ESPE Abstracts

Objective: Low birth weight and prematurity are linked to various behavioural outcomes. In addition, preterm (PT) infants show altered maturation of pituitary–gonadal axis, as demonstrated by its pronounced transient activation during the first postnatal months. Given that gonadal steroid hormones shape the basic processes of neural and behavioural sexual differentiation these elevated sex steroids in premature infants might affect the developing brain and alter subsequent sex-typical behaviour. The objective of this study was to determine whether very low birth weight is associated with differences in sex-typical behaviour in childhood.

Methods: All PT children born with very low birth weight below 1500 g (VLBW), between 1st January 2003 and 31st December 2008 in Kuopio University Hospital, Finland (n=143, mean gestation age, 28.8 weeks), and randomly selected cohorts of PT children with birth weight 1500 g or over (n=282) and FT children (n=454) were included in the study. Sex-typical behaviour was assessed using the 24-item standardized questionnaire, The Pre-school Activities Inventory (PSAI). The final cohort included 449 boys and 430 girls (mean age 4.9 years).

Results: The mean PSAI score was 68.2 (S.D. 10.3) in all boys and 28.4 (S.D. 10.9) in all girls (in t-test P for difference <0.0001). The VLBW boys had less male-typical PSAI scores than other boys (65.7 vs 68.6) and this difference remained significant in the multivariate linear mixed model adjusting for age at assessment, maternal age, exposure to antenatal corticosteroid and number of brothers and sisters (B −3.3, P=0.02). The VLBW girls had significantly less female-typical PSAI scores than other girls (30.8 vs 27.9, B 3.5, and P=0.02).

Conclusion: Very low birth weight is associated with reduced sex-typical behaviour in childhood in both sexes. This finding may reflect differences in the postnatal hormonal milieu of VLBW infants. Further prospective studies are needed to verify these findings and further examine the mechanisms underlying them.