Incidence of Pregnancy after Initiation of Antiretroviral Therapy in South Africa: A Retrospective Clinical Cohort Analysis

Table 2

Incident rate and adjusted incident rate ratio for association of demographic, clinical, and laboratory indicators with incident pregnancy among antiretroviral therapy-naïve 18–45-year-old women initiating HAART in Johannesburg.

Demographics	Incidence rate, crude, per 100 person-years	Rate ratio, adjusted (95% confidence limits)
Current age (years)
18–24.9	10.4 (8.2, 13.2)	13.21 (8.41, 20.75)
25–29.9	9.1 (8.0, 10.4)	10.81 (7.26, 16.09)
30–34.9	7.0 (6.2, 7.8)	7.93 (5.37, 11.70)
35–39.9	3.6 (3.0, 4.2)	4.01 (2.69, 5.99)
40–45.0	0.9 (0.6, 1.3)	1
Baseline pregnancy
Pregnant	6.2 (5.1, 7.7)	0.80 (0.63, 1.03)
Not pregnant	5.0 (4.7, 5.5)	1
Clinical (all time-updated)
HAART regimen
Includes EFV	4.7 (4.3, 5.2)	1
Includes LPVr	5.6 (4.7, 6.7)	1.01 (0.82, 1.26)
Includes NVP	8.2 (6.7, 9.9)	1.19 (0.94, 1.50)
Body mass index (kg/m^2)
<18.5	3.7 (2.6, 5.2)	1
18.5–24.9	5.2 (4.7, 5.8)	1.04 (0.71, 1.53)
25.0–29.9	5.5 (4.8, 6.2)	1.16 (0.78, 1.72)
≥30	5.2 (4.3, 6.2)	1.19 (0.79, 1.80)
Laboratory (all time updated)
Hemoglobin^‡
Normal	5.3 (4.9, 5.8)	1
Low	4.5 (3.7, 5.3)	0.96 (0.76, 1.20)
CD4 count (cells/mm^3)
≤50	2.1 (1.3, 3.3)	0.33 (0.15, 0.75)
51–100	3.2 (2.2, 4.7)	0.68 (0.42, 1.10)
101–200	5.4 (4.5, 6.3)	0.96 (0.77, 1.20)
201–350	5.5 (4.8, 6.3)	1
351–500	6.1 (5.3, 7.1)
>500	5.0 (4.2, 5.9)
Viral load (copies/mL)
≤400	5.5 (5.0, 5.9)	1
401–10,000	5.1 (3.6, 7.3)	0.86 (0.59, 1.25)
>10,000	4.0 (2.8, 5.7)	0.88 (0.60, 1.29)
Adherence
0–79%	3.7 (2.7, 5.3)	0.67 (0.45, 1.01)
80%–94%	5.9 (5.2, 6.8)	1.13 (0.95, 1.34)
≥95%	5.0 (4.5, 5.5)	1

^‡After adjustment for altitude, lower limit of normal hemoglobin is 11.35 g/dL for non-pregnant women.