Journal of Epidemiology
Online ISSN : 1349-9092
Print ISSN : 0917-5040
ISSN-L : 0917-5040
Statistical Data
Concordance Rates of Birth Defects After Assisted Reproductive Technology Among 17 258 Japanese Twin Pregnancies: A Nationwide Survey, 2004–2009
Syuichi Ooki
Author information
Supplementary material

2013 Volume 23 Issue 1 Pages 63-69


Background: Most twins after assisted reproductive technology (ART) are dizygotic. Analysis of dizygotic twin pairs is useful in assessing familial aggregation in the development of birth defects.
Methods: Using nationwide post-ART data from the Japan Society of Obstetrics and Gynecology, recurrence risk ratios (RRRs)—defined as probandwise concordance rates of birth defects in twins divided by the prevalence of birth defects in the general population—were calculated as indicators of familial aggregation. Birth defects were then reclassified according to the ICD-10 categories corresponding to codes Q00–Q99. From 2004 to 2009, there were 17 258 twin pregnancies.
Results: At least 1 birth defect was noted in 236 twin pairs: 11 concordant and 225 discordant pairs. Regarding major organ systems, high probandwise concordance rates were observed for congenital malformations of eye, ear, face, and neck (11.8%), cleft lip and cleft palate (10.5%), congenital malformations of the nervous system (9.8%), and other congenital malformations of the digestive system (9.5%). High RRRs were observed for congenital malformations of eye, ear, face, and neck (RRR = 233), specifically other congenital malformations of the ear (RRR = 449); congenital malformations of the great arteries (RRR = 235), specifically those of the patent ductus arteriosus (RRR = 530); and for cleft lip and cleft palate (RRR = 208), specifically cleft palate with cleft lip (RRR = 609). The probandwise concordance rate of any birth defect (8.9%) was nearly identical to the approximated recurrence risk of sib-pairs (8.8%), which assumed multifactorial inheritance.
Conclusions: The present findings suggest that familial aggregation is a factor in some birth defects.

Related papers from these authors
© 2012 by the Japan Epidemiological Association
Previous article Next article