The term coitus is derived from the Latin word coitio or coire, meaning "a coming together or joining together" or "to go together", and it describes a variety of sexual activities under ancient Latin names, but usually refers exclusively to penile—vaginal penetration. Lerner and Laurence Steinberg state that researchers also "rarely disclose how they define sex or even whether they resolved potential discrepancies in definitions of sex".
A study by the Kinsey Institute examined the definition of sex based on a random sample of college students from 29 U. Another study by the Kinsey Institute sampled people, ranging in ages 18— Human mating strategies and Pair bond Copulation ranges from a purely reproductive activity to one of emotional bonding.
For example, sexual intercourse and sexual activity in general often play a strong role in human bonding. One possible reason for this distinct biological feature may be formation of strong emotional bonds between sexual partners important for social interactions and, in the case of humans, long-term partnership rather than immediate sexual reproduction.
The resulting cooperation encourages collective tasks that promote the survival of each member of the group. Copulation corresponds to a succession of innate sexual reflexes: These copulatory reflexes are controlled by hormones and facilitated by sexual pheromones.
Non-primate females copulate only when in estrus ,  but sexual intercourse is possible at any time of the menstrual cycle for women. In this way, they stimulate themselves and each other, often continuing until orgasm in either or both partners is achieved. It is sometimes performed to the exclusion of all other forms of sexual activity, and may include the ingestion or absorption of semen or vaginal fluids.
The subsequent route of the sperm from the vault of the vagina is through the cervix and into the uterus , and then into the fallopian tubes. Millions of sperm are present in each ejaculation, to increase the chances of one fertilizing an egg or ovum see sperm competition. When a fertile ovum from the female is present in the fallopian tubes, the male gamete joins with the ovum, resulting in fertilization and the formation of a new embryo.
When a fertilized ovum reaches the uterus, it becomes implanted in the lining of the uterus the endometrium and a pregnancy begins. Artificial insemination is a form of assisted reproductive technology , which are methods used to achieve pregnancy by artificial or partially artificial means.
For gay male pairings, there is the option of surrogate pregnancy; for lesbian couples, there is donor insemination in addition to choosing surrogate pregnancy. Coitus interruptus There are a variety of safe sex methods that are practiced by heterosexual and same-sex couples, including non-penetrative sex acts,   and heterosexual couples may use oral or anal sex or both as a means of birth control.
Condoms are widely recommended for the prevention of sexually transmitted infections STIs. Penile—vaginal penetration is the most common form of sexual intercourse. However, sons are encouraged to gain experience with older women or prostitutes before marriage. Age of men at sexual initiation in these societies is at lower ages than that of women; this group includes Latin cultures, both from southern Europe Portugal, Greece and Romania are noted and from Latin America Brazil, Chile , and the Dominican Republic.
The study considered many Asian societies to also fall into this group, although matching data was only available from Thailand. In non-Latin, Catholic countries Poland and Lithuania are mentioned , age at sexual initiation was higher, suggesting later marriage and reciprocal valuing of male and female virginity. The same pattern of late marriage and reciprocal valuing of virginity was reflected in Singapore and Sri Lanka. The study considered China and Vietnam to also fall into this group, though data were not available.
Department of Health and Human Services , the average age of first sexual intercourse in U. Department of Health and Human Services reported in that teenagers are delaying sexual intercourse and other sexual activity until older ages. Some, in particular HIV and syphilis, can also be passed in other ways, including from mother to child during pregnancy and childbirth , through blood products , and by shared hypodermic needles. Untreated chlamydia infection can lead to female infertility and ectopic pregnancy.
Human papillomavirus can lead to genital and cervical cancers. Syphilis can result in stillbirths and neonatal deaths. Untreated gonococcal infections result in miscarriages , preterm births and perinatal deaths.
Infants born to mothers with untreated gonorrhea or chlamydia can develop neonatal conjunctivitis a serious eye infection , which can lead to blindness. The World Health Organization also stated that the "estimated 1. They added that "several co-factors may increase the risk of HIV transmission through oral sex"; this includes ulcers, bleeding gums , genital sores, and the presence of other STIs.
Approximately 46 million pregnancies per year reportedly end in induced abortion. However, many more women become pregnant and miscarry without even realizing it, instead mistaking the miscarriage for an unusually heavy menstruation. This data includes live births, abortions, and fetal losses.
It has been linked to atypical levels of dopamine, a neurotransmitter. This behavior is characterized by a fixation on sexual intercourse and disinhibition.
It was proposed that this 'addictive behavior' be classified in DSM-5 as an impulsive—compulsive behavioral disorder. Addiction to sexual intercourse is thought to be genetically linked. Those having an addiction to sexual intercourse have a higher response to visual sexual cues in the brain. Those seeking treatment will typically see a physician for pharmacological management and therapy.
It is manifested by hypersomnia and hypersexuality and remains relatively rare. Intravaginal ejaculation latency time and Coitus reservatus Sexual intercourse, when involving a male participant, often ends when the male has ejaculated, and thus the partner might not have time to reach orgasm. But he didn't ask if the men or their partners considered two minutes mutually satisfying" and "more recent research reports slightly longer times for intercourse".
It is a conditioned reflex of the pubococcygeus muscle, and is sometimes referred to as the PC muscle. Vaginismus can be hard to overcome because if a woman expects to experience pain during sexual intercourse, this can cause a muscle spasm, which results in painful sexual intercourse. However, doctors caution against the unnecessary use of these drugs because they are accompanied by serious risks such as increased chance of heart attack. This is especially true for women.
Even after extensive gynecological surgical procedures such as hysterectomy , oophorectomy , salpingectomy , dilation and curettage , hymenotomy , Bartholin gland surgery, abscess removal, vestibulectomy , labia minora reduction, cervical conization , surgical and radiological cancer treatments and chemotherapy , coitus can continue.
Reconstructive surgery remains an option for women who have experienced benign and malignant conditions. Sexuality and disability Obstacles that those with disabilities face with regard to engaging in sexual intercourse include pain, depression , fatigue, negative body image , stiffness, functional impairment, anxiety, reduced libido , hormonal imbalance, and drug treatment or side effects. Sexual functioning has been regularly identified as a neglected area of the quality of life in patients with rheumatoid arthritis.
Women with Intellectual disabilities ID are often presented with situations that prevent sexual intercourse. This can include the lack of a knowledgeable healthcare provider trained and experienced in counseling those with ID on sexual intercourse. Those with ID may have hesitations regarding the discussion of the topic of sex, a lack of sexual knowledge and limited opportunities for sex education.
In addition there are other barriers such as a higher prevalence of sexual abuse and assault. These crimes often remain underreported. There remains a lack of "dialogue around this population's human right to consensual sexual expression, undertreatment of menstrual disorders, and legal and systemic barriers". Women with ID may lack sexual health care and sex education. They may not recognize sexual abuse. Consensual sexual intercourse is not always an option for some. Those with ID may have limited knowledge and access to contraception, screening for sexually transmitted infections and cervical cancer.