The Vagina's Role in Sex and Reproduction

Understanding Its Function From Arousal to Childbrith

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The vagina has many functions and plays a role in sexual arousal and pleasure, reproduction, and childbirth.

The vagina is a muscular tube that provides the passageway from the outside of the body to the uterus (womb). Your vagina can change in size to accommodate sexual intercourse and provide the "birth canal" through which a baby can be delivered.

This article discusses the vagina's function in reproduction and sexual intercourse, as well as its anatomy.

woman consults with her gynecologist in the gynecologist's office
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Vagina Function and Anatomy

The vagina is composed of tissues, fibers, muscles, and nerves.

The outermost mucosal tissue is underpinned by a layer of connective vaginal tissue which work together to produce mucus for a type of vaginal discharge called lubrication. Beneath these is a layer of smooth muscle, which can contract and expand, followed by another layer of connective tissue known as the adventitia.

The vagina is positioned between the vulva (the external genitalia) and the cervix (the narrow, neck-like passage which separates the vagina from the uterus).

The general anatomy of the vagina is as follows:

  • The opening of the vagina lies between the anus and the opening of the urethra (through which urine exits the body). The vaginal and urethral openings are protected by the labia.
  • Right below the urethra lies the introitus, also referred to as the vestibule or the opening to the vagina.
  • The vaginal canal then travels upward and backward, between the urethra at the front and the rectum at the back.
  • At the far end of the vaginal passage, the ectocervix (the external portion of the cervix) bulges prominently into the vaginal canal.

The length of the vagina can vary in your child-bearing years from between 2.5 inches to 3.5 inches on average.

The Vagina and Sexual Intercourse

During sexual arousal:

  • The mucosal membranes of the vagina will begin to produce more lubrication as the vagina expands both in length and width. This reduces the friction and risk of injury during vaginal penetration.
  • The vagina can continue to lengthen as you become fully aroused. The cervix takes the opposite tack and begins to retract. This can cause your uterus to rise into the pelvis and create the "ballooning effect" in which the vaginal walls stretch and contract around whatever is penetrating it.

The vagina itself does not have many nerve endings which is why you may be unable to achieve orgasm from vaginal penetration alone. On the other hand, the clitoris is rich in nerves and can work in tandem with the vagina to achieve orgasm.

The Vagina in Childbirth

During childbirth, the vagina provides the passageway through which the baby is delivered. When labor begins, you will typically experience vaginal discharge, labor contractions, and the rupture of membranes, which is also known as your water breaking.

As delivery approaches:

  • The cervix will begin to thin and soften, allowing the baby to drop into the pelvis.
  • The baby will then begin to lose the support of the cervix as contractions start and the cervical opening begins to dilate.
  • When the cervical dilation is larger than four inches (10 centimeters), the baby will pass from the uterus into the vagina. The structure of the vagina is such that it is able to stretch to many times its normal diameter to allow a full-term baby to be delivered.
  • Following pregnancy and the return of the normal estrogen flow, the vagina will return to its approximate pre-pregnancy state in around six to eight weeks.

During your menstrual cycle, the mucous membrane thickens and the mucus changes to assist fertilization. If you don't become pregnant, period blood will eventually flow out of your body through the vagina.

Summary

Your vagina's anatomy allows it to have many functions. These include a role in sexual arousal and intercourse, reproduction, and childbirth.

The vagina is a muscular tube that is able to adjust in size and produce different types of vaginal discharge depending on its role.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Boston University School of Medicine, Sexual Medicine: "Female Genital Anatomy"

  2. University of California, Santa Barbara, SexInfo Online: "Overview of the Female Reproductive System"

  3. Edwards D, Panay N. Treating vulvovaginal atrophy/genitourinary syndrome of menopause: how important is vaginal lubricant and moisturizer composition?. Climacteric. 2016;19(2):151–161. doi: 10.3109/13697137.2015.1124259

  4. Myers KM, Feltovich H, Mazza E, et al. The mechanical role of the cervix in pregnancy. J Biomech. 2015;48(9):1511–1523. doi: 10.1016/j.jbiomech.2015.02.065

Additional Reading
  • Schuiling, K. and Likis, F. (2016) Women's Gynecological Health (Third Ed.) Burlington, Massachusetts: Jones and Bartlett Learning. ISBN-13: 978-1284076028.

By Jennifer Whitlock, RN, MSN, FN
Jennifer Whitlock, RN, MSN, FNP-C, is a board-certified family nurse practitioner. She has experience in primary care and hospital medicine.