Medicine urgently needs a better understanding of the causes of birth defects, researchers say today.
Dr Marcia Feldkamp of the University of Utah School of Medicine, USA, and colleagues explain that birth defects – "inborn errors of development including structural or functional anomalies with measureable effects on physical, intellectual, and social wellbeing" – represent a large and increasing challenge.
Overall, major birth defects affect one in 33 births, or an estimated 7.9 million babies worldwide.
The team set out to assess the causes of major birth defects in children born in Utah from 2005 to 2009. This covered 5,504 cases among 270,878 births. A definite cause was found in 20.2% of cases, and almost all of these were due to chromosomal or genetic conditions.
Writing in BMJ today (31 May), the team conclude: "These findings underscore the gaps in our knowledge regarding the causes of birth defects."
Many affected babies die, so estimates of the global burden of birth defects underestimate the true burden by at least 25%, they say.
For the causes that are known, such as smoking or diabetes, "assigning causation in individual cases remains challenging", they write, adding: "For the causes that are still unknown, better strategies are needed."
The authors call on researchers to look at aetiology, morphology, and pathogenesis when carrying out epidemiologic studies, and call for greater collaboration between researchers such as developmental biologists, clinicians such as medical geneticists, and epidemiologists.
Novel methods of objectively measuring foetal exposures (rather than maternal self-reports), could also help, they add.
Feldkamp, M. L. et al. Etiology and clinical presentation of birth defects: population based study. BMJ 31 May 2017 doi: 10.1136/bmj.j2249 [abstract]
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