Case study

The effect of infertility and its treatment on child health and development

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Author: Claire Carson, University of Oxford, Collaborators include Jenny Kurinczuk and Maggie Redshaw of Oxford, along with Yvonne Kelly and Amanda Sacker of the Institute of Social and Economic Research, University of Essex.This research was part of a larger project led by Maria Quigley, University of Oxford.

Date: 15 September 2011

Type of case study: Research

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."

About the data

The Millennium Cohort Study follows the lives of a sample of nearly 19,000 babies born between 1 September 2000 and 31 August 2001 in England and Wales, and between 22 November 2000 and 11 January 2002 in Scotland and Northern Ireland. The sample design allowed for disproportionate representation of families living in areas of child poverty, in the smaller countries of the UK and in areas with high ethnic minority populations in England. The first survey recorded the circumstances of pregnancy and birth, the early months of life, and social and economic background. This study used the MCS First Survey, 2001-2003, Second Survey, 2003-2005, Third Survey, 2006 and the Survey of Mothers who Received Assisted Fertility Treatment, 2003.

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 and outputs

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.

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