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Article History

Received: 7 February 2025

Accepted: 29 October 2025

First Online: 24 November 2025

Declarations

:

: was granted by the local NHS Research Ethics Committee (28/10/2010 - approval number provided but not published to protect the identity of the study site). This has been previously discussed in detail [ ]. The ethics committee approved the use of ‘passive consent’ where each appointment letter for first maternity clinic during the study period included a Patient Information Sheet(PIS). Midwives were asked to collect an extra ‘study’ blood sample at the time of routine venepuncture ‘as a routine’ without formal consent procedures unless the person spontaneously opted out of the study after reading the PIS. This aspect is discussed at length in the article [ ]. Permission for outcome data, from the 27–30 month Health Visitor developmental assessment held by the health board, to be passed to the safe data facility was given by the Director of Public Health. Ethics approval for linking this data with the maternity booking data was provided by the ethics committee within the safe data facility (03/11/2021).

: We agree to conditions of submission, BioMed Central’s copyright and license agreement and article-processing charge (APC).

: The authors declare no competing interests.