An investigation of the effect of paternal occupation group at conception on birth weight and gestational age. ALSPAC Study Team of Pregnancy and Childhood.

The occupational histories of fathers were collected prospectively as part of the Avon Longitudinal Study of Pregnancy and Childhood (ALSPAC), and were used to investigate the association of paternal job title with a baby's birth weight and gestational age. The analysis cohort consisted of 4,795 singleton live-born babies whose fathers responded fully to questionnaire items regarding occupational history. Jobs were coded using the British Standard Occupational Codes and classified into nine major occupational groups. A 73-gram difference (95% CI: 0.16, 145.17) was found between the mean birth weight of full-term babies born of professional fathers (3,543 gm) and of fathers working in craft and related occupations (3,470 gm). This difference decreased and lost significance after controlling for sociodemographic variables. No difference was found in the mean birth weight of preterm babies, or in the rate of preterm delivery, when analyzed by paternal occupation at conception. Our results suggest that when important sociodemographic variables are known, the father's job title alone may not be a useful predictor of birth weight or preterm delivery.