Most beings in the universe belonged to one of two sexes, or genders (namely male or female), which determined sexual and physiological traits.

Many sentient and non-sentient species had male and female sexes, with many biological and childbearing similarities between the two. Humans and other humanoid lifeforms generally reproduced by the coupling of a male and female, from which the female would give birth to male or female children. A female could have multiple children over her lifetime and some were capable of giving birth to several at once. Complications during pregnancy could be disastrous for a female, resulting in permanent disability or death.