Does every cousin marriage result in a higher-risk pregnancy?
Last reviewed:
Direct answer
No. Most children of first-cousin couples are not born with a major genetic disorder. The relevant finding is a population-level increase in probability, not a certainty for an individual pregnancy. Reviews commonly place the background risk of a major congenital or genetic problem near 2–3% and estimate an additional roughly 2–3 percentage points for first cousins. Risk can be substantially higher when a known condition recurs in the family, both partners carry the same variant, or related marriages have continued across generations.
Sources used
Genetic Counseling and Screening of Consanguineous Couples and Their Offspring
Journal of Genetic Counseling
Practice resource explaining recurrence risk, family history and counseling for related couples.View sourceConsanguinity and reproductive health among Arabs
Reproductive Health, PubMed Central
Peer-reviewed review summarizing the additional absolute risk associated with first-cousin unions.View source