Major birth defects and cancer

Both chromosomal and non-chromosomal birth defects are long established risk factors for childhood cancers.12 Particularly for chromosomal defects, the relative risk of cancer in both childhood and adulthood can be strong for specific types, such as the 200 to 600-fold risk of acute megakaryocytic myeloid leukemia in children with trisomy 21.3 For non-chromosomal birth defects, the relative risk of pediatric cancer is lower, so precisely characterizing these associations has been challenging.

Recently, through large scale linkage in the US, researchers cataloged both known and novel associations between birth defects and cancers in childhood.4 However, US data are unsuited to determining whether the risk of cancer in people with birth defects extends into adulthood, both because birth defects registries have existed there for only a few decades and because they cannot account for migration into or out of states.5

The Nordic registries feature information on birth defects as far back as …