Background: This is an examination of the characteristics of the women who enrolled into both the ALSPAC cohort during the initial recruitment phase in 1991-1992 and subsequently into the UKBiobank (UKBB) cohort from 2007 to 2010. There is substantial overlap in recruitment across the two cohorts with the existing Avon Longitudinal Study of Parents and Children (ALSPAC) sampling frame being included in that deployed latterly for UKBiobank. Methods: A process was developed using anonymisation and encryption to flag individuals participating in both studies without revealing the identity of those participants. A description of participant characteristics was undertaken to compare the demographic, socio-economic, locational, consent and participatory characteristics of the women in ALSPAC who were also eligible to participate in UKBiobank by their UKBB participation status. Results: The ALSPAC mothers enrolled in UKBB were more engaged in and contributed more data to ALSPAC than those who were eligible to join UKBB but did not enrol. The women in both studies were more likely to be married, have higher levels of education attainment and more financial stability than their counterparts who were only enrolled in ALSPAC. Conclusion: It is possible these characteristics are reflected more generally within UKBB compared to the wider population.