Transplacental transfer of anti-malarial antibodies: a systematic review

Pregnant women and young children bear the highest burden of malaria morbidity/mortality. While transplacental transfer of malaria antibodies protects the child, the efficiency varies by antigen and maternal factors. This systematic review assessed transplacental transfer of malaria antibodies, factors associated with reduced transfer and identified knowledge gaps for future research.

We searched PubMed, Scopus, Web of Science and HINARI from the inception of databases until January 2025. We included published articles reporting anti-malaria antibodies in the mother and newborn, placental transfer and factors associated with reduced transplacental transfer of antibodies against malaria antigen. Two independent reviewers conducted the selection of articles, data extraction and risk of bias assessment. Meta-analyses of malaria prevalence were performed on the peripheral blood of mothers, on the placenta, and on the cord blood of newborns.

Forty-two studies (n=8687 pregnant women and newborns) were included in the analysis. Twelve studies reported the prevalence of malaria among mothers detected peripherally, 13 for placental malaria, and five studies for newborns. The pooled prevalence of peripheral and placental malaria was found to be 31.27% (95%CI: 24.9, 38.45), and 30.65% (95%CI: 20.29, 43.43), respectively. The pooled prevalence of malaria in the newborn was 9.53% (95%CI: 4.18, 20.29). IgG1 and IgG3 against malaria antigen were the predominant IgG that placentally transferred efficiently. IgG against circumsporozoite protein was more transferred to the newborn than those against the merozoite surface protein 3. Factors such as HIV infection, placental malaria, hypergammaglobulinemia in mothers, low birth weight, and primigravida were associated with reduced maternal transfer of antibodies against malaria antigen to newborns.

Maternal transfer of antibodies against malaria antigen to newborns was IgG subclass and antigen-dependent. Vaccination strategies promoting high potential of transplacental transfer in pregnant women may enhance child protection against severe malaria.

https://www.crd.york.ac.uk/PROSPERO/view/CRD42024609217, identifier CRD42024609217.