“Are we having a boy or girl?” is one of the first things prospective parents wonder about the most. During pregnancy, couples wanting to know the sex of the future child may use ultrasound, chromosome analysis or testing of fetal DNA in maternal blood early in pregnancy, to find out the answer months before delivery. An estimated 50–70% of parents want to learn the sex of their future child du...

Sex determination is a fundamental developmental pathway governing male and female differentiation, with profound implications for morphology, reproductive strategies, and behavior. In animals, sex differences between males and females are generally determined by genetic factors carried by sex chromosomes. Sex chromosomes are remarkably variable in origin and can differ even between closely rel...

Same-sex pairing is widespread among animals but is difficult to explain in an evolutionary context because it does not result in reproduction, and thus same-sex behaviour often is viewed as maladaptive. Here, we compare survival, fecundity and transition probabilities of female Laysan albatross in different pair types, and we show how female-female pairing could be an adaptive alternative mati...

Most research on the stability of adult relationships has focused on coresidential (cohabiting or married) unions and estimates rates of dissolution for the period of coresidence. Studies examining how the stability of coresidential unions differs by sex composition have typically found that same-sex female couples have higher rates of dissolution than same-sex male couples and different-sex co...

INTRODUCTION Sexually transmitted infections are among the most important public health problems in the world. People who indulge in unsafe sex, such as female sex workers are the most at risk population groups due to multiple sexual partners and inconsistent condom use. The aim of this study was to assess condom utilization and sexual behavior of female sex workers in Gondar town, Northwest Et...

Sexually selected traits are predicted to show condition dependence by capturing the genetic quality of its bearer. In separate-sexed organisms, this will ultimately translate into condition dependence of reproductive success of the sex that experiences sexual selection, which is typically the male. Such condition dependence of reproductive success is predicted to be higher in males than female...

We investigated whether and how recipient-donor sex affects transplantation outcomes of 11,797 patients transplanted between 2008 and 2010. Thirty-seven percent were male recipients with male donors, 21% male recipients with female donors, 25% female recipients with male donors, and 17% female recipients with female donors. In multivariable analyses, male recipients had inferior overall surviva...

In bovine preimplantation development, female embryos progress at lower rates and originate smaller blastocysts than male counterparts. Although sex-specific gene expression patterns are reported, when and how sex dimorphism is established is not clear. Differences among female and male early development can be useful for human assisted reproductive medicine, when X-linked disorders risk is det...

PROBLEM Several pregnancy complications have disparities based on the sex of the fetus. It is unknown whether the sex of the fetus differentially alters the maternal immune milieu, potentially contributing to the observed differences. METHOD OF STUDY Using maternal plasma collected during 38 uncomplicated pregnancies (19 males, 19 females), we compared levels of cytokines, sex hormones, and a...

BACKGROUND A low female-to-male ratio has been observed in different Asian countries, but this phenomenon has not been well studied among immigrants living in Western societies. In this study, we investigated whether a low female-to-male ratio exists among Indian and Pakistani immigrants living in Norway. In particular, we investigated whether the determination of sex via ultrasound examination...