A pregnancy of two or more fetuses. Multiple fetuses can be the same (identical) or different (fraternal). The following increase the chance of multiple pregnancies: heredity (a family history of multiple pregnancy increases the chances of having twins); older age (women over 30 have a greater chance of multiple conception); high parity (having one or more previous pregnancies, especially a multiple pregnancy); race (African-American women are more likely to have twins); taking fertility drugs, and receiving fertility treatments to become pregnant.