Fraternal twins at two weeks old. The technical term for "fraternal" is "dizygotic" (twins) or "polyzygotic" (triplets or higher order). Fraternal twin sisters taking a nap. Nonidentical twins, the most common kind of<unk>  among humans, occur in about1out of every 80 pregnancies. Terms used for the number of offspring in a<unk> , where a number higher than three ends with the suffix -(a/u)plet: *two offspring – twins *three offspring – triplets *four offspring – quadruplets *five offspring – quintuplets *six offspring – sextuplets *seven offspring – septuplets *eight offspring – octuplets *nine offspring – nonuplets *ten offspring – decuplets Terms used for<unk> s or the genetic relationships of their offspring are based on the zygosity of the pregnancy: * Monozygotic –<unk>  (typically two) fetuses produced by the splitting of a single zygote * Polyzygotic –<unk>  fetuses produced by two or more zygotes: * Dizygotic –<unk>  (typically two) fetuses produced by two zygotes * Trizygotic – three or more fetuses produced by three zygotes * Sesquizygotic – an egg which is fertilized by 2 sperms, which produce 2 fetuses<unk>  pregnancies are also classified by how the fetuses are surrounded by one or more placentas (chorionicity) and amniotic sacs (amnionicity).
Multiple birth
Male lactation
Male pregnancy
Abortion in Europe
History of abortion
Preterm birth
History of birth control
Sexual activity during pregnancy