In this study, we used data from a large sample of Rwandan women to describe pregnancy outcomes and to investigate predictors of LBW including mother’s HIV status and/or ART use. Globally, the prevalence of preterm birth varies by country and it is estimated to be about 12% in sub-Saharan Africa (SSA) [41]. Overall, with < 1% of preterm birth and stillbirth, the prevalence of poor pregnancy outcomes was relatively low in our sample irrespective of HIV status. Moreover, about 14% of livebirths in SSA are estimated to be LBW [41, 42]. The 3.5% prevalence of LBW in our sample is also lower than the 6.9% reported in the Rwanda recent national demographic health survey [43]. This may be a result of the fact that all 10 participating HIV clinics were in health centers. In the Rwandan pyramidal health system, only uncomplicated pregnancies and deliveries are handled at the level of the health centers. Women with preterm labor, who are more likely to deliver preterm and LBW are referred to the district hospitals.
Consistent with a recent systematic review [44], WLHIV in our sample have higher prevalence of stillbirths, preterm and LBW infants and mothers with higher body weight and multigravidae status have lower odds of delivering a LBW infant. In a meta-analysis published prior to May 2015, Xia et al [30] found that maternal HIV infection was significantly associated with both LBW and preterm delivery. However, they also found that ART did not significantly change the associations of maternal HIV exposure with LBW and preterm delivery. Although our odds ratio of 1.48 measuring the size of the association of HIV/ART with LBW is slightly lower than the 1.73, reported by Xia et al, its 95% CI overlaps their pooled estimate. The majority of WLHIV (89%) were using ART, but we found that the use of ART reduced the odds of LBW by almost a half. The bivariate association between ART use and LBW was only significant in a sample of all singleton live births, yet this suggests the need to promote ART adherence among pregnant WLHIV. Our findings are consistent with a recent registry study from Malawi. Chamanga et al (45) compared adverse birth outcomes among WLHIV and HIV-uninfected women delivering in high (a referral hospital) and low risk (primary healthcare facilities) settings. They showed that rates of LBW and PTB are significantly higher among WLHIV compared to HIV-uninfected and those differences are more pronounced in high-risk settings than in low-risk PHC facilities. This aligns with this study’s findings that showed that even in a sample of relatively healthier uncomplicated pregnancies delivered in low-risk settings, WLHIV still had higher rates of poor pregnancy outcomes compared to women without HIV.
Among WLHIV, ART use was significantly inversely associated with LBW in bivariable analyses and adjustment for age and primigravidae status did not change the estimate substantially. In the PROMISE study [32], women receiving triple ART, especially TDF-based regimens, had significantly higher rate of LBW that those on zidovudine alone. Our findings of a potentially protective effect of ART might be due to uncontrolled/residual confounding as the reasons why some women were not on ART at the time of delivery despite the indication in ANC registries.
It is well known that maternal nutrition during pregnancy has a pivotal role in the regulation of placental-fetal development, that suboptimal maternal nutrition yields LBW [46–48] and nutritional interventions during pregnancy have been shown to positively affect LBW [49, 50]. Thus, the strong association between maternal underweight and LBW that we observed could serve as evidence to support such interventions particularly for WLHIV and primigravidae women.
Our study has some limitations. As discussed above, our sample may be biased towards healthier pregnancies and thus better pregnancy outcomes due to the systematic referral of any potentially complicated pregnancy/delivery to district hospitals. This in turn may explain the relatively low prevalence of poor pregnancy outcomes in our population despite the large number of women and births. Retrospectively linking datasets from ANC and delivery registries allowed for rich data from a large cohort of women. However, data missingness was high for some key variables and guided our decision to not include key important variables like women’s education, occupation and income. These factors could have affected the socioeconomic and nutritional statuses of women during pregnancy.
Despite these limitations, this study has several strengths. It uses data from a large cohort of women in Rwanda, a country that has implemented Option B + providing lifelong ART to all pregnant WLHIV since 2012 and thus allowing us to revisit the association between exposure to HIV (and ART) during pregnancy and pregnancy outcomes in this era of universal ART. To our knowledge, there have been no studies assessing the association between in utero HIV and/or ART exposure and LBW in Rwanda and only a few similar studies in other sub-Saharan countries [32, 51, 52]. This study fills a gap in the literature and advances understanding of the effects of HIV and/or ART exposure during pregnancy on birth outcomes, and birth weight, which have important implications for infants’ growth, development, morbidity and mortality in the long-term perspective.