About the research
This study explores the separate effects of pregnancy planning, time to conception and infertility treatment on a range of child health and development outcomes measured at age 3 and 5 years in a national cohort study (the Millennium Cohort Study). Unadjusted test scores at ages 3 and 5 indicate that children born after an unplanned pregnancy are four to five months behind planned children in verbal abilities, while children born after assisted reproduction are three to four months ahead. However, adjusted analyses show that pregnancy planning, sub-fertility, or assisted reproduction do not adversely affect children’s cognitive development at age 3 or 5. The report concludes that these differences observed in the unadjusted analyses are almost entirely explained by marked inequalities in socioeconomic circumstances between the groups. Based on these findings, the authors write that “To help children achieve their full potential, policy makers should continue to target social inequalities.”
Methodology
Data on pregnancy planning, time to conception and infertility treatment were collected in the MCS First Survey. This was used to construct our exposure groups. We also used data on many baseline characteristics from this dataset. The cognitive outcome measures we used were subscales from the British Ability Scales drawn from the MCS Second and Third Survey. The BAS subscales are continuous variables. These were analysed using linear regression, controlling for potential confounding and mediating factors. Our measure of effect was difference in mean score, which was converted into the equivalent difference in months. The data were analysed using survey methods in Stata 11, which allowed us to take into account the stratified, clustered study design of the MCS and use weights for loss to follow up.
Publications
You can read media coverage of this study in the The Telegraph and two peer-reviewed publications:
Carson C., et al. (2011) Effect of pregnancy planning and fertility treatment on cognitive outcomes in children at ages 3 and 5: longitudinal cohort study, BMJ, 26.
Carson C., et al. (2010) Cognitive development following ART: effect of choice of comparison group, confounding and mediating factors, Hum. Reprod. Jan.