The impact of fertility changes on maternal mortality

Huang, Wei; (2011) The impact of fertility changes on maternal mortality. PhD thesis, London School of Hygiene & Tropical Medicine. DOI: 10.17037/PUBS.00682434

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As less developed countries experience lower fertility, the age/parity distribution of pregnancies may shift. While these shifts may affect maternal mortality levels, their exact impact remains largely unknown. The aim of this thesis is to quantify the impact of fertility changes on maternal mortality. First, the literature was systemically reviewed for the strength of association between maternal age/parity and the maternal mortality ratio. Second, a retrospective cohort study utilised data from Matlab, Bangladesh to investigate the relationship between maternal age/gravidity and the pregnancy-related mortality ratio (PRMRatio) using logistic regressions. Lastly, the impact of observed (in Matlab) and theoretical shifts in childbearing composition on pregnancy-related mortality indicators was modelled using a compartmental model. The systematic review, including 62 studies, found that the risk of maternal death was higher for very young adolescents, older women and nulliparas. However, it was difficult to disentangle the confounding effect of age and parity. The retrospectivec ohort study found that the odds of pregnancy-relatedd eath was four times higher for women at the extreme maternal ages, even after adjustment for confounders, including gravidity. Nulligravidas were at increased risk of pregnancy-related death (adjusted OR=1.63, Cl: 1.24-2.16), but multigravidas were not. The adverse effect of first pregnancies was more pronounced for older women. The compartmental model suggests that the fertility decline in Matlab between 1983-1993 and 2000-2005 accounted for a 30% reduction in the pregnancy-related mortality rate (PRMRate). However, it made no contribution to the reduction in the PRMRatio observed during this period. Reducing or eliminating pregnancies at extreme ages and high gravidity could reduce the PRMRatio by 1-17% and the PRMRate by 1-50%. If all women had a maximum of one pregnancy each, the PRMRate would decrease by 74%. However, the PRMRatio would increase by 32% due to higher risk of first pregnancies. Fertility changes have limited impact on maternal mortality ratios, but can have substantial effect on the maternal mortality rate.

Item Type: Thesis
Thesis Type: Doctoral
Thesis Name: PhD
Contributors: Ronsmans, C (Thesis advisor);
Additional Information:
Faculty and Department: Faculty of Epidemiology and Population Health


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