Risk for birth defects among premature infants: A population-based study

Objective: To investigate the relationship between prematurity and birth de fects. Study design: In a population-based cohort study, infants with birth defect s were ascertained through the Metropolitan Atlanta Congenital Defects prog ram, a surveillance system with active methods of ascertainment. Gestationa l age data were obtained from birth certificates of liveborn, singleton inf ants with and without birth defects born in the 5-county metropolitan Atlan ta area. Results: Among 264,392 infants with known gestational ages born between 198 9 and 1995, 7738 were identified as having birth defects (2.93%). Premature infants (<37 weeks' gestation) were more than two times as likely to have birth defects than term infants (37-41 weeks) (risk ratio = 2.43; 95% CI 2. 30-2.56). This relationship was evident for several categories of birth def ects. The rate of birth defects varied by gestational age categories, with the highest risk in the 29- to 32-week gestational age category (risk ratio = 3.37). Conclusions: The risk for birth defects is increased in premature infants. Awareness of this relationship is important for clinicians caring for prema ture infants. The morbidity and mortality associated with a particular defe ct may be significantly altered by the presence of prematurity. Further stu dy of this association may provide insight into the etiology of these relat ively common problems.