Clomifene citrate (or clomid) is the medication which is most commonly used to treat anovulation. It is a selective estrogen-receptor modulator, affecting the hypothalamic–pituitary–gonadal axis to respond as if there was an estrogen deficit in the body, in effect increasing the production of gonadotrophins. It is relatively easy and convenient to use. Clomifene appears to inhibit estrogen receptors in hypothalamus, thereby inhibiting negative feedback of estrogen on gonadotrophin production. It may also result in direct stimulation of the hypothalamic-pituitary axis. It also has an 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.

The standard dosage for first-time takers is 50 or 100 mg of clomifene per day for five consecutive days, starting early in the menstrual cycle, usually on the third to fifth day counting from the beginning of the menstrual period. In case of amenorrhea, a period can be induced by intake of an oral progestin for 10 days. In absence of success, the dosage can be increased in subsequent cycles with increments of 50 mg. However, at a dosage of 200 mg, further increments are unlikely to increase pregnancy chances.

The European Society of Human Reproduction and Embryology (ESHRE) notes that the aim of ovulation induction should be mono-ovulation and not over-stimulation of the ovaries . The risks associated with multiple pregnancy are much higher than singleton pregnancy; incidences of perinatal death are seven times higher in triplet births and five times higher in twin births than the risks associated with a singleton pregnancy. It is therefore important to adapt the treatment to each individual patient.

Women with polycystic ovary syndrome may be particularly at risk. Multiple pregnancy occurs in approximately 15-20% of cases following cycles induced with gonadotrophins such as hMG and FSH induced ovulations.

During ovulation induction, it is recommended to start at a low dose and monitor the ovarian response with vaginal ultrasound, including discernment of the number of developing follicles. A cycle with supernumerary follicles is usually defined as one where there are more than two follicles >16 mm in diameter. It is generally recommended to have such cycles cancelled because of the risk of multiple pregnancy. In cancelled cycles, the woman or couple should be warned of the risks in case of supernumerary follicles, and should avoid sexual intercourse or use contraception until the next menstruation. Induction of final maturation (such as done with hCG) may need to be withheld because of increased risk of ovarian hyperstimulation syndrome(OHSS). The starting dose of the inducing drug should be reduced in the next cycle.

Alternatives to cancelling a cycle are mainly:

- Aspiration of supernumerary follicles until one or two remain.

- Converting the protocol to IVF treatment with embryo transfer of up to two embryos only.

- Selective fetal reduction. This alternative confers a high risk of complications.

- Proceeding with any multiple pregnancy without fetal reduction, with the ensuing risk of complications. This alternative is not recommended.

In the context of the menopause, hormone replacement therapy (HRT) is the use of estrogen in women without a uterus and estrogen plus progestin in women who have an intact uterus.

HRT may be reasonable for the treatment of menopausal symptoms, such as hot flashes. It is the most effective treatment option, especially when delivered as a skin patch. Its use, however, appears to increase the risk of strokes and blood clots. When used for menopausal symptoms some recommend it be used for the shortest time possible and at the lowest dose possible. Evidence to support long term use however is poor.

It also appears effective for preventing bone loss and osteoporotic fracture, but it is generally recommended only for women at significant risk for whom other therapies are unsuitable.

HRT may be unsuitable for some women, including those at increased risk of cardiovascular disease, increased risk of thromboembolic disease (such as those with obesity or a history of venous thrombosis) or increased risk of some types of cancer. There is some concern that this treatment increases the risk of breast cancer.

Adding testosterone to hormone therapy has a positive effect on sexual function in postmenopausal women, although it may be accompanied by hair growth, acne and a reduction in high-density lipoprotein (HDL) cholesterol. These side effects diverge depending on the doses and methods of using testosterone.

Certain medications, particularly contraceptive medications, can induce amenorrhoea in a healthy woman. The lack of menstruation usually begins shortly after beginning the medication and can take up to a year to resume after stopping a medication. Hormonal contraceptives that contain only progestogen like the oral contraceptive Micronor, and especially higher-dose formulations like the injectable Depo Provera commonly induce this side-effect. Extended cycle use of combined hormonal contraceptives also allow suppression of menstruation. Patients who use and then cease using contraceptives like the combined oral contraceptive pill may experience secondary amenorrhoea as a withdrawal symptom. The link is not well understood, as studies have found no difference in hormone levels between women who develop amenorrhoea as a withdrawal symptom following the cessation of OCOP use and women who experience secondary amenorrhoea because of other reasons. New contraceptive pills, like continuous oral contraceptive pills (OCPs) which do not have the normal 7 days of placebo pills in each cycle, have been shown to increase rates of amenorrhoea in women. Studies show that women are most likely to experience amenorrhoea after 1 year of treatment with continuous OCP use.

The use of opiates (such as heroin) on a regular basis has also been known to cause amenorrhoea in longer term users.

Anti-psychotic drugs used to treat schizophrenia have been known to cause amenorrhoea as well. New research suggests that adding a dosage of Metformin to an anti-psychotic drug regimen can restore menstruation. Metformin decreases resistance to the hormone insulin, as well as levels of prolactin, testosterone, and lutenizing hormone (LH). Metformin also decreases the LH/FSH ratio. Results of the study on Metformin further implicate the regulation of these hormones as a main cause of secondary amenorrhoea.

SERMs are a category of drugs, either synthetically produced or derived from a botanical source, that act selectively as agonists or antagonists on the estrogen receptors throughout the body. The most commonly prescribed SERMs are raloxifene and tamoxifen. Raloxifene exhibits oestrogen agonist activity on bone and lipids, and antagonist activity on breast and the endometrium. Tamoxifen is in widespread use for treatment of hormone sensitive breast cancer. Raloxifene prevents vertebral fractures in postmenopausal, osteoporotic women and reduces the risk of invasive breast cancer.

Breastfeeding is a common cause of secondary amenorrhoea, and often the condition lasts for over six months. Breastfeeding typically lasts longer than lactational amenorrhoea, and the duration of amenorrhoea varies depending on how often a women breastfeeds. Lactational amenorrhoea has been advocated as a method of family planning, especially in developing countries where access to other methods of contraception may be limited. Breastfeeding is said to prevent more births in the developing world than any other method of birth control or contraception. Lactational amenorrhoea is 98% percent effective as a method of preventing pregnancy in the first six months postpartum.

There is insufficient evidence to recommend the use of any herbal or dietary supplements for treating dysmenorrhea, including, melatonin, vitamin E, fennel, dill, chamomile, cinnamon, damask rose, rhubarb, guava, and uzara. Further research is recommended to follow up on weak evidence of benefit for: fenugreek, ginger, valerian, zataria, zinc sulphate, fish oil, and vitamin B1. A 2016 review found that evidence of safety is insufficient for all dietary supplements.

There is some conflicting evidence in the scientific literature, including:

One review found thiamine and vitamin E to be likely effective. It found the effects of fish oil and vitamin B12 to be unknown.

Reviews found tentative evidence that ginger powder may be effective for primary dysmenorrhea.

Another review found Vitamin B1 to be effective. Magnesium supplementation are a promising possible treatment.

Reviews have found promising evidence for Chinese herbal medicine for primary dysmenorrhea, but that the evidence was limited by its poor methodological quality.

Acupuncture: A 2016 Cochrane review found that the randomized controlled trials (RCTs) of acupuncture treatments for dysmenorrhea are of low quality and concluded that it is unknown if acupuncture or acupressure is effective for treating symptoms of primary dysmenorrhea. There are also concerns of bias in study design and in publication, insufficient reporting (few looked at adverse effects), and that they were inconsistent. There are conflicting reports in the literature, including one review which found that acupressure, topical heat, transcutaneous electrical nerve stimulation, and behavioral interventions are likely effective. It found the effect of acupuncture and magnets to be unknown.

A 2007 systematic review found some scientific evidence that behavioral interventions may be effective, but that the results should be viewed with caution due to poor quality of the data.

Spinal manipulation does not appear to be helpful. Although claims have been made for chiropractic care, under the theory that treating subluxations in the spine may decrease symptoms, a 2006 systematic review found that overall no evidence suggests that spinal manipulation is effective for treatment of primary and secondary dysmenorrhea.

Drug of choice is progesterone.

Management of dysfunctional uterine bleeding predominantly consists of reassurance, though mid-cycle estrogen and late-cycle progestin can be used for mid- and late-cycle bleeding respectively.

Also, non-specific hormonal therapy such as combined high-dose estrogen and high-dose progestin can be given. Ormeloxifene is a non-hormonal medication that treats DUB but is only legally available in India.

The goal of therapy should be to arrest bleeding, replace lost iron to avoid anemia, and prevent future bleeding.

Excessive movement before any treatments or surgeries will cause excessive bleeding.

A hysterectomy may be performed in some cases.

A menstrual disorder is an abnormal condition in a woman's menstrual cycle.

Irregular menstruation is a menstrual disorder whose manifestations include irregular cycle lengths as well as metrorrhagia (vaginal bleeding between expected periods).

Exercise amenorrhoea can be managed by eating a diet rich in calories and by decreasing the duration and intensity of exercise for at least 12 months. Amenorrhea usually persists and may take over 6 months to reverse .

Not all women with PCOS have difficulty becoming pregnant. For those that do, anovulation or infrequent ovulation is a common cause. Other factors include changed levels of gonadotropins, hyperandrogenemia and hyperinsulinemia. Like women without PCOS, women with PCOS that are ovulating may be infertile due to other causes, such as tubal blockages due to a history of sexually transmitted diseases.

For overweight, anovulatory women with PCOS, weight loss and diet adjustments, especially to reduce the intake of simple carbohydrates, are associated with resumption of natural ovulation.

For those women that after weight loss still are anovulatory or for anovulatory lean women, then the ovulation-inducing medications clomiphene citrate and FSH are the principal treatments used to promote ovulation. Previously, the anti-diabetes medication metformin was recommended treatment for anovulation, but it appears less effective than clomiphene.

For women not responsive to clomiphene and diet and lifestyle modification, there are options available including assisted reproductive technology procedures such as controlled ovarian hyperstimulation with follicle-stimulating hormone (FSH) injections followed by in vitro fertilisation (IVF).

Though surgery is not commonly performed, the polycystic ovaries can be treated with a laparoscopic procedure called "ovarian drilling" (puncture of 4–10 small follicles with electrocautery, laser, or biopsy needles), which often results in either resumption of spontaneous ovulations or ovulations after adjuvant treatment with clomiphene or FSH. (Ovarian wedge resection is no longer used as much due to complications such as adhesions and the presence of frequently effective medications.) There are, however, concerns about the long-term effects of ovarian drilling on ovarian function.

Surgery is more effective than medicinal intervention for addressing infertility associated with endometriosis. Surgery attempts to remove endometrial tissue and preserve the ovaries without damaging normal tissue. In-vitro fertilization (IVF) procedures are effective in improving fertility in many women with endometriosis.

Dysmenorrhea (or dysmenorrhoea), cramps or painful menstruation, involves menstrual periods that are accompanied by either sharp, intermittent pain or dull, aching pain, usually in the pelvis or lower abdomen.

Limited evidence indicates that the use of combined oral contraceptives is associated with a reduced risk of endometriosis.

Medications for PCOS include oral contraceptives and metformin. The oral contraceptives increase sex hormone binding globulin production, which increases binding of free testosterone. This reduces the symptoms of hirsutism caused by high testosterone and regulates return to normal menstrual periods. Metformin is a drug commonly used in type 2 diabetes to reduce insulin resistance, and is used off label (in the UK, US, AU and EU) to treat insulin resistance seen in PCOS. In many cases, metformin also supports ovarian function and return to normal ovulation. Spironolactone can be used for its antiandrogenic effects, and the topical cream eflornithine can be used to reduce facial hair. A newer insulin resistance drug class, the thiazolidinediones (glitazones), have shown equivalent efficacy to metformin, but metformin has a more favorable side effect profile. The United Kingdom's National Institute for Health and Clinical Excellence recommended in 2004 that women with PCOS and a body mass index above 25 be given metformin when other therapy has failed to produce results. Metformin may not be effective in every type of PCOS, and therefore there is some disagreement about whether it should be used as a general first line therapy. The use of statins in the management of underlying metabolic syndrome remains unclear.

It can be difficult to become pregnant with PCOS because it causes irregular ovulation. Medications to induce fertility when trying to conceive include the ovulation inducer clomiphene or pulsatile leuprolide. Metformin improves the efficacy of fertility treatment when used in combination with clomiphene. Metformin is thought to be safe to use during pregnancy (pregnancy category B in the US). A review in 2014 concluded that the use of metformin does not increase the risk of major birth defects in women treated with metformin during the first trimester.

Oligomenorrhea (or oligomenorrhoea) is infrequent (or, in occasional usage, very light) menstruation. More strictly, it is menstrual periods occurring at intervals of greater than 35 days, with only four to nine periods in a year. Menstrual periods should have been regularly established before the development of infrequent flow. The duration of such events may vary.

Irregular cycles or irregular periods is an abnormal variation in length of menstrual cycles. A female usually experiences cycle length variations of up to eight days between the shortest and longest cycle lengths. Lengths ranging between eight and 20 days are considered moderately irregular. Variation of 21 days or more is considered very irregular.

Alternatively, a single menstruation period may be defined as irregular if it is shorter than 21 days or longer than 36 days. If they are regularly shorter than 21 days or longer than 36 (or 35) days, the condition is termed polymenorrhea or oligomenorrhea, respectively.

Oligomenorrhea can be a result of prolactinomas (adenomas of the anterior pituitary). It may be caused by thyrotoxicosis, hormonal changes in perimenopause, Prader–Willi syndrome, and Graves disease.

"Endurance exercises such as running or swimming can affect the reproductive physiology of women athletes. Female runners, swimmers and ballet dancers menstruate infrequently in comparison to nonatheletic women of comparable age or not at all (amenorrhea). The degree of menstrual abnormality is directly proportional to the intensity of the exercise. For example, Malina et al., (1978) have shown menstrual irregularity is more common, and more severe among tennis players than among golfers" (modified by a student paper written by A. Lord)

Breastfeeding has been linked to irregularity of menstrual cycles due to hormones that delay ovulation.

Women with polycystic ovary syndrome (PCOS) are also likely to suffer from oligomenorrhea. PCOS is a condition in which excessive androgens (male sex hormones) are released by the ovaries. Women with PCOS show menstrual irregularities that range from oligomenorrhea and amenorrhea, to very heavy, irregular periods. The condition affects about 6% of premenopausal women.

Eating disorders can result in oligomenorrhea. Although menstrual disorders are most strongly associated with Anorexia nervosa, Bulimia nervosa may also result in oligomenorrhea or amenorrhea. There is some controversy regarding the mechanism for the menstrual dysregulation, since amenorrhea may sometimes precede substantial weight loss in some anorexics. Some researchers hypothesize that some as-yet unrecognized neuroendocrine phenomenon may be involved; the menstrual irregularities may be related to the biological undergirding of the disorders, rather than a result of nutritional deficiencies.

Excessive menstruation between puberty and 19 years of age is called puberty menorrhagia. Excessive menstruation is defined as bleeding over 80 ml per menstrual period or lasting more than 7 days. The most common cause for puberty menorrhagia is dysfunctional uterine bleeding. The other reasons are idiopathic thrombocytopenic purpura, hypothyroidism, genital tuberculosis, polycystic ovarian disease, leukemia and coagulation disorders. The most common physiological reason for puberty menorrhagia is the immaturity of hypothalamic-pituitary-ovarian axis, leading to inadequate positive feedback and sustained high estrogen levels. Most patients present with anemia due to excessive blood loss.

The patient is assessed with a thorough medical history, physical examination (to look for features of anemia), gynaecological examination (to rule out local causes) and laboratory investigations (to rule out coagulopathies and malignancy). It is mandatory to exclude pregnancy. The treatment is determined based on the cause of menorrhagia. In case of puberty menorrhagia due to immaturity of hypothalamic axis, hormonal therapy is beneficial. Treatment for blood loss should be done simultaneously with iron therapy in mild to moderate blood loss and blood transfusion in severe blood loss.

One possible treatment is with anastrozole. Histrelin acetate (Supprelin LA), triptorelin or leuprolide, any GnRH agonists, may be used. Non-continuous usage of GnRH agonists stimulates the pituitary gland to release follicle stimulating hormone (FSH) and luteinizing hormone (LH). However, when used regularly, GnRH agonists cause a decreased release of FSH and LH. Prolonged use has a risk of causing osteoporosis. After stopping GnRH agonists, pubertal changes resume within 3 to 12 months.

10% of cases occur in women who are ovulating, but progesterone secretion is prolonged because estrogen levels are low. This causes irregular shedding of the uterine lining and break-through bleeding. Some evidence has associated Ovulatory DUB with more fragile blood vessels in the uterus.

It may represent a possible endocrine dysfunction, resulting in menorrhagia or metrorrhagia.

Mid-cycle bleeding may indicate a transient estrogen decline, while late-cycle bleeding may indicate progesterone deficiency.

The fertility drug clomiphene citrate (Clomid, Serophene), used to induce ovulation, increases the risk of a corpus luteum cyst developing after ovulation. These cysts don't prevent or threaten a resulting pregnancy. Women on birth control pills usually do not form these cysts; in fact, preventing these cysts is one way birth control pills work.

In contrast, the progesterone-only pill can cause increased frequency of these cysts.

Exercise induced amenorrhoea occurs in 5-25% of athletes and 1.8% of the general population. The incidence is higher in marathon runners and is more frequent in women who weigh less and were slightly younger . Exercise amenorrhoea has also been reported in ballet dancers, cyclists, swimmers and those involved in non-weight bearing sports .