Penileβvaginal intercourse , or vaginal intercourse , is a form of penetrative sexual intercourse in human sexuality , in which an erect penis is inserted into a vagina. Some of the synonyms are used for other variants of sexual intercourse as well. It corresponds to mating or copulation in non-human animals.
Various sex positions can be used. Following insertion, additional stimulation is often achieved through rhythmic pelvic thrusting or a gyration of the hips, among other techniques. The biological imperative is to achieve male ejaculation so that sperm can enter the female reproductive tract and fertilize the egg , thus beginning the next stage in human reproduction , pregnancy.
The desire for sensual pleasure is usually the main motivation for humans, and sometimes the wish to have a baby or more children. During coitus without a condom , sperm enter the vagina, first with the pre-ejaculate and then a larger amount through male ejaculation. Sperm swim through the cervix and the uterus into the fallopian tubes of the woman.
If they meet a fertilisable egg cell after or during an ovulation , or if an ovulation occurs hours or days later, one sperm can fertilize it. The resulting zygote develops into the early embryonic stages and, in the meantime, migrates from the fallopian tube into the uterus. The nidation of the embryo called blastocyst at this stage of development with the beginning of the production of hCG marks the beginning of a pregnancy.
For people who do not want another child, contraception has made it possible to separate vaginal intercourse from its biological function of procreation. Since there is no mating season estrus in humans, the partners can have penileβvaginal intercourse distributed over the menstrual cycle regardless of the time of ovulation, even when the woman is already pregnant and after the menopause.
