Written by:

Dr Aynsley Cresswell

BA (Oxon), BMBCh, DRCOG, DFSRH, MRCGP

Dr Cresswell is a general practitioner in the North East having recently moved to Yorkshire from Oxford. Aynsley has a special interest in women's and sexual health, and she has gained diplomas in both of these specialist areas. She has a keen interest in teaching and also enjoys caring for patients with long-term health conditions in her day-today practice.

The Reproductive System (Male and Female) and How to get Pregnant

In this article:

  • The female reproductive system
  • The Female reproductive system: main functions
  • The male reproductive system
  • Conception (getting pregnant)
  • Trying to get pregnant and infertility
  • What causes infertility in men?
  • What increases the risk of male infertility?
  • What causes infertility in women?
  • What increases a woman’s risk of infertility?
  • When to seek help and investigation
  • Main points
  • Conclusion

The Reproductive System (Male and Female) and How to get Pregnant

This article focuses on the reproductive system in men and women. It will help you understand what the reproductive organs are, how they work, and how fertilisation and conception occur. Lastly, it will discuss the factors within this process which may contribute to infertility and when to seek medical advice. It will be useful to have an understanding of this if you are trying to get pregnant.

The female reproductive system

The female reproductive system is made up of internal and external reproductive organs. These are found in the pelvic area (lower part of the abdomen below the level of the belly button) and together they give a woman the ability to produce and carry a developing baby (fetus).

The external female reproductive organs (those outside the body) are sometimes collectively called the vulva. These include the opening to the vagina, the end of the urethra (tube that you pass urine from), the inner and outer lips (labia) and the clitoris. The clitoris is highly sensitive and when touched causes arousal and orgasm. Also included are the mon pubis (the bulge above the labia that becomes covered with pubic hair at puberty) and the Bartholin’s glands which sit on either side of the opening of the vagina and which make a lubricant to moisten the vagina for sexual intercourse.

The internal organs (those inside the body) include the ovaries, fallopian tubes, uterus (womb), cervix and vagina.

THE OVARIES: Females have one ovary on each side of the uterus (womb) within the pelvis. At birth, women have about 2 million eggs in each almond-shaped ovary but throughout reproductive life only 400-500 eggs will be released at ovulation. As a woman gets older and ages towards menopause, the number and quality of her eggs declines meaning conception can be more difficult.

The ovaries also control sexual development and reproduction. The ovaries are responsible for the production of the female sex hormones (chemical messengers) oestrogen and progesterone (see below).

THE FALLOPIAN TUBES: There are also two fallopian tubes on either side of the uterus, which sit near the ovaries. These are very fine channels about 10cm long which have a funnel-shaped end which picks up the egg released by the ovary. The egg is then moved along the tube by wave-like motions of tiny hairs within the lining of the tube. As the tubes are so thin, they can be easily damaged or blocked by infection.

THE UTERUS: The uterus (or womb) is where the developing baby grows when a woman conceives (gets pregnant). Without a fetus inside, it is the size of a small pear and is hollow, very stretchy and made up of strong muscle tissue. It is held in place in the pelvic cavity by ligaments and muscle.

THE CERVIX: This is the lower part of the uterus that connects to the vagina. It forms a barrier between the two structures, however, sperm released by a man during sexual intercourse must swim from the vagina to the cervix to reach an egg. Within the cervix, there are small mucus-producing glands and the amount and thickness of the mucus changes throughout a woman’s menstrual cycle. When an egg has been released at ovulation, and the woman is at her most fertile, the mucus becomes thinner and stretchy, and changes to a clear colour. This change (from a thicker creamy discharge) allows sperm to pass through the cervix and reach the egg more easily. It is the cervix, plugged with a thick mucous plug that protects the developing fetus from infection and prevents its early delivery. During birth, the cervix expands and the baby passes through it.

THE VAGINA: The vagina is the muscular tube connecting the cervix to the vulva. The vagina receives the penis during intercourse and is the passage through which a baby is delivered. It tilts upwards and toward the small of the back, sitting between the urethra at the front and anus at the back.

The Female reproductive system

The Female reproductive system: main functions

Overall, the female reproductive system works to produce eggs (ova) so that they can be fertilised. The reproductive organs then provide the space and conditions for a developing fetus. As above, we have seen that women possess the internal structures necessary to allow the sperm from a man to meet the egg from a woman.

The female reproductive system makes its own hormones and these control the monthly menstrual cycle in a process called ovulation. If one of the eggs is fertilised by a male sperm this leads to pregnancy. The hormones also act to ensure that there are the right conditions in the womb for the baby to develop and to ensure that no further eggs are released during pregnancy.

The reproductive cycle in women is controlled by three hormones from the brain (GnRH, FSH and LH) and two from the ovaries (oestrogen and progesterone).

The brain produces Gonadotrophin-releasing hormone (GnRH) in an area called the hypothalamus. GnRH is the master hormone and acts on another part of the brain where it controls the release of follicle-stimulating hormone (FSH) and luteinising hormone (LH). FSH is released by the anterior pituitary and is carried by the bloodstream to the ovaries where it encourages the immature eggs to start growing. LH is also released by the anterior pituitary and travels to the ovaries. LH triggers ovulation and encourages the formation of a special group of cells called the corpus luteum.

Oestrogen is produced by the maturing ova (eggs). It helps to regulate the level of GnRH, FSH and LH to avoid too many mature ova being produced. Oestrogen also helps develop and regulate the female reproductive organs and structures.

Progesterone is mainly released by the corpus luteum. In tandem with oestrogen, it thickens the endometrium ready for implantation of the fertilised egg and helps with preparing the breasts to produce milk. It is the level of progesterone that controls the level of GnRH, LH and FSH.

If the egg is fertilised, the corpus luteum continues to produce hormones. Another hormone called human chorionic gonadotrophin (hCG) maintains the corpus luteum. The cells covering the fertilised egg (embryo) produce hCG which is the hormone detected in pregnancy tests.

If the egg is not fertilised, the corpus luteum breaks down and releases fewer of its hormones. The levels of progesterone and oestrogen fall and then cannot inhibit the levels of GnRH, FSH and LH which in turn increase. This marks the beginning of a new cycle as they encourage the new eggs to develop. The progesterone within the womb causes the release of chemicals that causes its lining to break away and this is the blood flow experienced during menstruation.

The length of every woman’s cycle can be different but is normally between 24-35 days. The first day of the period is known as day 1 of the cycle. The release of the egg within the cycle is the pivotal stage, and this normally happens on day 14 of a 28 day cycle.

The male reproductive system

The male reproductive system

The male reproductive organs are found mainly outside of the body and include the penis, and the testicles and scrotum, as well as spermatic ducts and sex glands.

THE PENIS: There are two main parts to the penis: the head and the shaft. The head is covered in a sleeve of skin known as foreskin (some men have this removed in a surgical procedure called circumcision). Urine and semen come out of the penis. Normally the penis is in a relaxed state but, when the man is sexually aroused, it can become erect, growing longer and wider as it fills with blood. During this process the foreskin also stretches, leaving the head exposed. The urethra is the tube inside the penis that carries urine or semen. It is the continuation of the sperm duct.

THE TESTICLES (TESTES): There are two testes (singularly: testis) which are held in place by the scrotum (scrotal sac – bag of skin). Each is connected to the abdomen by a spermatic cord and a cremaster muscle. The job of the testes is to produce millions of male cells called sperm and also to make male reproductive hormone, testosterone. The testes are ellipsoid glandular organs about two inches in length. The cremaster muscle can contract and relax along with the scrotum to allow temperature regulation of the testes (by pulling them closer to the body for warmth). The inside of the testes has many small compartments called lobules containing stem cells that can divide to produce sperm (spermatogenesis). Sperm are made up of three parts: the head (containing the chromosomes), the middle, and the tail, which helps sperm to move quickly to reach the egg.

THE SCROTUM: The scrotum is combination of two pouches side-by-side with a testis in each, located in the pubic region below the penis. As above, when the testes become too warm to be able to produce sperm the scrotum relaxes and moves away from the body’s heat. It can contract to be closer to the body’s core temperature when the testes get too cold.

THE EPIDIDYMIS: When the sperm has been made it is stored in the epididymis which is a structure which sits around the top and back edges of the testes. In total, it is made up of several feet of tightly coiled narrow tubes. The sperm mature here before travelling through the other reproductive organs.

SPERMATIC CORDS AND VAS DEFERENS: The spermatic cords connect the testes to the abdomen and these contain the vas deferens together with the nerves, lymph drainage and blood vessels that help the testes to work. The vas deferens is the tube of muscle that takes sperm away from the epididymis and into the ejaculatory duct. It is slightly wider than the epididymis and so can store the mature sperm.

EJACULATION: At ejaculation the sperm passes out of the vas deferens to the penis and then outside the body via the urethra. As it travels, fluid made from the seminal vesicles and prostate gland is added to the sperm. This helps transport the sperm and feed it, to keep it healthy on its way to the egg, and this gives it its white appearance. In each ejaculation there is on average 2-4ml of semen and each ml contains up to 10 million sperm. Further, just before each ejaculation a small amount of lubricant is produced by the Cowper’s glands. This leaks out of the penis before ejaculation and may contain sperm. This helps prepare for ejaculation. At the moment of ejaculation, the semen is thick, but after a few minutes it becomes more liquid which helps release the sperm as they travel toward the ova.

Conception (getting pregnant)

Conception is the process that begins at fertilisation of the egg and ends when this egg implants within the womb.

For fertilisation, the egg needs to come in contact with a sperm, usually through sexual intercourse.

Sperm are able to wait in the uterus and fallopian tube until ovulation and can survive for up to seven days, but the egg may meet the sperm within minutes or hours of ovulation. Eggs only live for up to 24 hours so the chance of getting pregnant is increased if the sperm are already waiting. If you are having sex 2-3 times per week then you are helping to ensure that there is sperm always waiting. Importantly, the average couple will take 3-6 months to conceive if they are having sex this often.

The sperm attaches itself to an egg and then manages to dissolve the outer coating of the egg by producing a specific substance. Only one sperm enters the egg and then the egg coating is repaired to stop any more getting in. It is once the sperm is fully inside the egg that fertilisation occurs. This fertilised egg travels along the fallopian tube to the womb where the embryo can attach itself to the endometrium. This is called implantation. Once this occurs conception is complete, and the pregnancy begins. The whole time from ovulation to implantation is around 5-10 days.

Occasionally an embryo does not make it to the uterus and begins to develop elsewhere, normally in the fallopian tube. This is known as an ectopic pregnancy.

Trying to get pregnant and infertility

If you are trying to get pregnant the main thing is to ensure regular sexual intercourse 2-3 times per week and remember that on average it takes between 3- 6 months to conceive if both male and female partners have good reproductive health. In general, infertility is defined as not being able to conceive after one year (or longer) of unprotected sex. To conceive, a woman’s body must release an egg from one of her ovaries, a man’s sperm must join with the egg along the way and it must pass through the fallopian tube towards the uterus where it must implant. Infertility may result from a problem with any or several of these steps. Importantly, infertility is not always a woman’s problem and both sexes can contribute. In about 35% of couples with infertility, a male factor is identified along with a female factor. In about 8% of couples, a male factor is the only cause.

What causes infertility in men?

To evaluate where the problem lies, a semen analysis is performed. The number of sperm (concentration), motility (movement) and shape (morphology) are assessed under the microscope. A slightly abnormal analysis does not mean that a man is infertile. Instead, an analysis helps work out if and how male factors are contributing to infertility.

The main reasons for male infertility include:

  • Disruption of testicular or ejaculatory function (eg trauma to the testes can affect the number of sperm, unhealthy habits such as heavy alcohol use, smoking or anabolic steroid use and medical conditions such as diabetes or cystic fibrosis can contribute).
  • Hormonal disorders (such as problems with the function of the hypothalamus or pituitary glands which produce the normal hormones which control testicular function).
  • Genetic disorders (such as Kleinfelter’s syndrome or Y-chromosome microdeletion which both cause no or low numbers of sperm to be produced).

What increases the risk of male infertility?

There are some common factors which affect fertility in men. These include:

  • Older age – couples where the male partner is over 40 are more likely to report difficulty conceiving.
  • Being overweight or obese
  • Smoking and excessive alcohol
  • Use of illicit drugs and marijuana
  • Exposure to certain medications, radiation, cancer treatments or environmental toxins such as pesticides
  • Frequent high temperatures around the testes such as men in wheelchairs or frequent sauna use

What causes infertility in women?

If we think about having healthy anatomy, a woman needs functioning ovaries, fallopian tubes and a uterus to get pregnant. There are a number of reasons a woman may find it difficult to conceive.

Ovarian dysfunction: as detailed above, on average a menstrual cycle is 28 days long. A woman with irregular periods is likely not ovulating. Disruption to ovulation may be caused by several conditions and warrants further investigation by a doctor. These include:

  • polycystic ovarian syndrome (PCOS)
  • diminished ovarian reserve (DOR)
  • functional hypothalamic amenorrhea (FHA)- caused by excessive exercise, stress, or low body fat which is sometimes associated with eating disorders such as anorexia.
  • improper function of the hypothalamus and pituitary glands
  • premature ovarian insufficiency (POI)- sometimes referred to as premature menopause where the ovaries fail before a woman is 40
  • menopause – the age-appropriate decline in ovarian function which usually occurs around the age of 50

Fallopian tube obstruction: risk factors can include a history of pelvic infection, history of ruptured appendicitis, history of gonorrhoea or chlamydia, known endometriosis or a history of abdominal surgery. Tubal evaluation can be carried out using an X-ray called a hysterosalpingogram (HSG) or chromopertubation (CP) in a small surgical procedure.

Abnormal uterine contour: the uterus may be evaluated by transvaginal ultrasound to look for fibroids or other anatomical abnormalities

What increases a woman’s risk of infertility?

Female infertility is known to increase with:

  • advancing age – about one third of couples in which the woman is older than 35 years have fertility problems. Aging also increases a woman’s chances of miscarriage and of having a child with genetic abnormalities. With age, a woman has fewer eggs left, the eggs are not as healthy, and she is more likely to have health conditions that can cause fertility problems.
  • smoking and excessive alcohol use
  • extreme weight gain or loss
  • excessive physical or emotional stress that results in amenorrhoea (absent periods)

When to seek help and investigation

If women are younger than 35, most doctors will suggest at least one year of unprotected sexual intercourse before seeking help for fertility. For women over 35, couples should see a doctor after six months. As mentioned, there are some health problems which increase the risk of infertility, so speak to your doctor if you have any of the following signs or symptoms:

  • irregular periods or no periods
  • very painful periods
  • endometriosis
  • pelvic inflammatory disease
  • more than one miscarriage
  • or there is a suspected male factor (e.g. testicular trauma, chemotherapy or infertility with another partner)

Main points

  • The female reproductive system is made up of external and internal body parts including the ovaries, fallopian tubes, uterus, cervix and vagina.
  • The male reproductive system is made up of mainly external body parts i.e. the penis, testicles and scrotum. Internal structures including the epididymis, spermatic cords and vas deferens store and then transport sperm ready for ejaculation.
  • Fertilisation occurs when an egg ova (produced by the female reproductive organs) meets a sperm (produced by the male reproductive system) typically following sexual intercourse and the sperm penetrates the egg.
  • Conception occurs when the fertilised egg implants itself in the lining of the uterus.
  • It takes around five to ten days from ovulation (the production of an egg in the woman’s ovaries) to implantation.
  • If an embryo (fertilised egg) does not make it the uterus it can begin to develop elsewhere and this is known as an ectopic pregnancy.
  • There are a number of reasons why it might be difficult for a woman to conceive. These may be attributable to infertility in the man or the woman.
  • Causes of female infertility include ovarian dysfunction, fallopian tube obstruction and abnormal uterine contour.
  • Causes of male infertility include disruption of testicular or ejaculatory function, hormonal disorders and genetic disorders.

Conclusion

This article gives an overview of the male and female reproductive systems and the steps involved in fertilisation which can be useful in understanding how to get pregnant.

If you are having trouble conceiving, do seek help from your GP.  Around one in seven couples may have difficulty; approximately 3.5 million people in the UK. Remember, around 84% of couples will get pregnant naturally within a year if they have regular unprotected intercourse (every two or three days), but for couples who’ve been trying to conceive for more than three years without success, the likelihood of getting pregnant naturally within the next year is 25% or less.

There are many steps in the process of conception as we have mentioned and there is plenty you can do to keep your reproductive system healthy (see above). However, there can be underlying reasons other than lifestyle which may affect your chances of conceiving naturally.