CAMBRIDGE, England, March 2 (UPI) -- A nine-year British study has found being a second-born twin confers a small but increased risk of suffering fatal complications during birth.
For twins born preterm -- before 36 weeks -- there was no difference in overall death rates between the first and second twin. However, this is because the background rate of death is already high for both, due to the effects of prematurity, say researchers at Cambridge University.
However, the researchers found that second twins born at or after the full term of pregnancy -- 36 weeks or longer -- were twice as likely to die during labor or shortly after birth. This excess risk appeared to be due to complications arising from the birth process, according to the study published in the British Medical Journal.
No association appeared between birth order and the overall risk of death among preterm twins. The mother's age and ethnic group also had no discernable impact on twin mortality, the study said.
