In the present day societies where family planning and professional career development are prioritized, some women postpone childbearing until age of 30 or beyond. As a result, these women may have more difficulty conceiving. It is a commonly known fact that as a womans ages, the possibility of infertility increases.
Apart from age there are many other known causes of infertility in women. The various causes of infertility in women may be described under categories as under:
The uterine cervix plays an important role in the transport and functional maturation of the sperms deposited within the vagina. Cervical causes of infertility in women account for about 5-10% of cases.
Around the time of ovulation when the chances of pregnancy are the highest, the cervical mucus is profuse and thin in consistency which helps in smooth passage of the sperm into the uterine cavity. If the composition of the cervical mucus is hostile to the sperm, it will result in inability of the sperm to reach the ovum so as to fertilize it.
Rarely the cervical secretions may contain anti-sperm antibodies which may attack and kill the sperm. It is usually a immune reaction of the woman’s body against the foreign proteins contained in the sperm. It may make it difficult for the couple to conceive naturally and may have to take the help of assisted reproductive techniques.
Cervical stenosis refers to narrowing of the cervical opening. If the cervical opening is narrow, the semen deposited in the vagina is unable to gain access to the uterine cavity. Cervical stenosis may be congenital or acquired due to infections, radiotherapy and surgical procedures.
Uterus is the final destination of the embryo and it is where the fetus develops until birth. Uterine factors are responsible for about 2-5% of infertility.
Congenital uterine defects
Anatomical uterine defects may be present since birth. It may be in the form of septate uterus, unicornuate uterus etc. Such anomalies arise due to problems during development of the reproductive tract. Uterine anomalies lead to problems in implantation of the embryo.
Endometritis is the inflammation of the uterine lining. It may happen as a result of traumatic delivery, surgical procedures such as dilatation and curettage, or as consequence of instrumentation such as hysteroscopy. Successful implantation of an embryo does not happen if the uterine lining called the endometrium is inflamed and hostile.
Intrauterine adhesions may be formed as a rare complication of procedures such as dilatation and curettage. Such intrauterine adhesions may partially or completely obliterate the uterine cavity, leading to failure of conception .
Uterine polyps may be a harmless mucosal excrescence arising from the uterine lining. It may obstruct the cervical opening or the opening at the uterine end of the fallopian tube resulting in failure of transportation of the sperm for fertilization.
Uterine fibroids are over-growths of the uterine musculature. They may protrude into the uterine cavity. Distortion of the uterine cavity by the fibroid may result in difficulty in implantation of the embryo.
Ovaries are where the ovum or eggs are produced. Any dysfunction of the ovaries will result in infertility .
Ovarian insufficiency or premature ovarian failure is the inability of the ovaries to produce ovum in a woman younger than 40 years of age. In a woman older than 40 years of age, a physiological decline in the ovarian function is expected.
Polycystic ovarian syndrome
Polycystic ovarian syndrome is associated with hormonal imbalances and anovulatory menstrual cycles. Anovulation is the failure to ovulate during a menstrual cycle. The woman may find it difficult to conceive due to anovulatory cycles.
Dysregulation of hypothalamo-pituitary-ovarian axis
The production of ovum within the ovaries and release of ovum during a menstrual cycle is under the control of the hypothalamo-pituitary-ovarian axis. The hypothalamus releases gonadotrophin releasing hormone in pulses which in turn stimulates the pituitary gland to release luteinizing hormone and follicle stimulating hormone. The hormones act on the ovaries so as to stimulate production of ovum, secretion of female sex hormones estrogen and progesterone, ultimately resulting in ovulation. Any imbalance or disturbance in the level of hormones secreted from the hypothalamus, pituitary gland or the ovaries may result in ovulatory dysregulation and infertility.
Fallopian tubes play a major role in fertilization. The fallopian tubes pick up the ovum released from the ovaries and transport it towards the sperm. The process of fertilization of the ovum by the sperm also takes place in the fallopian tube. The fallopian tube later transports the embryo to the uterine cavity for implantation. Hence any abnormality of the fallopian tube can lead to infertility.
A blockage in the Fallopian tubes may be congenital or acquired. Acquired tubal block could be due to inflammation and scarring secondary to infections such as tuberculosis.
Elective tubal ligation for the purpose of family planning may result in permanent infertility. Though reversal of tubal ligation can be tried, success rates may be low.
Fallopian tubes may be congenitally absent in some women. It may be due to spontaneous torsion of the tubes in utero followed by necrosis and resorption .
If the woman has undergone salpingectomy in the past, Fallopian tube may be absent. Salpingectomy is the surgical removal of the Fallopian tube and is done in case of tubal pregnancy or tubal mass .
The uterus, ovaries and the Fallopian tubes lie bounded by the peritoneal cavity within the pelvis. Any abnormality of the pelvic cavity may result in difficulty in conceiving a baby.
Pelvic inflammatory disease
It is the infection of the upper reproductive tract in females. The most common causes of pelvic inflammatory disease are Chlamydia and gonorrhea infections. The infection may spread to whole of the pelvic cavity and the abdomen. The infection of the Fallopian tubes leads to scarring of the tubes leading to infertility.
Peritoneal adhesions and scarring may form due to infections or surgical procedures done in the past. Dense peritoneal adhesions may hamper the motility of the fallopian tubes. The impaired motility of the fallopian tubes result in failure of transportation of the ovum released from the ovaries leading to infertility issues.
Endometriosis is the presence of uterine lining tissue anywhere outside the uterine cavity. Endometriosis involving the fallopian tubes and ovaries may lead to infertility. The endometriotic tissue may damage the ovaries or the fallopian tubes and may also result in formation of adhesions. The endometriosis may also trigger an increase in the number of macrophage cells in the pelvis which may engulf the sperms. Mostly only severe endometriosis causes infertility.
Large pelvic masses may occupy space in the pelvic cavity hampering the accumulation of peritoneal fluid. Peritoneal fluid is necessary for the maintenance of the ovum after ovulation and it also facilitates pick up of the ovum by the Fallopian tube.
Lifestyle factors affecting fertility in women:
Many lifestyle practices which are prevalent in today’s world have been found to affect female fertility adversely. The various lifestyle and behavioural factors affecting fertility of a woman are described below.
Tobacco smoking alters the cervical mucus composition and the ciliary mechanism within the uterus and Fallopian tube, thereby interfering with transport of sperm.
Marijuana and its metabolite delta-9-tetrahydrocannabinol, inhibit the secretion of luteinizing hormone and follicle stimulating hormone in women thereby causing problems in ovulation.
Heroin, cocaine, and crack cocaine use has shown to put the user at higher risk for pelvic inflammatory disease.
Chronic alcoholism may lead to ovulatory dysfunction and impacts fertility in women.
Exercise and stress
Exercise in moderation should be encouraged. But if exercise is strenuous and compulsive, it not only increases stress levels but also may produce hormonal imbalance. Prolonged and vigorous exercise stimulates secretion of large amounts of endorphins which interfere with normal production of luteinizing hormone and follicle stimulating hormone. This in turn results in ovulation problems and failure to implant the fertilized embryo.
Extremes of body weight
Weight has an impact on fertility at either extreme. Extreme weight loss may lead to disturbances in hypothalamic hormone release. Obesity is known be associated with anovulation.
In some women the anxiety and depression associated with infertility itself may make it difficult for the woman to conceive naturally. Some studies have shown the link between stress and infertility but is not yet proven.
After having ruled out all the above mentioned possible causes of infertility , couples with unknown etiology can be categorized as unexplained infertility or normal infertile couple. In such couples, the actual cause for infertility cannot be detected and could be dysfunctional interaction between the sperm and ovum or some problem with the embryo at the genetic level.
We will be answering more of your queries on infertility through our upcoming blog articles.