Causes of Female Infertility

INTRODUCTION
To have a healthy pregnancy and to carry that pregnancy to term is a very complicated process. If something goes wrong during this process, it can lead to infertility.

DEFINITION:
When a sexually active couple, is unable to get pregnant even after one year of unprotected sexual intercourse, is considered infertile. If we talk about distribution of causes among females and males, about 40% of cases are due to female factors, 30% are due to male factors, 20% are a combination of both, and in about 10%, the cause is unknown also referred to as unexplained infertility.

Lets try to understand how a natural pregnancy happens :

• Oocyte or egg forms and attain an adequate size in either of the ovaries.
• Egg is released each month and relation of fallopian tube and ovary should be normal so that egg can come into the tube.
• A sperm if present in fallopian tube it fertilize the egg.
• Fertilised egg travels through the fallopian tubes and attach (implant) in the lining of the uterus.
  If there is a problem at any step, infertility can happen.

Chances of getting pregnant are affected by the length of sexual exposure, frequency of coitus, and couple’s age. Young aged couples have 25% chances to conceive after 1 month of unprotected intercourse; 70% of the couple’s conceive by 6 months, and 90% of the couples conceive by 1 year. Only 5% of the couples will conceive after one and a half year or two years. Frequency of coitus twice weekly is considered adequate. Chances of getting pregnant decrease after 35yrs of age in females. So, if a female marries after 35 yrs, investigations should be initiated after 6 months.

In this article we will discuss mainly female factors responsible for infertility.

Causes of female infertility can be divided into three broad categories. These categories are further discussed below in detail.

1. Defective Ovulation :

It occurs because of the following causes:

A) Endocrine disorders: The dysfunction of hypothalamus and pituitary gland can lead to an excess amount of prolactin or deficiency of FSH or LH, this may prevent ovulation. Adrenals and thyroid may also delay ovulation. In luteal phase defect, when there is inadequate production of progesterone by the corpus luteum, the fertilized egg may not be able to implant , therefore causing infertility.

B)Physical disorders: Certain physical disorders such as obesity, anorexia nervosa, and excessive exercise may lead to overweight or malnutrition, and later abnormal menstrual cycle.

C)Ovarian disorders: Polycystic ovarian disease (PCO) can lead to infertility because of an increased amount of testosterone and reversal of LH:FSH ratio that hinder formation of dominant follicle from the ovarian follicles, causing to formation of multiple cysts in ovaries thus leading to irregular cycles and female infertility.

D)Endometriosis: In this condition, uterine lining(endometrium) implants outside uterine cavity i.e; in ovaries, fallopian tubes or pelvis or vagina. These implants form fluid- filled and blood filled cysts that grow with each menstrual cycle, and eventually turn into chocolate cysts , blisters and scars. When it implants in ovaries, it decreases egg reserve in ovaries.

2.Defective Transport :

When fallopian tubes are blocked, eggs are not able to move from the ovaries to tubes and sperm is not able to reach the egg for fertilization

Defective transport of ovum and sperm can occur because of the following:

A)Ovum: Occurrence of Pelvic Inflammatory Disease (PID), gonorrhea, peritonitis, previous tubal surgery, fimbrial adhesions, and scars of endometriosis block the passage of the egg through the fallopian tubes by kinking of tubes ; as a result the egg is not released or trapped, therefore, delaying conception.

B) Scar tissue: After abdominal surgeries, presence of scar tissue and intra abdominal adhesions may alter the relation of the ovaries, fallopian tubes, and uterus, resulting in infertility.

C)Sperm: Presence of psychosexual problems such as vaginismus and dyspareunia are more common in 20-24 years aged females and may hinder fertilization.

D)Cervical factor: Trauma, surgery, antisperm antibodies , cervical mucus may also delay pregnancy.
E) Uterine fibroids: Benign growths that appear within and around the wall of the uterus. Most women conceive easily despite having fibroids. However, some women with fibroids may not be able to get pregnant naturally or may have multiple miscarriages or preterm labour and need treatment for the same.
G) Polyps: Noncancerous growths on the lining of the uterus in the cavity. They interfere with the function of the uterus and make it difficult for a woman to get pregnant and to remain pregnant after conception and thus leading to female infertility.

3.Defective Implantation:

It occurs because of the following causes:
A) Congenital anomalies and fibroids: Anomalies such as unicornuate or bicornuate uterus, fibroids near uterine lining(endometrium), near fallopian tubes or cervix may alter implantation of blastocyst and cause infertility.

B) Genetic defects in the embryo

C) Thin endometrium

D) Endometriosis

F) Progesterone resistance or deficiency

G) Scar tissue or adhesions in the endometrial cavity from previous injuries, infections, or surgery may increase the risk of miscarriage and may interfere with implantation, thus leading to female infertility.

4.Autoimmune Disorders:

Autoimmune disorder can cause, ovarian failure, testicular failure, implantation failure, and pregnancy loss. Inflammation of blood vessels associated with other conditions such as systemic lupus erythematosus and diabetes mellitus can cause infertility. Autoantibodies such as anti-phospholipid, anti-thyroid, or antinuclear antibodies can directly associated with infertility.

So, in nutshell, if at all you think that you are having a difficulty getting pregnant or having frequent pregnancy loss, do visit your doctor at the earliest and find the CAUSE.