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

HR = Hazard ratio; CI =  confidence interval; SIDS =  sudden infant death syndrome.
*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.
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.