Environmental factors associated with microcephaly in Africa: A systematic review

Microcephaly, a condition characterized by a head circumference below the mean for age and sex, is a significant indicator of impaired fetal brain development. While some environmental factors have been associated with the development of microcephaly in Africa, the available information remains disjointed, making it difficult for healthcare providers and policy makers to translate the information to preventive measures in maternal and child health. This systematic review aims to synthesize primary studies on environmental determinants of microcephaly, focusing on African populations.

A systematic literature search was conducted using PubMed, Scopus, AJOL, and Wiley Online Library to identify studies published between 2000 and 2025, focusing on environmental exposures and microcephaly in neonates and infants. Observational and interventional studies in English were included, following PRISMA 2020 guidelines. Data were extracted and tabulated by country, exposure type, study design, and reported outcomes.

Sixteen African studies found a multifactorial relationship between environmental exposures and microcephaly. Zika virus infection was a consistent contributor, with maternal febrile illnesses, inadequate antenatal care, HIV exposure, and heavy metal toxicity also linked. Pesticide exposure, particularly to organophosphates and DDT, was associated with neurodevelopmental delays and restricted cranial growth. Ambient air pollution was negatively correlated with neonatal head circumference. Socioeconomic vulnerabilities intensified these environmental risks, especially during epidemic crises like Zika virus outbreaks.

Microcephaly in African populations is a multifactorial issue, influenced by emerging infections like ZIKV, chronic environmental exposures, and healthcare gaps. It calls for integrated public health strategies, including surveillance, early prenatal screening, environmental regulation, and region-specific diagnostic standards. Global evidence supports shared biological vulnerability in low-resource settings.