Table 2.
Risk of preterm birth, spontaneous preterm birth, and provider-initiated preterm birth between women with and without HIV among 1444 women in the ZAPPS cohort, August 2015 to June 2018, stratified by preconceptional ART use
| N* | No. events† | Risk | Risk difference | 95% CI | Risk ratio | 95% CI | |
|---|---|---|---|---|---|---|---|
| Crude | |||||||
| PTB | |||||||
| HIV − | 1095 | 151 | 13.8 | 0 | .. | 1 | .. |
| HIV + | 349 | 63 | 18.0 | 4.2 | −0.7, 9.1 | 1.30 | 0.97, 1.74 |
| With preconceptional ART | 227 | 42 | 18.6 | 4.8 | −1.2, 10.7 | 1.34 | 0.95, 1.89 |
| No preconceptional ART | 122 | 20 | 16.9 | 3.1 | −4.6, 10.8 | 1.22 | 0.77, 1.95 |
| Spontaneous PTB | |||||||
| HIV − | 1095 | 95 | 8.7 | 0 | .. | 1 | .. |
| HIV + | 349 | 50 | 14.2 | 5.5 | 1.1, 9.9 | 1.63 | 1.15, 2.32 |
| With preconceptional ART | 227 | 32 | 14.1 | 5.4 | 0.1, 10.7 | 1.62 | 1.07, 2.45 |
| No preconceptional ART | 122 | 17 | 14.3 | 5.6 | −1.5, 12.7 | 1.64 | 0.97, 2.78 |
| Provider-initiated PTB | |||||||
| HIV − | 1095 | 56 | 5.1 | 0 | .. | 1 | .. |
| HIV + | 349 | 13 | 3.8 | −1.3 | −3.9, 1.3 | 0.74 | 0.39, 1.41 |
| With preconceptional ART | 227 | 10 | 4.5 | −0.7 | −3.9, 2.6 | 0.86 | 0.42, 1.77 |
| No preconceptional ART | 122 | 3 | 2.6 | −2.5 | −6.0, 1.0 | 0.49 | 0.13, 1.80 |
| Weighted‡ | |||||||
| PTB | |||||||
| HIV − | 1063 | 148 | 14.0 | 0 | .. | 1 | .. |
| HIV + | 357 | 65 | 18.3 | 4.4 | −1.8, 10.5 | 1.31 | 0.92, 1.86 |
| With preconceptional ART | 230 | 42 | 17.9 | 4.0 | −3.7, 11.6 | 1.28 | 0.82, 1.98 |
| No preconceptional ART | 127 | 24 | 19.0 | 5.1 | −4.4, 14.6 | 1.35 | 0.81, 2.26 |
| Spontaneous PTB | |||||||
| HIV − | 1063 | 92 | 8.7 | 0 | .. | 1 | .. |
| HIV + | 357 | 52 | 14.6 | 5.9 | 0.5, 11.3 | 1.68 | 1.12, 2.52 |
| With preconceptional ART | 230 | 33 | 14.3 | 5.7 | −1.1, 12.5 | 1.65 | 1.00, 2.73 |
| No preconceptional ART | 127 | 19 | 15.0 | 6.3 | −1.7, 14.3 | 1.72 | 0.98, 3.02 |
| Provider-initiated PTB | |||||||
| HIV − | 1063 | 56 | 5.3 | 0 | .. | 1 | .. |
| HIV + | 357 | 13 | 3.7 | −1.6 | −5.0, 1.9 | 0.69 | 0.30, 1.60 |
| With preconceptional ART | 230 | 8 | 3.6 | −1.7 | −5.6, 2.1 | 0.64 | 0.24, 1.70 |
| No preconceptional ART | 127 | 5 | 4.1 | −1.2 | −7.0, 4.6 | 0.72 | 0.18, 2.96 |
CI, confidence interval; PTB, preterm birth; ART, antiretroviral therapy
We observed 1095 HIV− women and 349 HIV+ women, of whom 204 were observed to have preconceptional ART exposure, 99 did not receive preconceptional ART, and 49 were missing information on preconceptional ART. Data exclude 3 participants who miscarried and 3 with unknown HIV serostatus at enrollment.
Among 908 HIV− women with known gestational age at birth, we observed 128 preterm births (of which, 78 were known to be spontaneous, and 46 were provider-initiated, 4 not classified). Among 303 HIV+ women with known gestational age at birth, we observed 53 preterm births (42 spontaneous, 10 provider-initiated, 1 not classified). Among 181 women on preconceptional ART with known gestational age at delivery, there were 33 preterm births (25 spontaneous, 7 provider-initiated, and 1 not classified); among the 85 HIV+ women not on preconceptional ART, there were 14 preterm births (12 spontaneous and 2 provider-initiated).
Standardized using inverse probability weights to account for confounding by age and gestational age at study entry.