CONTEXT Although the sex difference in eating disorder prevalence has typically been attributed to psychosocial factors, biological factors may also play a role. Prenatal testosterone exposure is a promising candidate, since it masculinizes behavior in animals and humans via its permanent effects on the central nervous system. OBJECTIVE To examine whether in utero testosterone exposure has ma...

1. Shared Environments of Twins The model estimated with the 6 types of siblings assumes that shared environmental effects are the same for twins and full siblings. Since twins share the same womb and are exact contemporaries, it could be argued that the environments of twins are more similar than that of full siblings. An alternative argument is that the environments of twins, who compete for ...

Previous studies based on population cohorts born at least 35 years ago, have reported appreciable childhood cognitive deficits for twins. We compared longitudinal IQ scores from approximately 188,000 singletons and some 6000 twins who went to primary school in the Netherlands from 1994 to 2003. In addition, we used a family-based design in which IQ scores of adult twins (N=196) were compared w...

Predictive relations between maternal variables and outcome status for 199 pairs of newborn twins were evaluated. The maternal independent variables included pregravid weight, weight at end of pregnancy, weight gain, age, parity, height, socioeconomic status, years of education, and body mass index. The twin dependent variables included birthweight, birth length, 5-min Apgar score, number of da...

BACKGROUND Cerebral palsy is more common in twins than singletons. Among twins, if one twin suffers a fetal death or dies in infancy, the prevalence of cerebral palsy in the surviving co-twin is considerably increased, and those from like-sex pairs are particularly at high risk. AIM To compare birthweight specific cerebral palsy prevalence in like-sex and unlike-sex twins where both twins sur...

Omphalopagus twins are conjoined twins sharing part of gastrointestinal system and abdominal wall. These types of twins have best chances of survival if successfully separated. We report a case of successfully separated omphalopagus twins at day six of life.

This paper examines why parents of twins or adult twins themselves request zygosity testing. Of 405 multiples including 8 sets of triplets, the majority (93%) were monozygotic. Age of testing ranged from 0 days to 73 years. About 50% of requests came from parents or twins who were curious about, or expressed a need to be certain of, their zygosity. Other reasons included health concerns (curren...

We studied twinning and fertility indices in mothers with spontaneous monozygotic (MZ) and dizygotic (DZ) twins and in mothers who conceived their twins after the use of assisted reproduction techniques (ART). Participants in this study consisted of 8,222 and 5,505 women with spontaneous DZ and MZ offspring and 4,164 and 250 women with ART DZ and MZ twin pairs, respectively. Women were compared...

The outcomes of 60 sets of monochorionic diamniotic (MCDA) twins were compared with 218 sets of dichorionic diamniotic (DCDA) twins. The caesarean section rates for MCDA were similar to those for DCDA twins (56.6 versus 53.6%, P > 0.1). Although the number of babies with 5-minute Apgar score of <7 was significantly higher for vaginally delivered MCDA twins compared with that of DCDA twins (12 v...

AIM To examine the concordance rates of common medical conditions and neurocognitive performance in monozygotic (MZ) and dizygotic (DZ) older twins. METHODS Twins aged ≥ 65 years and living in the three Eastern states of Australia were recruited through the Australian Twin Registry and underwent detailed neuropsychological and medical assessment. RESULTS Assessments were conducted on 113 MZ...