To compare the prevalence of small intestinal atresia among twins and singletons in the United States.
The McDonnell Douglas Health Information System (MDHIS), a national registry of newborn diagnoses, 1982 through 1988; and the Metropolitan Atlanta Congenital Defects Program (MACDP), a registry of defects among infants in Atlanta, 1968 through 1989.
Live-born infants with small intestinal atresia.
In both systems, the rate of small intestinal atresia was higher among twins than singletons (MDHIS: 5.5 per 10 000 vs 2.0, relative risk [RR] = 2.8, 95% confidence interval [CI] = 1.9 to 4.0; MACDP: 7.3 vs 2.5, RR = 2.9, 95% CI = 1.5 to 5.7). The increase was more notable among same-sex twins than opposite-sex twins, suggesting an increase among monozygotic twins. It was also more notable among twins with jejunoileal atresia than those with duodenal atresia, suggesting a vascular cause in many cases.
Twins have a higher rate of small intestinal atresia than singletons, possibly due to vascular disruption in monozygotic twins.(Arch Pediatr Adolesc Med. 1994;148:733-739)