Funding for this research was provided by:
Medical Research Council (MM_UU_12013/6)
Received: 15 November 2017
Accepted: 4 April 2018
First Online: 12 April 2018
Ethics approval and consent to participate
: Ethical approval for the study was obtained from the ALSPAC Ethics and Law Committee and the Local Research Ethics Committees (ExternalRef removed). Written informed consent was obtained from the child’s mother on behalf of the mother and child.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.