Table 3.

Associations between gestational hypertension and pre-eclampsia and preterm birth as revealed by multivariate logistic regression; China, 1993–1996

	Preterm birth
Risk factor	Adjusted RR	95% CI
Age (continuous)	1.04	1.03 to 1.05
Factory worker	1.00	0.96 to 1.05
Other*	0.93	0.87 to 1.00
Unknown occupation	0.40	0.19 to 0.87
Junior high school	1.10	1.02 to 1.18
Primary school or lower	1.22	1.13 to 1.32
Unknown education	1.38	0.95 to 1.99
Folic acid use	0.83	0.80 to 0.86
Gestational hypertension
No	1	—
Yes	1.04	0.98 to 1.11
Pre-eclampsia
No	1	—
Yes	1.39	1.25 to 1.55

*Other includes businessman, teacher, day labourer and civil servant.

RR, risk ratio.