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, ...

The risk of being admitted to the hospital with heart disease is twice as high the year after birth for mothers of twins compared to singleton births, according to new research. The risk is even ...