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, ...

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 ...

NEW YORK (Reuters Health) - In a small new study, women pregnant with twins who gained more weight than current guidelines suggest were not at higher risk of serious pregnancy complications and they ...