Table 4.

Risk factors for HIV seroconversion in women in the reproductive age group, South Africa, 2010–2015

	aUnadjusted hazard ratio estimates			bAdjusted hazard ratio estimates
Effect	Point estimate	95% CI	P value	Point estimate	95% CI	P value
Pregnancy
Not pregnant	Ref	-	-	Ref	-	-
Pregnant	1.1	0.8–1.5	0.420	0.4	0.2–0.9	0.032
Postpartum	1.1	0.6–1.9	0.871	1.2	0.4–3.2	0.744
Age
25–49 years	Ref	-	-	Ref	-	-
15–24 years	2.4	2.0–2.8	< 0.001	2.5	2.1–3.1	< 0.001
Gravidity
No pregnancies	Ref	-	-	Ref
One pregnancy	1.4	1.1–1.9	0.006	1.5	1.1–1.9	0.004
Two or more pregnancies	1.0	0.8–1.2	0.789	1.7	1.3–2.2	< 0.001
Number of live born infants at delivery	1.02	1.0–1.03	0.004	1.02	1.0–1.03	0.033
Area of residence
Peri-urban	Ref	-	-	Ref	-	-
Urban	0.8	0.7–1.0	0.046	0.98	0.8–1.2	0.870
Rural	0.94	0.6–1.5	0.819	1.0	0.6–1.6	0.994
Education level
Less than one year	Ref	-	-	Ref	-	-
At least primary education	1.9	1.0–3.7	0.065	1.7	0.9–3.4	0.122
At least secondary education	3.2	1.7–5.9	< 0.001	2.0	1.1–3.8	0.035
Unknown	4.2	2.2–8.1	< 0.001	3.2	1.7–6.3	0.001
Distance to nearest level 1 road, km	1.0	1.003–1.009	0.063	0.98	0.97–1.0	0.089
Knows HIV status
Yes	Ref	-	-	Ref	-	-
No	0.9	0.7–1.1	0.364	0.94	0.8–1.2	0.601
Refused	1.3	0.9–1.8	0.125	1.5	1.0–2.0	0.025
Age and pregnancy
Not pregnant, 25–49 years	Ref	-	-	Ref	-	-
Pregnant; 15–24 years	2.6	1.1–6.1	0.032	2.3	1.0–5.5	0.056
Postpartum, 15–24 years	0.6	0.2–2.2	0.483	0.58	0.2–2.0	0.389

^aResidency type, distance from level 1 clinic and nearest school, have heard about ART, pregnancy order, and pregnancy outcome were not included in the final multivariable model as P > 0.2 in the univariable analysis

^bAdjusted for all listed covariates, gravidity including the most recent pregnancy