Conception occurs after an egg has been fertilized with a sperm cell. The “fertile window” is only six days long, starting around five days before ovulation and ending the day after ovulation.
Ovulation involves the release of the egg during the monthly menstrual cycle. Problems that affect ovulation are the most common cause of infertility. These include:
Polycystic ovarian syndrome (PCOS) – Women with PCOS do not regularly ovulate, and they also experience infrequent of absent menstrual cycles. With PCOS, the ovaries produce excessive androgens (male hormones), which causes high levels of luteinizing hormone (LH) and low levels of follicle-stimulating hormone (FSH). These hormone imbalances prevent the ovarian follicles from producing a mature egg, which causes the follicles to swell with fluid. Elevated levels of androgens also cause obesity, acne, and facial hair.
Premature ovarian failure (POF) – Early menopause is the depletion of ovarian follicles before the age of 40 years. This leads to premature menopause, and cases hormonal issues, such as thyroid, adrenal, and pituitary deficiencies. POF can also be due to genetic disorders, such as fragile X syndrome and Turner syndrome.
Hormone imbalances – Anything that interferes with the production of reproductive hormones (progesterone, estrogen, FSH, and/or LH) can affect ovulation.
Blocked Fallopian Tubes
One or more blocked fallopian tubes can prevent sperm from reaching the egg for fertilization. Blockage of the fallopian tubes will prevent a fertilized egg from moving to the uterus for implantation. Conditions that will damage or block the fallopian tubes are:
Endometriosis – Cells that line the uterus can grow in other areas, such as the fallopian tubes, ovaries, and pelvic cavity. Endometrial implants will block the egg from passing along the fallopian tube, or it may block the ovaries from releasing the egg. Severe bands of adhesions (scar tissue) between the ovaries, uterus, and fallopian tubes prevent egg transfer.
Pelvic inflammatory disease (PID) – This condition is infection of the reproductive tract, including the tubes. This condition occurs from chlamydia, gonorrhea, and bacterial infections.
Any condition that affects the uterus will lead to infertility. These conditions include:
Uterine scarring – Adhesions caused by endometriosis or pelvic surgery can affect the function of the uterus and make it difficult to carry a pregnancy to term.
Uterine fibroids – Fibroids are growths that contribute to infertility by blocking the fallopian tubes or altering the shape of the uterine cavity. Fibroids also alter blood flow to the lining of the uterus.
Other Causes of Female Infertility
Elevated prolactin levels – Prolactin is a hormone produce by the pituitary gland. High levels of prolactin will reduce gonadotropin hormones, which inhibits ovulation. Excessive prolactin can be caused by a pituitary growth or underactive thyroid gland.
Congenital structural abnormalities – Abnormalities of the reproductive tract are often formed before birth. Daughters of women who took diethylstilbestrol (DES) during pregnancy are at risk for fallopian tube and uterine structural abnormalities.
Egg quality – As a woman ages, the quality and number of eggs diminish. Younger women also have problems related to egg quality, because many medical conditions and clinical treatments impair the ovaries.
Weight – Being overweight will contribute to infertility because estrogen is produced by fat cells. Women who are underweight do not produce adequate hormones, including women with eating disorders, strict vegetarians, and women on restricted diets.