Fetal deaths with birth defects among Japanese multiples, 1974

The concordance rate of non-chromosomal congenital malformations in twins based on zygosity: a retrospective cohort study

OBJECTIVE

To examine the concordance rate of non-chromosomal congenital malformations in twin pairs based on zygosity.

DESIGN

Retrospective cohort study.

SETTING

A tertiary hospital in Korea.

POPULATION

Twin pairs born at Seoul National University Hospital between 2001 and 2019.

METHODS

Congenital malformations were diagnosed by postnatal workups of neonates or autopsy in cases of stillborn infants. Zygosity was confirmed by sex, chorionicity and DNA analysis.

MAIN OUTCOME MEASURES

Concordance rate of congenital malformations in twin pairs based on zygosity.

RESULTS

In total, 3386 twin pairs were included. The risk of a congenital malformation in the index twin increased significantly if the co-twin had the congenital malformation, and the concordance rate was higher in monozygotic (MZ) than in dizygotic (DZ) twins (37.04 versus 16.77, P < 0.001). An increased risk of a congenital malformation in the presence of the same congenital malformation in the co-twin was observed only for malformations of the nervous system, eye/ear/face/neck, circulatory system, cleft lip/palate, genital organs, urinary system and musculoskeletal system. Significantly higher concordance rates in MZ than in DZ twin pairs were observed only for the nervous system (40.00 versus 0.00, P < 0.001), circulatory system (32.97 versus 19.74, P = 0.021), cleft lip/palate (44.44 versus 0.00, P = 0.017) and urinary system (22.22 versus 0.00, P = 0.004), whereas significant differences were not found for the genital organs or musculoskeletal system.

CONCLUSIONS

Monozygotic twins had higher concordance rates than DZ twins only in specific organ systems. It may be speculated that nervous system, circulatory system, cleft lip/palate and urinary system are primarily genetically affected.

TWEETABLE ABSTRACT

Monozygotic twins had higher concordance rates than dizygotic twins only in specific organ systems.

Concordance rates of birth defects after assisted reproductive technology among 17 258 Japanese twin pregnancies: a nationwide survey, 2004-2009

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.

Increased risk of birth defects among children from multiple births

BACKGROUND

Multiple births are increasing, and may be associated with birth defects.

METHODS

To explore this relationship, data from the Virginia birth defects registry (VaCARES) was analyzed.

RESULTS

During 1989-1998, a total of 44505 children from singleton births and 2258 children from multiple births were born with birth defects in Virginia. The risk of birth defects was significantly increased in children from multiple births as compared to singleton births (birth defect rate per 10000 live births: singleton 482.3, twin 922.0, triplet 1300.0, and quadruplet or higher 2222.2). Increased risk was observed for 39 of 86 diagnoses. The five diagnoses with the highest risk ratio per 10000 live births (RR) were: neurofibromatosis (RR, 12.80), retrolental fibroplasia (RR, 9.96), microphthalmos (RR, 5.24), pulmonary valve anomalies (RR, 5.00), and patent ductus arteriosus (RR, 4.68). A significantly reduced risk ratio for congenital hip dislocation was found in these children (RR, 0.54). In most multiple births, only one child was born with birth defects (81% in twin births, 71% in triplet births, and 56% in quadruplet and higher births). The diagnosis of birth defects might be concordant or discordant for children in which all siblings had birth defects. The children from multiple births who had birth defects were generally preterm and had significantly lower birth weight. A higher fatality and mortality rate and longer hospital stay were also observed.

CONCLUSIONS

Overall, children from multiple births have an increased risk of birth defects.