Table 4. Preterm and term preeclampsia in the second pregnancy according to gestational age and PROM in the first birth, 1998–2012.

(n = 153009).

1st pregnancy		Preterm preeclampsia in 2nd pregnancy						Term preeclampsia in 2nd pregnancy
	Total	n	%	OR	95% CI	OR*	95% CI	n	%	OR	95% CI	OR**	95% CI
Spontaneous term birth	145141	287	0.2	Reference		Reference		1394	1.0	Reference		Reference
Spontaneous non-PROM preterm birth	6172	44	0.7	3.6	(2.6–5.0)	3.3	(2.4–4.5)	110	1.8	1.9	(1.5–2.3)	1.8	(1.5–2.2)
Preterm PROM	1696	11	0.6	3.3	(1.8–6.0)	2.8	(1.5–5.2)	27	1.6	1.7	(1.1–2.4)	1.6	(1.1–2.3)

*Adjusted for the following variables in the 2nd pregnancy: maternal age, chronic hypertension, chronic renal disease, diabetes mellitus, birthweight centile <10 and >90 and inter-birth interval.

**Adjusted for the following variables in the 2nd pregnancy: marital status, chronic hypertension, diabetes mellitus, birthweight centile <10 and >90 and inter-birth interval.

PROM = preterm prelabour rupture of the membranes; OR = odds ratio; CI = confidence interval.