An anovulatory cycle is a menstrual cycle during which the ovaries do not release an oocyte. Therefore, ovulation does not take place. However, a woman who does not ovulate at each menstrual cycle is not necessarily going through menopause. Chronic anovulation is a common cause of infertility. [ x ]

No science just yet... [ x ]

Hormonal imbalances that lead to problems with ovulation can be categorized into three main areas:

Failure to produce mature eggs
In approximately 50% of the cases of anovulation, the ovaries do not produce normal follicles in which the eggs can mature.  Ovulation is rare if the eggs are immature and the chance of fertilization becomes almost nonexistent.  Polycystic ovary syndrome, the most common disorder responsible for this problem, includes symptoms such as amenorrhoea, hirsutism, anovulation and infertility.  This syndrome is characterized by a reduced production of FSH, and normal or increased levels of LH, oestrogen and testosterone.  The current hypothesis is that the suppression of FSH associated with this condition causes only partial development of ovarian follicles, and follicular cysts can be detected in an ultrasound scan.  The affected ovary often becomes surrounded with a smooth white capsule and is double its normal size.
    
Malfunction of the hypothalamus
The hypothalamus is the portion of the brain responsible for sending signals to the pituitary gland, which, in turn, sends hormonal stimuli to the ovaries in the form of FSH and LH to initiate egg maturation.  If the hypothalamus fails to trigger and control this process, immature eggs will result.  This is the cause of ovarian failure in 20% of cases.
    
Malfunction of the pituitary gland
The pituitary's responsibility lies in producing and secreting FSH and LH.  The ovaries will be unable to ovulate properly if either too much or too little of these substances is produced.  This can occur due to physical injury, a tumor or if there is a chemical imbalance in the pituitary. [ x ]

No science just yet... [ x ]

The medication which is most commonly used to treat anovulation is clomifene citrate (or clomid).  Administered in pill form, Clomifene appears to inhibit estrogen receptors in the hypothalamus, thereby inhibiting negative feedback of estrogen on gonadotropin production.  It may also result in direct stimulation of the hypothalamic-pituitary axis.  Undesired consequences include a detrimental effect on cervical mucus quality and uterine mucosa, which might affect sperm penetration and survival, hence its early administration during the menstrual cycle.

Clomifene citrate is a very efficient ovulation inductor, and has a success rate of 67%. Nevertheless, it only has a 37% success rate in inducing pregnancy. This difference may be due to the anti-estrogenic effect which clomifene citrate has on the endometrium, cervical mucus, uterine blood flow, as well as the resulting decrease in the motility of the fallopian tubes and the maturation of the oocytes. [ x ]

In women with normal ovarian function, the pituitary gland releases certain hormones during the menstrual cycle, which causes a small number of egg-containing follicles in the ovaries to begin maturing.  Usually, only one follicle reaches maturity, releasing an egg each month.  The egg then enters the fallopian tube, where a sperm cell might fertilize it, resulting in pregnancy.

Premature ovarian failure can result from either follicle depletion or follicle dysfunction:

Follicle Depletion 

Follicle depletion can be caused by genetic disorders and toxins.  These include Turner's syndrome, a condition in which a woman has only one X chromosome instead of the usual two, and fragile X syndrome, a major cause of mental retardation.

Chemotherapy and radiation therapy treatments are the most common causes of toxin-induced ovarian failure.  Other toxins such as cigarette smoke, chemicals, pesticides and viruses may hasten ovarian failure.

Follicle Dysfunction

Whilst, follicle dysfunction may be the result of an immune-system response to ovarian tissue, the exact cause often remains unknown.  In an auto-immune disease, a woman's immune system may produce antibodies against her own ovarian tissue, harming the egg-containing follicles and damaging the egg. What triggers the immune response is unclear, but exposure to a virus is one possibility. [ x ]

No science just yet... [ x ]

A study published in Human Reproduction looked at whether Weight loss in obese infertile women could improve their fertility.  The study used a weight loss programme to determine whether it could help obese infertile women, irrespective of their infertility diagnosis, to achieve a viable pregnancy, ideally without further medical intervention. The subjects underwent a weekly programme aimed at lifestyle changes in relation to exercise and diet for 6 months; those that did not complete the 6 months were treated as a comparison group. Women in the study lost an average of 10.2 kg/m2, with 60 of the 67 anovulatory subjects resuming spontaneous ovulation, 52 achieving a pregnancy (18 spontaneously) and 45 a live birth. The miscarriage rate was 18%, compared to 75% for the same women prior to the programme. Psychometric measurements also improved. None of these changes occurred in the comparison group.

The cost savings of the programme were considerable. Prior to the programme, the 67 women had had treatment costing a total of A$550 000 for two live births, a cost of A$275 000 per baby. After the programme, the same women had treatment costing a total of A$210 000 for 45 babies, a cost of A$4600 per baby. Thus, it was concluded that weight loss should be considered as a first option for women who are infertile and overweight.  [ x ]

Women come in all shapes and sizes and the amount of exercise that is appropriate for each woman varies.  Some women may exercise in excess of three hours per day, seven days a week and remain fertile. Others may exercise only an hour a day, three days a week and yet suffer from infertility as a result.  Exercise causes the body to produce endorphins.  These hormones produce feelings of euphoria which is also known as the 'runner's high'.  However, endorphins also increase levels of prolactin, which the body releases for the production of breast milk.  An increase in prolactin may decrease the possibility of pregnancy.  Over exercise can also interfere with other hormones responsible for regulating the female reproductive system - GnRH, LH, FSH, and estradiol are changed in ways that interfere with ovulation

Too much exercise can also cause a luteal phase defect. The luteal phase is the time period between ovulation and a woman's expected period.  A normal luteal phase is between 12 and 16 days. A shorter luteal phase can interfere with getting pregnant. [ x ]

No science just yet... [ x ]

A study published in the January 1999 edition of Obstetrics & Gynecology looked at the relationship between smoking and menstrual function.  The study looked at 408 women who collected urine daily for 1-7 menstrual cycles, maintained daily diaries, and completed detailed interviews. Smoking data from the diaries were averaged over each cycle and verified by cotinine assay. Urine samples were analyzed for metabolites of steroid hormones to define the day of ovulation and various menstrual characteristics, including: 1) cycle, follicular, luteal phase, and menses length, 2) variabililty, and 3) anovulation.

The results of the study indicated that heavy smoking (at least 20 cigarettes per day) was associated with nearly four times the risk of a short cycle length (less than 25 days) as was nonsmoking.  Mean cycle length was on average 2.6 days shorter with heavy versus no smoking, due almost entirely to shortening of the follicular phase. Women who smoked an average of ten or more cigarettes per day had significantly more variable cycles and menses lengths than nonsmokers. Based on small numbers, the data suggested that with greater smoking, there was a possible increased risk of anovulation and short luteal phase. Cycles of exsmokers with ten or more pack-years of exposure were more likely to be short and have shorter luteal phases than those of never smokers. [ x ]

Longterm use of marijuana has been found to cause physiological changes that can alter individual reproductive potential.  Longterm effects are particularly hard to assess but it is known that marijuana is absorbed rapidly and eliminated very slowly. The active principle, delta-9-tetrahidrocannabinol (delta-9-THC), is highly liposoluble and fixes to the serum proteins, passing to the lungs and liver for metabolization and to the kidneys and liver for excretion. As with estrogens, there is an enterohepatic circuit for reabsorption and elimination. 90% is eliminated in the faeces, 65% within 48 hours. Because of the enterohepatic circuit and liposolubility, elimination requires 1 week for completion. The other important biotransformation of the active principle is hydroxilation; the hydroxilated derivatives are responsible for the psychoactivity of cannabis. Cannabis affects both neuroendocrine function and the germ cells. Studies on experimental animals have indicated that THC can cause a decline in the pituitary hormones follicle stimulating hormone, luteinizing hormone, and prolactin, and in the steroids progesterone, estrogen, and androgens. Human studies have shown that chronic users have decreased levels of serum testosterone. Because steroidogenesis can be restimulated with human chorionic gonadotropin, it appears that THC does not directly affect steroid production by the corpus luteum, but that its action is mediated by the hypothalamus. Because of its potent antigonadotropic action, THC is under study as an anovulatory agent. The same animal studies have shown that ovulation returns to normal 6 months after termination of use. High rates of anovulation and luteal insufficiency have been observed in women smoking marijuana at least 3 times weekly. [ x ]