Table 4.

Risk of preterm birth, spontaneous preterm birth, and provider-initiated preterm birth between women with and without preeclampsia among 1444 women in the ZAPPS cohort, August 2015 to June 2018

	N	No. events	Risk	Risk difference	95% CI	Risk ratio	95% CI
Crude
PTB*
No preeclampsia	1347	163	12.1	0	..	1	..
Preeclampsia	97	58	59.6	47.5	31.0, 63.9	4.89	3.43, 6.99
Spontaneous PTB
No preeclampsia	1347	129	9.6	0	..	1	..
Preeclampsia	97	13	13.3	3.7	−7.3, 14.6	1.32	0.55, 3.14
Provider-initiated PTB
No preeclampsia	1347	34	2.5	0	..	1	..
Preeclampsia	97	46	46.3	43.8	23.7, 63.9	18.34	8.37, 40.19
Weighted†
PTB
No preeclampsia	1347	164	12.2	0	..	1	..
Preeclampsia	96	58	59.1	46.9	30.0, 63.9	4.84	3.37, 6.95
Spontaneous PTB
No preeclampsia	1347	129	9.6	0	..	1
Preeclampsia	96	13	13.4	3.8	−7.3, 14.9	1.34	0.56, 3.19
Provider-initiated PTB
No preeclampsia	1347	35	2.5	0	..	1
Preeclampsia	96	45	45.7	43.1	22.6, 63.7	17.92	8.13, 39.53

CI, confidence interval; PTB, preterm birth

^*Prior to imputing, there were 712 participants with preeclampsia and 52 without (680 were missing information on preeclampsia). Of those observed to have preeclampsia, there were 28 preterm births (6 spontaneous and 22 provider-initiated), and of those without, there were 79 preterm births (57 spontaneous, 21 provider-initiated, and 1 not classified). Data exclude 3 participants who miscarried and 3 with unknown HIV serostatus at enrollment.

^†Standardized using inverse probability weights to account for confounding by age and gestational age at study entry