Maternal Malaria During Pregnancy and Infant Mortality Rate: Critical Literature Review and a New Analytical Approach

Background & Objectives: Malaria during pregnancy is a recognised risk factor for low birth weight and probably decreases the survival of offspring, particularly during their first month of life. On the other hand, acquired maternal immunity may protect infants against malaria infection or disease. This study assesses these two opposite effects simultaneously.

Methods: We used the data of a large epidemiological study on malaria (Garki project) to analyse the impact of malaria during pregnancy on survival of offspring in their first year of life. The dataset contains 138,197 survey records, representing 12,849 subjects. Of 663 reported deliveries, 417 could be linked to survival data for the newborn.

Results: The mortality rate during the first year of life was independent of maternal malaria infection during pregnancy (crude rate ratio 1.0). After adjustment for malaria in infancy, the rate ratio was 1.2. The corresponding rate ratios for maternal malaria during the second half of pregnancy were 1.46 and 1.73. None of these rate ratios was statistically significant. This may be due to the small number of deaths in the first year of life with a complete record of maternal malaria (27 deaths). The infants during the first four months of life had the lowest risk for Plasmodium falciparum, R malariae and P. ovale infections which may be partly due to acquired maternal immunity. There was a positive association between malaria during pregnancy and malaria during first year of life which might be due to similarity in exposure risks within a family, or confounding effects of socioeconomic status. However, this association was weaker in the first four months of life, and in those women who contracted infection during the second half of pregnancy. This may indicate that acquired immunity is stronger in this group and partially protects babies for a few months.

Interpretation & Conclusion: It seems that on the whole, malaria during pregnancy was not a major risk factor for infant mortality in the Garki project. These results suggest that ignoring acquired maternal immunity may overestimate the hazard of malaria during pregnancy on infant survival.