Determinants of Early Neonatal Weight Loss in Historical Swiss Maternity Hospital Records.

OBJECTIVE

Early neonatal weight loss is an aspect of neonatal adaptation influenced by maternal, nutritional, and perinatal factors. Determinants of early neonatal weight loss in historical populations remain poorly understood. This study investigated determinants of neonatal weight loss as an early postnatal adaptation phenotype using Swiss maternity hospital records from 1905 to 1924, including the influence of the First World War and the 1918-1920 influenza pandemic.

METHODS

Birth records from Lausanne Maternity Hospital (1905-1924) were analyzed. Maximum percentage neonatal weight loss was calculated during hospitalization, excluding implausible trajectories (> 20% loss) and weight gains. Associations with feeding type, historical exposures, and maternal health were assessed using multivariable linear and logistic regression for maximum and high (> 10%) weight loss, respectively. Stratified and sensitivity analyses assessed effect heterogeneity and model robustness.

RESULTS

The analytical sample included 11 739 singleton live births. Mean maximum observed neonatal weight loss was 6.7% (SD 3.5%), and 16.8% experienced high weight loss. Compared with artificial feeding, breastfeeding was associated with lower maximum weight loss (β = -1.07 percentage points, 95% CI -1.32 to -0.81) and lower odds of high weight loss (OR = 0.56, 95% CI 0.47-0.68). Mixed feeding was associated with greater weight loss and higher odds of high weight loss. Pandemic exposure was associated with slightly greater weight loss, whereas the association with First World War exposure was small and did not provide clear evidence of an independent association.

CONCLUSION

Feeding mode was the strongest determinant of early neonatal weight loss. Breastfeeding was consistently associated with lower weight loss, while pandemic exposure and maternal influenza during pregnancy were associated with slightly higher weight loss. These findings suggest that neonatal weight loss may provide an early postnatal indicator of neonatal adaptation reflecting both immediate nutritional influences and broader prenatal conditions.