability of preterm delivery, which increases to 50% when the cervical length is less than 15 mm. Two currently available treatments used to reduce the incidence of preterm delivery in high risk women include the cerclage pessary and progesterone. Both of these interventions have been shown to effectively reduce the incidence of preterm birth in women with a short cervix. However, up until now, no study has directly compared the effectiveness of these two treatment options in women with twins. The purpose of this study is to directly compare the effectiveness of progesterone and cerclage pessaries in preventing preterm birth in women with a short cervix and twin pregnancy. Currently there is no standard treatment for short cervix in twin pregnancies. The standard treatment in singleton pregnancies is to offer progesterone. While the cerclage pessary is not widely used in Australia, it is widely used in Europe. A number of sites in Australia do use the cerclage pessary where they think it will be helpful. This study is similar to a larger one currently being conducted in the Netherlands. We will be watching that study closely to see if any of it’s outcomes inform us regarding the conduct of this study here in South Australia.