Table 3

Relative risk of term complications in second births after preterm birth in first pregnancy among women without specific complications in first pregnancy (both among term and preterm), Norway 1999-2015

First pregnancySecond pregnancy (No (%) with complication/No (%) at risk)
Term pre-eclampsiaTerm placental abruptionTerm stillbirthTerm neonatal death*Term SGA 2.5‡
Pre-eclampsia†Relative risk (95% CI)Placental abruption†Relative risk (95% CI)StillbirthRelative risk (95% CI)Neonatal deathRelative risk (95% CI)SGA 2.5Relative risk (95%CI)
Term3149/246 926 (1.3)Reference446/256 942 (0.2)Reference341/274 327 (0.1)Reference149/273 789 (0.05)Reference5467/268 324 (2.0)Reference
All preterm349/11 353 (3.1)2.4 (2.2 to 2.7)45/13 416 (0.3)1.9 (1.4 to 2.6)17/13 942 (0.1)0.98 (0.6 to 1.6)(0.07)§1.3 (0.7 to 2.6)551/14 336 (3.8)1.9 (1.7 to 2.1)
20-33 weeks99/2893 (3.4)2.7 (2.2 to 3.3)19/3599 (0.5)3.0 (1.9 to 4.8)(0.2)§1.6 (0.8 to 3.5)(0.2)§4.0 (1.9 to 8.5)206/3961 (5.2)2.6 (2.2 to 2.9)
34-36 weeks250/8460 (3.0)2.3 (2.0 to 2.6)26/9817 (0.3)1.5 (1.03 to 2.3)(0.1)§0.8 (0.4 to 1.4)(0.03)§0.5 (0.2 to 1.7)345/10 375 (3.3)1.6 (1.5 to 1.8)

SGA 2.5=small for gestational age 2.5th centile.

  • * Study period restricted to 1999-2014 (n=258 279).

  • Pregnancies ending in stillbirth (n=358) are excluded from the at risk group for the outcome of neonatal death.

  • To avoid data entry issues in the calculation of SGA centiles, four women with term pregnancies with birth weights <1000 g were excluded in term SGA analyses, and eight women with preterm pregnancies and birth weights ≤100 g were excluded from the preterm SGA analyses.

  • § Cell counts ≤10 are suppressed to protect potentially identifiable rare outcomes.