Being fertile or fertility is the ability to conceive or induce conception. Infertility is the inability to conceive. The proper definition is the inability to become pregnant up to 12 months of regular unprotected sexual intercourse.
There are two main types of infertility:
- The failure of a couple to have any children at all is termed primary infertility.
- Couples who have already conceived, have produced a first child but have great difficulty in adding to their family are said to have secondary infertility.
Some doctors prefer the term sub-fertility to describe any form of
reduced fertility with prolonged time. It is important to remember that infertility can arise from female factors, male factors, or a combination of both. There are many factors affecting fertility for both males and females. It may be possible that you are looking for infertility treatments, the cost of IVF in major metro cities like Mumbai, success rates and so on. For this purpose, ClinicSpots will help you find the best infertility centre near you.
Fertilization is the term used to describe the successful fusion of a
female egg and male sperm to form the new organism that is the baby.
Female factors affecting fertility include hormones, oogenesis, implantation, and the potential for the pregnancy itself. Male factors affecting fertility include hormones, spermatogenesis, maintaining an erection, and ejaculation.
Steps in the workup of an infertile couple include obtaining a thorough medical and family history, occupational and lifestyle history, physical examination, laboratory testing, and evaluation of genetic factors that may affect one or more of these factors.
What is the chance of conceiving in a normally fertile couple?
The chance of falling pregnant increases as the months go by before it plateaus after about six months. A normal fertile couple has approximately 20 percent chance of achieving pregnancy in any one
month of unprotected intercourse and this greatly increases to about ninety percent of successful conception at about 12 months of unprotected sex. Therefore, a fertile couple can expect to achieve a pregnancy sometimes during the first year of trying.
What are some potential causes that of subfertility or infertility?
It is thought that male factors account for 30% of causes, female factors about 30%, a mix of both male and female 30% and the remaining 10% is the idiopathic or unknown origin.
In women, important organs that play a big role in female fertility include the brain and two important parts of the brain the hypothalamus and the pituitary gland.
There is also the female reproductive tract made up of the vagina, cervix, uterus, fallopian tube also known as the uterine tube and the ovary.
A region of the brain called the hypothalamus produces a hormone called gonadotropin-releasing hormone or GnRH for short which
stimulates the pituitary gland in the brain to produce two important hormones, follicle-stimulating hormone or FSH and luteinizing hormone or LH.
Follicle-stimulating hormone targets the ovaries and essentially stimulates some follicles within the ovary to develop in females
of reproductive age. There are many follicles ready to develop and, in each cycle, only some of these develop.
As the follicles develop and begin producing estrogen. Estrogen is an important hormone for the menstrual cycle. In high amounts estrogen actually will help stimulate luteinizing hormone production by the pituitary gland.
Luteinizing hormone targets the most developed follicle in the ovary causing ovulation. When the follicle ovulates, it releases the female egg into the fallopian tube. The female egg is now ready to be fertilized by the male sperm.
The post-ovulatory follicle then slowly degenerates and becomes the corpus luteum. As your corpus luteum degenerates it releases progesterone, another important hormone that prepares the body
For a potential pregnancy. Progesterone is thus known as the pregnancy hormone.
If fertilization of the female egg does not take place, the whole cycle continues again after the female menstrual. The female menstrual cycle is therefore divided into two phases, the follicular phase where the follicle matures and the luteal phase when the corpus luteum degenerates.
Female factors that affect any part of these phases or affecting any organ involved in these phases can cause infertility. The causes of
infertility can be broken down into five main groups:
- Pituitary Disorders: In the first example, the hypothalamus is unable to produce gonadotropin-releasing hormone properly. There is therefore not enough gonadotropin-releasing hormone to stimulate the production of follicle-stimulating hormone and luteinizing hormone from the pituitary gland. With no follicle-stimulating hormone, this means the follicles within the ovaries do not develop. With no luteinizing hormone, this means no ovulation will take place. This is an example of hypogonadotropic hypogonadism which is also classified as an ovulation disorder Type 1. A common cause here is the hypothalamic-pituitary failure.
Another example of a pituitary disorder is where there is overactivity of the hypothalamic-pituitary axis. Here, the hypothalamus produces gonadotropin-releasing hormones that stimulates follicle-stimulating hormone and later luteinizing hormone released from the pituitary gland.
But the problem is the ovary does not contain many follicles and because of this, there is no proper development of follicles. Not much estrogen being produced and so no ovulation will take place, this is called hypergonadotrophic hypogonadism which is also classified as an ovulation disorder type 3. An example in this case is ovarian failure.
The last type of pituitary disorder is due to another hormone called prolactin. The pituitary gland also produces prolactin, an important hormone for breastfeeding. However, due to a variety of reasons prolactin production may increase, and this is when it is called hyperprolactinemia. When there is high prolactin in the blood, it has a negative feedback on the hypothalamus inhibiting the production of gonadotropin-releasing hormone.
With low gonadotropin-releasing hormone, this means follicle-stimulating hormone and luteinizing hormones are not produced properly causing fertility problems. The actual causes of hyperprolactinemia include pituitary tumors producing more prolactin. Normally, a hormone produced by the hypothalamus called prolactin inhibitory factor or PIF inhibits prolactin production and secretion.
But if anything interferes with PIF, this means more prolactin can be produced. Certain medications can prevent prolactin inhibitory factor production. Tumors can also block prolactin inhibitory factor function thus leading to hypercholesterolemia. Finally, hypothyroidism can also stimulate prolactin production leading to hyperprolactinemia.
- Ovarian Disorders: An example here is a polycystic ovarian syndrome or PCOS for short. Polycystic ovarian syndrome is thought to be the most common cause of varying dysfunction in women of reproductive age. Polycystic ovaries are enlarged to smooth but thicker than normal outer cover with multiple cysts covering the ovary surface. The polycystic ovarian syndrome is also classified as an ovulation disorder type 2.
One of the main features of polycystic ovarian syndrome is hyperandrogenism. Any cause of hyperandrogenism where there are excess androgens in the blood can influence female menstruation and subsequently ovulation. Remember the female menstrual cycle can be divided into the follicular phase and the luteal phase.
Premature ovarian failure is defined as a cessation of menses prior to the age of 40. As a result of the depletion of primordial sites. Premature ovarian failure may occur due to genetic causes, autoimmune disorders, or destruction of ovaries by radiation therapy, chemotherapy, surgery, toxins, or unknown factors.
Luteal phase defects are defined as abnormalities of the corpus luteum function accompanied by insufficient progesterone production. Another proposed etiology for the condition is the inadequate effect of progesterone on the endometrium despite normal production.
- Ovulation Disorders: This was already discussed in the previous point. Type 1 is the hypogonadotropic hypogonadism. Type 2 ovulation disorder is a polycystic ovarian syndrome or PCOS for short. Type 3 ovulation disorder is hypergonadotrophic hypogonadism.
- Pelvic, Tubal, or Uterine Disorders: The causes of infertility include physical aberrations of the female reproductive system primarily as a result of disease or congenital defects. Occasionally, the consequent damage to the cervix, uterus, fallopian tubes, and ovaries is irreparable, making conception and pregnancy impossible.
An ectopic pregnancy occurs on the ovum, is fertilized and implants outside the uterus. Ectopic pregnancy has steadily increased in the last two decades as a result of the prevalence of sexually transmitted diseases and more rarely the use of intrauterine devices for contraception.
Endometriosis is defined as the presence of small implants of endometrial tissue and stroma abnormally embedded in tissue outside the individual cavity. A misplaced endometrial tissue may implant anywhere within the abdominal cavity and remain responsive to the hormones. Endometriosis does irritate surrounding tissue when menstruation occurs and may produce adhesions, scar tissue on the pelvis.
Tubal factors for infertility are the result of damage or blockage of the fallopian tubes and is a primary factor in up to 25% of an infertile woman. Tubal factors causing infertility can be caused by endometriosis, pelvic inflammatory disease, or sexually transmitted diseases.
Another potential cause of infertility is an abnormal cervical mucus. During a normal menstrual cycle, the cervical mucus secreted changes and is primarily driven by estrogens. With abnormality in cervical mucus production, it can cause problems in sperm penetrating through the cervix.
Uterine abnormalities account for about 10% of infertility with two% representing congenital anomalies. Anatomical abnormalities may include uterine leiomyomas also known as uterine fibroids and intra-uterine adhesions or Asherman’s syndrome. Mullerian anomalies can lead to uterine abnormalities such as septate uterus amongst many others.
- Unexplained infertility: It is defined as the lack of an explainable cause for the inability to conceive and occurs in up to 10% of infertile couples. This is known as idiopathic infertility.
It is important not to forget about the male factors which also play a role in infertility.