Infertility is defines as a failure to achieve a clinical pregnancy after 12 months or more of regular unprotected sexual intercourse. The main causes for infertility are obesity, undisciplined diet, smoking, medical conditions, environmental pollutants, medications and family history. Childless can cause of marital upset as well as personal unhappiness and ill health.

Infertility can arise from either of the partners. Infertility is usually because of low numbers or poor quality of sperm in men whereas in woman, it occurs when she is not able to produce eggs regularly or because her fallopian tubes are damaged or blocked and the sperm cannot reach her eggs.

The main causes for female infertility are:

Ovulation disorders

Ovulation disorders, is a condition where ovary ovulate infrequently or not at all. Problems with the regulation of reproductive hormones by the hypothalamus or the pituitary gland, or problems in the ovary, can cause ovulation disorders.

• Polycystic ovary syndrome (PCOS). PCOS causes a hormone imbalance, which affects ovulation. PCOS is associated with insulin resistance and obesity, abnormal hair growth on the face or body, and acne. It's the most common cause of female infertility.
• Hypothalamic dysfunction. Two hormones produced by the pituitary gland are responsible for stimulating ovulation FSH and LH. Excess physical or emotional stress, a very high or very low body weight, or a recent substantial weight gain or loss can disrupt production of these hormones and affect ovulation. Irregular or absent periods are the most common signs.
• Premature ovarian failure. Also called primary ovarian insufficiency, this disorder is usually caused by an autoimmune response or by premature loss of eggs from your ovary (possibly from genetics or chemotherapy). The ovary no longer produces eggs, and it lowers estrogen production in women under the age of 40.
• Dysfunction of Pituitary gland. The pituitary gland may cause excess production of prolactin (hyperprolactinemia), which reduces estrogen production and may cause infertility. Usually related to a pituitary gland problem, this can also be caused by medications you're taking for another disease.

• Damage to fallopian tubes (tubal infertility)Damaged or blocked fallopian tubes Pelvic inflammatory disease Previous surgery in the abdomen or pelvisPelvic tuberculosis

• Endometriosis Endometriosis occurs when tissue that normally grows in the uterus implants and grows in   other locations. This extra tissue growth can cause scarring, which may block fallopian tubes and keep an egg and sperm from uniting.

• Uterine or cervical causes Several uterine or cervical causes can impact fertility by interfering with implantation or increasing the likelihood of a miscarriage like benign polyps or tumours (fibroids or myomas).

Risk factors

Certain factors may put higher risk of infertility in females, including:

• Age.
•  Smoking.
• Obesity.
•  Alcohol

Male - due to following reasons

More than 90% of male infertility cases are due to low sperm counts, poor sperm quality, or both. The remaining cases of male infertility can be caused by a range of conditions including anatomical problems, hormonal imbalances, and genetic defects.

Sperm Abnormalities

Sperm abnormalities are a critical factor in male infertility. These abnormalities include:

• Low sperm count
• Poor sperm motility (movement)
• Abnormal sperm shape

Risk Factors

Risk factors for male infertility include:

• Varicocele, an enlarged varicose vein in the spermatic cord that connects to the testicle
• Aging, which can reduce sperm counts and motility and decrease the genetic quality of sperm
• Lifestyle factors such as smoking and substance abuse
• Long-term or intensive exposure to certain types of chemicals, toxins, or medications
• Undescended testicles
• Diabetes