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 pregnancy	Second pregnancy (No (%) with complication/No (%) at risk)
	Term pre-eclampsia			Term placental abruption			Term stillbirth			Term neonatal death*			Term SGA 2.5‡
	Pre-eclampsia†	Relative risk (95% CI)		Placental abruption†	Relative risk (95% CI)		Stillbirth	Relative risk (95% CI)		Neonatal death	Relative risk (95% CI)		SGA 2.5	Relative risk (95%CI)
Term	3149/246 926 (1.3)	Reference		446/256 942 (0.2)	Reference		341/274 327 (0.1)	Reference		149/273 789 (0.05)	Reference		5467/268 324 (2.0)	Reference
All preterm	349/11 353 (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 weeks	99/2893 (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 weeks	250/8460 (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.