A natural pregnancy cannot occur if ovulation does not occur. Failure of the woman to ovulate is the cause in about 30% of couples with infertility. In some women this is a permanent problem, whilst others may experience only intermittent or temporary loss of ovulation.
Anovulation affects 6-15% of women of childbearing age.
Anovulation (a failure to ovulate) is a condition that affects between 6% and 15% of all women of childbearing age. It is a disorder of the menstrual cycle, in which a woman does not release an egg for fertilization every month. More Science...
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 ]
Symptoms can be difficult to recognize.
Because women rarely experience any overt signs of ovulation, the symptoms of anovulation can sometimes be difficult to recognize. However, there are a few symptoms that may indicate a woman is suffering from the condition. These symptoms include:
Anovulation results from a hormonal imbalance.
Anovulation is usually the result of hormonal imbalances within the body. Hormones, including estrogen and progesterone, help to trigger the body's reproductive cycle, including ovulation and menstruation. Without the proper levels of these hormones, the reproductive system can be thrown off course, preventing the ovaries from releasing an egg every month.
Around 10-15% of all cases of anovulation can be caused by a functional problem. Functional problems include a failure of the ovaries(5% of cases) and luteinised unruptured follicle syndrome (LUFS). In LUFS, the egg may have matured properly, but the follicle may have failed to burst (or the follicle may have burst without releasing the egg). Patients who are suffering from polycystic ovary syndrome, or PCOS are at risk of suffering from LUFS. More Science...
Hormonal imbalances that lead to problems with ovulation can be categorized into three main areas:
Failure to produce mature eggs
Diagnosis is by blood test and/or ultrasound.
Doctors will often advise women to record their daily Basal Body Temperature for a period of up to a month or more to assist in diagnosis. Irregular or abnormal measurements may indicate that ovulation is not taking place when it should. A series of blood tests will be used to measure the levels of those hormones that play a specific role in the ovulatory process, including:
Doctors may also perform a pelvic examination and an ultrasound. A pelvic examination involves manual palpation of the abdomen to check the size and shape of the uterus, ovaries, and fallopian tubes. An ultrasound may be used to analyze the reproductive organs. More Science...
Treatment should focus on the underlying cause.
It is important that the underlying cause of anovulation be treated, in order to restore proper ovulation. Lifestyle factors such as nutrition, stress, and exercise, may be contributing to
any hormone imbalance, and these factors must be assessed during proper treatment. Easing up on exercising or eating a healthy balanced diet can go a long way to helping treat anovulation in
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 ]
Causes of Ovulation Failure
Early (premature) menopause.
As women age they have a greater likelihood of ovarian failure. Over time, women begin to run out of eggs a few years before total menopause begins. Due to the fact that doctors cannot create new eggs, this is not a condition that can be fixed. Women desiring pregnancy may still achieve it by using donor eggs if their own aren’t viable. More Science...
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
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.
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 ]
Polycystic ovary syndrome (PCOS).
PCOS often leads to very irregular menstrual cycles and tends to be caused by the body producing higher than normal levels of androgens. These are often called “male” hormones, though women produce them in small amounts. When present in higher amounts, androgens affect ability for women to ovulate in a predictable fashion, which means periods may be irregular or sometimes even completely absent. More Science...
Being very underweight or overweight.
One of the most common causes of ovulation failure is weight loss. This loss of weight does not have to be severe, as in patients with anorexia nervosa. Even a small amount of weight loss (around one stone) may be enough to stop ovulation.
Obesity has also been shown to be a cause of anovulation. Women who are overweight can suffer from hormonal imbalances which can stop ovulation. More Science...
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.
Excessive exercise such as regular marathon running can affect a woman's hormone balance which can affect ovulation. More Science...
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 ]
Chronic (long-term) illnesses.
Several conditions can cause women to stop ovulating and skip their regular menstrual periods. These conditions include depression, obesity, thyroid malfunction, pituitary tumors and obesity. Chronic health problems, such as colitis, cystic fibrosis and kidney failure, can also affect a woman's ability to conceive. More Science...
Excessive smoking can be a cause. More Science...
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 ]
Side effects from some drugs and medications.
A side-effect from some medicines is a rare cause. Medicines that sometimes cause this include anti-inflammatory painkillers and some chemotherapy medicines. Some street drugs such as cannabis and cocaine can also affect a woman's ability to ovulate. More Science...
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 ]