Pediatrics International (2003) 45, 712–718 Original Article Physical and mental development of Turkish twins Z. BIRSIN ÖZÇAKAR, FIGEN SAHIN, UFUK BEYAZOVA AND SEBNEM SOYSAL Department of Pediatrics, Gazi University Medical School, Ankara, Turkey Abstract Background: Multiple gestations are known to bring some risks in the prenatal and natal period, but whether it is a risk for development in childhood is a matter of debate. The aim of the present study was to evaluate physical and mental development of Turkish twins and then to assess whether being a twin poses risks for their development. Methods: Fifty-two twin pairs (104 children) aged between 1 and 5 years were enroled in the study. The control group consisted of 91 singletons, who were matched according to age, sex, gestational week and maternal educational level. The Denver Developmental Screening Test (DDST) was administered to assess cognitive development. Student t-test and χ 2 test were used to compare the two groups. Results: The mean age of the mothers of twins did not differ from that of singleton mothers ( P > 0.05). Twins were more frequently born in cases of assisted fertilization and were more often born via cesarean section. The birthweights of twins were lower and they were more frequently hospitalized after birth. The breast feeding period was shorter in twins and they had more chronic diseases than singletons (P < 0.05). Mothers of twins needed more help while caring for their infants. Physical development of twins and singletons did not differ statistically (P > 0.05). Twins had more suspect and delayed results in the DDST, especially in the language section of the test. Conclusion: Physical and mental development of twins does not differ significantly from singletons except that twins might have a tendency towards slow language acquisition. Key words mental development, physical development, twins. There have always been some naturally occurring multiple pregnancies; however, the frequency of multiple births has increased enormously in recent years because of mothers delaying their pregnancies to later ages and the increased use of assisted reproductive techniques. 1,2 Twins are often studied in genetics-based studies, but they are also uniquely useful for development-based studies. Multiple gestations are associated with problems in the prenatal, natal and postnatal periods. 3–5 There are also some arguments that twinning can have risks associated with later life. Several studies have found that being a twin is a risk factor for physical and mental development; 6–9 however, other studies conclude this is not the case and have found that the physical and mental development of twins is no different to that of other children. 10–12 The aim of this study was to evaluate physical and mental development of Turkish twins, and to assess whether twinning poses risks for physical or mental development. Our study is the first report regarding the development of twins in Turkey. Methods The present study comprised all twin pairs which have been registered and seen in Gazi University Medical Faculty, Department of Pediatrics, since 1996. Fifty-two twin pairs (104 children) aged 1 to 5 years were contacted and invited to the hospital with their parents. As a control group, 91 singletons matched according to age, sex, gestational week and maternal educational level were chosen from the children that had been seen at the same hospital. Diseases of more than 6 months duration were accepted as chronic diseases. In order to evaluate physical development, weight and height of all children, and head circumference of the children aged <18 months were measured by the same pediatrician and corresponding percentiles were noted. In order to evaluate mental development, the Denver Developmental Screening Test II (DDST) was administered by the same psychologist to all children. DDST is used to Correspondence: Z. Birsin Özçakar, Yeni Ankara Sokak 27/1 Cebeci, Ankara, Turkey. Email: lozcakar@yahoo.com Received 27 August 2002; revised 8 April 2003; accepted 30 May 2003.