Identifying families most likely to have missing paternal details in birth registrations using linked data

The purpose of this study was to determine the extent of missing paternal data in birth registrations and the characteristics of families most likely to have missing data. We used a retrospective cohort of children born in Western Australia between 1980 and 2005. Results revealed that the characteristics of families associated with missing paternal information included: living in areas of high socio-economic disadvantage; young single mothers; children and mothers of Aboriginal origin; smoking during pregnancy; preterm birth; and low birth weight. We found that the strong association between adverse child health outcomes and the absence of paternal information might be a source of bias in existing data. This bias may be introduced during the analysis of data because records are often excluded due to missing information. Excluding this data could lead to families at highest risk of adverse outcomes being removed from the sample and subsequently introducing bias. Consideration should be given to the collection of paternal details by midwives to aid in the monitoring and evaluation of birth outcomes of at risk mothers.