Neonatal mortality in gestational hypertensive versus non-hypertensive twin pregnancies, U.S. matched multiple birth data 1995–2000.

HR = Hazard ratio; CI = confidence interval.*Hazard ratios adjusted for maternal race, marital status, age, education, parity, smoking, other maternal major illnesses, fetal sex, mode of delivery and twin-cluster level dependence in Cox regression models.**There were a significant number of neonatal deaths with missing birth weights.a The denominators are smaller than those numbers in Table 2 or 4 because neonatal mortality was calculated based on live births only as the denominators, while perinatal mortality and stillbirth rates were calculated based on all births (live births plus stillbirths) as the denominators.t Gestational age group-specific mortality rates and hazard ratios were calculated using the number of foetuses at risk and the number of neonatal deaths in the time interval specified.