London: Twins should be delivered at the 37th week of a mother's pregnancy period to reduce the risk of stillbirths and newborn deaths, say researchers led by an Indian-origin scientist. Twin pregnancies are high risk with a 13-fold increase in rates of stillbirth in monochorionic twins (twins that share the same placenta), and a five-fold increase in dichorionic twins (twins with separate placenta), compared with singleton pregnancies, the study said. In dichorionic pregnancies, the risk of stillbirths and neonatal death were balanced until 37 weeks' gestation. However, delay in delivery by a week (to 38 weeks) led to an additional 8.8 deaths per 1,000 due to an increase in stillbirth. In monochorionic pregnancies, the risk of stillbirth appears to be higher than neonatal death beyond 36 weeks' gestation. In addition, rates of neonatal morbidity, including respiratory distress syndrome, septicaemia, or neonatal seizures, and admission to the neonatal intensive care unit showed a consistent reduction with increasing gestational age in both monochorionic and dichorionic pregnancies, the researchers said. "We know that women with twin pregnancies have a higher risk of stillbirth compared to women with singleton pregnancies, and this risk gets higher the later they are in pregnancy," said Shakila Thangaratinam, Professor at the Queen Mary University of London (QMUL). "However, earlier delivery can put the babies at risk of problems associated with being born prematurely including neonatal death," Thangaratinam added. The team analysed 35,171 twin pregnancies (29,685 dichorionic and 5,486 monochorionic) to identify the ideal delivery period in an attempt to reduce rates of stillbirth. In the case of pregnancies without complications, women with dichorionic twins should be offered delivery after 37 weeks. Women with monochorionic twins should not be offered delivery before 36 weeks, the researchers suggested "There is a global drive to prevent stillbirths and we know that twin pregnancies are a major risk factor for stillbirths in high income countries," Thangaratinam said. "We hope that this research will help to complement national and international efforts to reduce the rates of stillbirth and unexpected neonatal complications in babies from women with twin pregnancies and will be useful to national guideline and hospital policy makers," Thangaratinam noted, in the paper published in the British Medical Journal.