Globally, more than 15 million babies are born preterm each year and around 1 million of these die from associated complications. Many of those that live develop lifelong learning disabilities and visual and hearing problems. The risk of cerebral palsy (CP) for instance is 70 times greater in babies born 28 weeks gestation and some 90% of infants born before 30 weeks gestation show brain abnormalities on MRI. Thus, being able to predict which babies are at risk form being born prematurely would help enormously with developing strategies and treatments to delay premature birth. The picture for twins is even bleaker. The rate of preterm birth in twins is almost 10 times higher than in singletons.
Genesis Research Trust-funded researcher Lindsay Kindinger conducted what is known as a meta-analysis study of published data on twin births. It is already known that cervical length measurement can be used to predict pre-term birth in singletons but that the accuracy of the prediction depends on when (gestational age) the measurements are made. Lindsay and the team looked at 12 studies in which a total 6188 cervical length measurements were performed using ultrasound on 4409 twin pregnancies. What she found was that in twin pregnancies (like singletons), prediction of preterm birth depends on both cervical length and the gestational age at the time of screening. Specifically, when cervical length is less than 30mm, screening at 18 weeks is most predictive for twin birth at 28 weeks.
Later screening after 22 weeks is most predictive of delivery at 28 to 36 weeks.
Therefore, the team recommends that for twins cervical length ultrasound screening should commence from 18 weeks.