Intrauterine growth and infant temperamental difficulties: the Generation R Study

OBJECTIVE: To determine whether intrauterine growth trajectories are associated with temperamental difficulties in infancy. METHOD: The Generation R Study is a population-based cohort study from fetal life onward. Size at different time points during gestation and growth trajectories, calculated on the basis of repeatedly measured fetal growth characteristics, were related to temperamental dimensions, assessed with the Infant Behavior Questionnaire-Revised, in 3,792 infants age 6 months. RESULTS: Birth weight, adjusted for gestational age, was negatively associated with activity level and duration of orienting. These associations disappeared after additional adjustment for maternal height, age, educational level, and national origin. Similarly, the negative associations between intrauterine total body weight gain and falling reactivity and activity level diminished after correction for maternal and child characteristics. After full adjustment, reduced fetal weight gain was only related to prolonged duration of orienting. Children scored 0.38 (95% confidence interval 0.09-0.68) points higher on duration of orienting per SD decrease in total body weight gain from mid-pregnancy to birth. CONCLUSIONS: After controlling for several genetic and socioeconomic status related factors, we found little indication of an association between intrauterine growth trajectories and temperamental difficulties in infants.