Malaria antibody responses measured at delivery have been associated with protection from maternal anaemia and low birth weight deliveries. Whether malarial antibodies present in the first half of pregnancy may protect from these or other poor birth outcomes is unclear. To determine whether malaria antibodies in the first half of pregnancy predict pregnancy outcomes, antibodies were measured to a range of merozoite antigens and to antigens expressed on the surface of parasitized red blood cells (pRBCs) in plasma samples collected at 14-20 weeks of gestation from Malawian women. The latter antibodies were measured as total IgG to pRBCs, and antibodies promoting opsonic phagocytosis of pRBCs. Associations between antibodies and maternal haemoglobin in late pregnancy or newborn size were investigated, after adjusting for potential covariates.
Antibodies to pRBC surface antigens were associated with higher haemoglobin concentration at 36 weeks. Total IgG to pRBCs was associated with 0.4 g/l [(95% confidence interval (0.04, 0.8)] increase in haemoglobin, and opsonizing antibody with 0.5 (0.05, 0.9) increase in haemoglobin for each 10% increase in antibody. These antibodies were not associated with birthweight, placental malaria, or newborn anthropometrics. Antibodies to merozoite antigens and non-placental-binding IEs were not associated with decreased risk of any of these outcomes. In some instances, they were negatively associated with outcomes of interest.
Antibodies to placental-binding infected erythrocytes may be associated with higher haemoglobin levels in pregnancy, whereas antibodies to other malaria antigens may instead be markers of malaria exposure. Trial registration clinicaltrials.gov NCT01239693. Registered Nov 10, 2010.
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This publication is based on research funded in part by a grant from the Office
of Health, Infectious Diseases, and Nutrition, Bureau for Global Health, U.S.
Agency for International Development (USAID) under terms of Cooperative
Agreement No. AID-OAA-A-12-00005, through the Food and Nutrition Technical
Assistance III Project (FANTA), managed by FHI 360. Additional funding
was obtained from a grant to the University of California, Davis from the Bill &
Melinda Gates Foundation and the Academy of Finland. SJR is supported by
the National Health and Medical Research Council (NHMRC) of Australia. JGB
supported by a Senior Research Fellowship by the NHMRC of Australia. The
Burnet Institute is supported by the NHMRC IRIIS Scheme and Victorian State
Government Operational Infrastructure Support.