Got multiples on the way? Here’s what you need to know about when and how much you’ll feel your twins move.

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 ...

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, ...