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Selection on maternal and neonate size at birth
1Department of Anthropology, University of Michigan, Ann Arbor 48109.
Human Biology
|August 1, 1993
Summary
Neonatal survival is linked to infant birth size and the mother-neonate size ratio. Mothers of surviving infants tend to be smaller relative to their baby, suggesting a balance in maternal and neonatal size selection.
Area of Science:
- Evolutionary biology
- Human reproduction
- Perinatal health
Background:
- Neonatal size is a key determinant of infant survival within the first month of life.
- Maternal characteristics, such as pre-pregnancy weight, height, and age, influence neonatal size.
- Selection pressures may act on traits correlated with birth weight and gestational age.
Purpose of the Study:
- To investigate the operation of natural selection on both neonatal and maternal size using a path-analysis approach.
- To determine the relationship between maternal size, neonatal size, and neonatal survivorship.
Main Methods:
- Utilized path analysis to model the relationships between maternal characteristics, neonatal size, and survival.
- Examined the direct and indirect effects of maternal size on neonatal mortality.
Main Results:
- Neonatal survivorship is dependent on infant birth size.
- A negative allometric relationship exists between neonate size and maternal size; mothers of surviving infants are smaller relative to their neonates.
- Maternal size has no direct effect on neonatal mortality.
Conclusions:
- Selection may maintain a balance between maternal and neonate size.
- The relative size difference between mother and neonate is a critical factor in neonatal survival.