Maternal infection with flu-like illness during the 1918 influenza pandemic may have contributed to an increase in premature births and other adverse outcomes, with male infants being hardest hit.
RT’s Three Key Takeaways:
- Maternal Flu in 1918 Tied to Prematurity — Analysis of Swiss birth records shows influenza-like illness during pregnancy, especially in the third trimester, was linked to premature birth, lower birthweight, and higher stillbirth risk.
- Male Infants Hit Hardest — Male babies were more vulnerable, with lower birthweights, greater stillbirth risk from late-pregnancy exposure, and possible miscarriage associations when infection occurred early in gestation.
- Modern Lessons — Findings underscore the importance of protecting pregnant women from influenza through preventive strategies, as pandemics remain a recurring threat.
A modern-day analysis of historical birth records in a Swiss city suggests that maternal infection with flu-like illness during the 1918 influenza pandemic may have contributed to an increase in premature births and other adverse outcomes, with male infants being hardest hit.
The 1918 influenza pandemic was the most severe of the last century, and as influenza pandemics regularly occurred throughout history, they are bound to reoccur in the future.
These findings, published in Annals of Internal Medicine, emphasize the importance of mitigating exposure to influenza during pregnancy through effective preventive measures.
Researchers from the Institute of Evolutionary Medicine at the University of Zurich, Zurich, Switzerland studied 2,177 historical birth records between 1918 to 1920 from University Maternity Hospital of Lausanne to estimate whether in utero exposure to maternal influenza-like illness during the 1918 pandemic was associated with pregnancy outcomes and whether associations varied depending on the trimester of this illness during pregnancy or on fetal sex.
Researchers found that maternal influenza-like illness, particularly during the third trimester, may have triggered premature birth. Birthweight and other anthropometric measures were lowered by maternal influenza-like illness (ILI), especially in the case of third trimester exposure. This outcome disproportionately affected male offspring, as males exposed to ILI during the third trimester had a lower birthweight and a higher risk of stillbirth than exposed females.
Additionally, less males were born to mothers who experienced ILI in the first trimester compared with mothers who were not affected by influenza: this is a hint that ILI early in pregnancy is associated with miscarriage among males. This hypothesis should be further researched with data from various other maternities.
