Higher Incidence of Hypospadias in Monochorionic Twins

• Published in: Twin research and human genetics 2015-10, Vol.18 (5), p.591-594
• Main Authors: Visser, Remco, Burger, Nienke C. M., van Zwet, Erik W., Hilhorst-Hofstee, Yvonne, Haak, Monique C., van den Hoek, Joop, Oepkes, Dick, Lopriore, Enrico
• Format: Article
• Language: English
• Subjects: Age; Birth defects; Birth weight; Gestational Age; Humans; Hypospadias - epidemiology; Incidence; Infant, Low Birth Weight; Infant, Newborn; Infant, Small for Gestational Age; Logistic Models; Male; Males; Medical records; Multivariate Analysis; Neonates; Regression analysis; Retrospective Studies; Risk factors; Twins; Twins, Dizygotic; Twins, Monozygotic; Ultrasonic imaging
• ISSN: 1832-4274; 1839-2628
• DOI: 10.1017/thg.2015.55

Background: Hypospadias is associated with twinning. The incidence of hypospadias in monochorionic and dichorionic male twins is, however, yet to be determined. Methods: All medical records of monochorionic and dichorionic twins admitted to our neonatal nursery between January 2004 and August 2013 were reviewed for the presence of hypospadias. Results: A total of 350 monochorionic and 303 dichorionic male twins were included in the study. The incidence of hypospadias in monochorionic and dichorionic groups was 4% (14/350) and 1% (3/303) (p = .016) respectively. In 11 of the 15 twin couples, hypospadias occurred in the twin with the lowest birth weight. The rate of hypospadias in twin infants small-for-gestational-age group was 10% (6/60) compared with 2% (11/593) in the appropriate-for-gestational-age group (p = .002). In a multivariate analysis, both monochorionicity and small-for-gestational-age were independently associated with hypospadias, odds ratio 4.1 (95% confidence interval (CI): 1.1–14.7) and 6.1 (95% CI: 2.2–17.2) respectively. Conclusions: The incidence of hypospadias is four-fold higher in monochorionic twins compared with dichorionic twins. Hypospadias is also independently associated with small-for-gestational-age.