New research reveals babies actively combat diseases like Zika before birth, challenging long-held beliefs about fetal vulnerability.

Groundbreaking research reveals fetuses possess a sophisticated immune system that fights infections independently while in the womb. This discovery challenges the long-held belief that unborn babies rely solely on their mother’s immune protection.

Duke-NUS researchers identified specific immune cells in the fetal brain that protect against infections like the Zika virus. The brain’s resident immune cells (microglia) actively defend against pathogens, while other immune cells (monocytes) can help or harm depending on the situation. This dual response system shows remarkable sophistication in fetal immune defense.

Most significantly, researchers found they could enhance protection by targeting specific inflammatory responses. A new experimental drug reduced harmful inflammation in the fetal brain during infections, offering potential new treatments to protect unborn babies. With congenital infections causing approximately 240,000 newborn deaths yearly, this discovery opens new possibilities for protecting babies before birth.

Reference Abdelbasset M, Saron WAA, Ma D, et al. Differential contributions of fetal mononuclear phagocytes to Zika virus neuroinvasion versus neuroprotection during congenital infection. Cell. 2024.