A twin pregnancy is when there are two fetuses in the uterus at the same time. Twins can be identical, meaning they developed when a single fertilized egg split early in development, or fraternal, ...

Identical (monozygotic) twins develop from a single egg-sperm combination that splits into two. If the split is delayed, usually a week or so after conception, the processes of growing a placenta, ...

Twins—smaller at birth, on average, than singletons—start out smaller in pregnancy than was previously known, according to a study by researchers at the National Institutes of Health (NIH). The ...

Being pregnant with twins can be exciting for many women, but the risks associated with multiple pregnancies can be frightening, particularly in Nigeria, where the healthcare system remains fragile, ...