Pregnancy disorders in Africa and the obstetric dilemma

Relative impact of pre-eclampsia on birth weight in a low resource setting: A prospective cohort study

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Pre-eclampsia is the major determinant of birthweight across all gestations in Uganda.

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Pre-eclampsia accounts for ×10 more birthweight variability than all other factors.

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In pre-eclampsia, gestation predicts birthweight better than disease severity.

Objectives

Low birth-weight is a major risk factor for perinatal death in sub-Saharan Africa, but the relative contribution of determinants of birth-weight are difficult to disentangle in low resource settings. We sought to delineate the relationship between birth-weight and maternal pre-eclampsia across gestation in a low-resource obstetric setting.

Study design

Prospective cohort study in a tertiary referral centre in urban Uganda, including 971 pre-eclampsia cases and 1461 control pregnancies between 28 and 42 weeks gestation.

Main outcome measures

Nonlinear modeling of birth-weight versus maternal pre-eclampsia status across gestation. Models were adjusted for maternal-fetal characteristics including maternal age, parity, HIV status, and socio-economic status. Propensity score matching was used to control for the severity of pre-eclampsia at different gestational ages.

Results

Mean birth-weight for pre-eclampsia cases was 2.48 kg (±0.81SD) compared to 3.06 kg (±0.46SD) for controls (p < 0.001). At 28 weeks, the mean birth-weight difference between pre-eclampsia cases and controls was 0.58 kg (p < 0.05), narrowing to 0.17 kg at 39 weeks (p < 0.01). Controlling for pre-eclampsia severity only partially explained this gestational difference in mean birth-weight between pre-eclampsia cases and controls. Holding gestational age constant, pre-eclampsia status predicted 7.1–10.5% of total variation in birth-weight, compared to 0.05–0.7% for all other maternal-fetal characteristics combined.

Conclusions

Pre-eclampsia is the dominant predictor of birth-weight in low-resource settings and hence likely to heavily influence perinatal survival. The impact of pre-eclampsia on birth-weight is smaller with advancing gestational age, a difference that is not fully explained by controlling for pre-eclampsia severity.

Immune Regulation in Eutherian Pregnancy: Live Birth Coevolved with Novel Immune Genes and Gene Regulation

Novel regulatory elements that enabled expression of pre-existing immune genes in reproductive tissues and novel immune genes with pregnancy-specific roles in eutherians have shaped the evolution of mammalian pregnancy by facilitating the emergence of novel mechanisms for immune regulation over its course. Trade-offs arising from conflicting fitness effects on reproduction and host defenses have further influenced the patterns of genetic variation of these genes. These three mechanisms (novel regulatory elements, novel immune genes, and trade-offs) played a pivotal role in refining the regulation of maternal immune systems during pregnancy in eutherians, likely facilitating the establishment of prolonged direct maternal-fetal contact in eutherians without causing immunological rejection of the genetically distinct fetus.