Multiple births or "multiples" refer to the delivery of more than one baby from a single pregnancy. There are several synonyms for multiple births such as multiple pregnancies, fetal multigestation, and multifetal gestation. Some of these terms are technical and may only be used in medical contexts. Other synonyms for multiple births include twin births, triplet births, quadruplet births, and higher-order multiple births. These terms refer to specific numbers of babies born in one pregnancy. Another term that is sometimes used as a synonym for multiple births is "superfecundation" which refers to the conception of multiple embryos at different times during a single menstrual cycle.