Table 3. Univariate and multiple analysis of factors associated with pregnancy incidence. Rio de Janeiro, Brazil, 1996-2016.
| Women characteristics | Univariate analysis | Multiple analysis * | ||
|---|---|---|---|---|
| HR (95%CI) | p-value | HR (95%CI) | p-value | |
| Follow-up period | ||||
| 1996-2000 | 1.00 | |||
| 2001-2005 | 0.79 (0.49; 1.28) | 0.34 | 1.17 (0.68; 2.00) | 0.57 |
| 2006-2010 | 0.58 (0.37; 0.91) | 0.02 | 0.74 (0.40; 1.37) | 0.34 |
| 2011-2016 | 0.59 (0.37; 0.94) | 0.03 | 0.55 (0.29; 1.07) | 0.08 |
| Age (years) | ||||
| < 20 | 1.00 | |||
| 20-34 | 0.45 (0.2; 1.0) | 0.05 | 0.63 (0.27; 1.50) | 0.30 |
| ≥ 35 | 0.12 (0.05; 0.28) | < 0.01 | 0.22 (0.08; 0.56) | < 0.01 |
| Race/Ethnicity | ||||
| White | 1.00 | |||
| Black | 0.94 (0.62; 1.44) | 0.79 | ||
| Mixed | 0.72 (0.50; 1.03) | 0.07 | ||
| Missing | 0.95 (0.22; 4.16) | 0.95 | ||
| Schooling years | ||||
| ≤ 8 | 1.00 | |||
| > 8 | 0.92 (0.66; 1.27) | 0.60 | ||
| Missing | 0.98 (0.13; 7.18) | 0.98 | ||
| Smoking | ||||
| No | 1.00 | |||
| Yes | 1.05 (0.72; 1.53) | 0.80 | ||
| Alcohol use | ||||
| No | 1.00 | |||
| Yes | 0.96 (0.70; 1.31) | 0.79 | ||
| Missing | 0.96 (0.21; 4.45) | 0.96 | ||
| Drug use | ||||
| No | 1.00 | |||
| Yes | 1.35 (0.86; 2.13) | 0.19 | ||
| Missing | 0.74 (0.20; 2.72) | 0.65 | ||
| Domestic violence | ||||
| No | 1.00 | |||
| Yes | 0.83 (0.58; 1.19) | 0.32 | ||
| Missing | 0.33 (0.04; 2.54) | 0.28 | ||
| Sexual violence | ||||
| No | 1.00 | |||
| Yes | 1.13 (0.73; 1.75) | 0.57 | ||
| Missing | 1.21 (0.27; 5.42) | 0.81 | ||
| Pregnancy in adolescence | ||||
| No | 1.00 | 1.00 | ||
| Yes | 1.73 (1.17; 2.56) | 0.01 | 1.65 (1.12; 2.44) | 0.01 |
| Missing | 1.1 (0.53; 2.30) | 0.80 | 0.57 (0.25; 1.28) | 0.17 |
| Age at first sexual intercourse (years) | ||||
| < 15 | 1.00 | |||
| 15-19 | 0.65 (0.45; 0.92) | 0.02 | ||
| ≥ 20 | 0.14 (0.06; 0.30) | < 0.01 | ||
| Missing | 0.4 (0.14; 1.20) | 0.10 | ||
| Marital status | ||||
| Does not live with a partner | 1.00 | |||
| Live with a partner | 1.55 (1.12; 2.14) | 0.01 | ||
| Number of children | ||||
| Median (IQR) | 0.83 (0.68; 1.03) | 0.09 | ||
| 0 | 1.00 | |||
| 1 | 0.64 (0.41; 1.02) | 0.06 | 0.55 (0.36; 0.84) | 0.01 |
| ≥ 2 | 0.48 (0.27; 0.83) | 0.01 | 0.43 (0.26; 0.71) | < 0.01 |
| Contraceptive method | ||||
| Low efficacy ** | 1.00 | 1.00 | ||
| Hormonal or IUD | 0.24 (0.08; 0.72) | 0.01 | 0.27 (0.10; 0.78) | 0.02 |
| Dual (hormonal or IDU + barrier) | 0.53 (0.37; 0.76) | < 0.01 | 0.63 (0.41; 0.99) | 0.04 |
| Missing | 0.54 (0.33; 0.86) | 0.01 | 0.62 (0.38; 1.02) | 0.06 |
| Time since HIV infection diagnosis (years) | ||||
| < 2 | 1.00 | |||
| 2-4 | 1.09 (0.71; 1.66) | 0.70 | ||
| ≥ 5 | 0.94 (0.57; 1.56) | 0.81 | ||
| Missing | 3.02 (1.61; 5.66) | < 0.01 | ||
| Diagnosis of opportunistic disease | ||||
| No | 1.00 | |||
| Yes | 0.85 (0.58; 1.24) | 0.40 | ||
| HIV-1 RNA (copies/mL) | ||||
| < 50 | 1.00 | 1.00 | ||
| ≥ 50 | 0.91 (0.67; 1.24) | 0.55 | 0.57 (0.39; 0.85) | 0.01 |
| Missing | 2.01 (0.87; 4.67) | 0.10 | 0.91 (0.33; 2.55) | 0.86 |
| CD4+ T lymphocyte count nadir (cells/mm³) | ||||
| Median (IQR) | 1.01 (1.01; 1.02) | < 0.01 | ||
| < 200 | 1.00 | 1.00 | ||
| 200-349 | 1.3 (0.90; 1.88) | 0.17 | 1.19 (0.82; 1.73) | 0.36 |
| 350-499 | 1.84 (1.17; 2.90) | 0.01 | 2.58 (1.58; 4.23) | < 0.01 |
| ≥ 500 | 2 (1.18; 3.38) | 0.01 | 2.78 (1.57; 4.90) | < 0.01 |
| ARV use | ||||
| No use | 1.00 | 1.00 | ||
| HAART with Efavirenz | 0.13 (0.05; 0.34) | < 0.01 | 0.19 (0.07; 0.51) | < 0.01 |
| HAART without Efavirenz | 2.18 (1.36; 3.51) | < 0.01 | 3.39 (2.01; 5.73) | < 0.01 |
| No HAART | 2.1 (1.12; 3.91) | 0.02 | 1.69 (0.78; 3.67) | 0.19 |
95%CI: 95% confidence interval; ART: antiretroviral; HAART: highly active antiretroviral therapy; HR: harzard ratio.
* Variables that showed statistical significance in the univariate analysis (p < 0.10) and those clinically relevant were included in the multiple analyses. After backwards selection, variables that were statistically significant at the 5% level were included in the final model;
** Natural, male condom, female condom, diaphragm, withdrawal.