The cognitive development from childhood to adolescence of low birth weight children born after medical assisted reproduction – a UK longitudinal cohort study
Background: Prior research on the consequences of medical assisted reproduction (MAR) documents an increased risk of poor birth outcomes such as low birth weight (LBW), raising concerns for their longer-term cognitive development. However, parents who undergo MAR to conceive have, on average, advantaged socioeconomic backgrounds, which could compensate for the negative effects of being born LBW. Previous studies have not analyzed whether the negative effects of LBW are attenuated amongst MAR conceived children.
Methods: We draw on the UK Millennium Cohort Study (waves 1-6), which contains a sub-sample of (n=396) MAR conceived children at age 3. The dependent variable measures cognitive ability at around ages 3, 5, 7, 11 and 14. We examine the cognitive development of four groups of children: MAR conceived low birth weight (MAR-LBW); MAR conceived non-low birth weight (MAR-NLBW); naturally conceived low birth weight (NC-LBW); NC children non-low birth weight (NC-NLBW). We estimate two sets of linear regression models: baseline models to examine the unadjusted association between cognitive development and low birth weight by mode of conception; models adjusted by socio-demographic family characteristics.
Results: In the baseline models, MAR-LBW children do not show any difference in cognitive ability relative to NC-NLBW. If any, they show higher cognitive ability scores at age 5 (β = 0.21, 95% CI: 0.009, 0.418). Moreover, MAR-LBW conceived children show higher cognitive scores than NC-LBW children until age 7. When we account for family characteristics differences are largely attenuated.
Conclusions: Despite the high incidence of LBW among MAR children, they do not seem to experience any stunting in their cognitive development compared to naturally conceived children. This finding is likely explained by the fact that, on average, MAR children are born in socioeconomically advantaged families.