Mortality, morbidity and educational outcomes in children of consanguineous parents in the Born in Bradford cohort.

Background: Children of consanguineous parents have a higher risk of infant and childhood mortality, morbidity and intellectual and developmental disability.

Methods: Using a UK based longitudinal cohort study we quantify differences according to the consanguinity status of children from birth to 10 in mortality, health care usage, two health and three educational outcomes. The cohort comprises 13727 children; 35.7% White British, 43.7% Pakistani heritage, and 20.8% are from other ethnic groups.

Results: Compared to children whose parents were not related children whose parents were first cousins were more likely to die by age 10 (odds ratio 2.81, 95% CI 1.82-4.35) to have higher rates of primary care appointments (incident rate ratio 1.39, 95% CI 1.34-1.45) and more prescriptions (incident rate ratio 1.61, 95% CI 1.50-1.73). Rates of hospital accident and emergency attendance (incident rate ratio 1.21,95% CI 1.12-1.30) and hospital outpatients' appointments (incident rate ratio 2.21,95% CI 1.90-2.56) are higher. Children of first cousins have higher rates of speech/ language development difficulties (odds ratio 1.63, 95% CI 1.36-1.96) and learning difficulties (odds ratio 1.89, 95% CI 1.28-2.81). When they begin school they are less likely to reach phonics standards (odds ratio 0.73, 95% CI 0.63-0.84) and less likely to show a good level of development (odds ratio 0.61, 95% CI 0.54-0.68). At age 10 there are higher numbers with special educational needs from first cousin unions compared to all children whose parents are not blood relations (odds ratio 1.38, 95% CI 1.20-1.58). Effect sizes for consanguinity status are similar in univariable and multivariable models where a range of control variables are added.

Conclusions: There is higher childhood mortality and greater use of health care as well as higher rates of learning difficulties, speech and language development challenges and substantive differences in education outcomes in children whose parents are first cousins.