Paternal and maternal birthweights and the risk of infant preterm birth.

Abstract

Increasing paternal birthweight has been associated with increased risk of fathering a preterm infant, causing speculation that a fetus programmed to grow rapidly can trigger preterm labor. Pregnancies occurring from 1974-1989 among women themselves born in the Danish Perinatal Study (1959-1961) were identified through the Population Register; obstetric records were abstracted. Paternal birthweight was obtained by linking Personal Identification Numbers of the fathers to archived midwifery records. Paternal birthweight was not associated with preterm infants overall. However, there was a significant interaction between paternal and maternal birthweights (P = .003). When the mother weighed less than 3 kg at birth, increasing paternal birthweight was associated with increased occurrence of preterm birth (P for trend = .02); paternal birthweight was unassociated with preterm birth for mothers weighing 3 kg or more at birth (P = .34). When the mother was born small, increasing paternal birthweight was associated with increased risk of preterm birth, suggesting that a fetus growing faster than its mother can accommodate might trigger preterm birth.