There are a couple of conditions that predispose a woman to forming a luteoma during pregnancy. Polycystic Ovary Syndrome is one such condition. This syndrome is associated with high hormone levels and the failure of the ovaries to release an egg during the menstrual cycle, a symptom more often associated with menopause. The high levels of hormones in polycystic ovary syndrome seem to predispose women to forming a luteoma during pregnancy. A characteristic of luteomas is that they grow better in the presence of high levels of hormones that function in normal growth, sexual development, and reproductive function. Polycystic Ovary Syndrome causes an excess of hormones in the body including some of the hormones related to these functions. Women who have already had a luteoma during a previous pregnancy have a higher high risk of having another luteoma. In this situation, women can be counseled on the risks of another pregnancy and their alternatives. Other risk factors associated with luteomas are multiple pregnancies, advanced maternal age, and Afro-Caribbean ethnicity.

The prevalence of PCOS depends on the choice of diagnostic criteria. The World Health Organization estimates that it affects 116 million women worldwide as of 2010 (3.4% of women). One community-based prevalence study using the Rotterdam criteria found that about 18% of women had PCOS, and that 70% of them were previously undiagnosed.

Ultrasonographic findings of polycystic ovaries are found in 8–25% of normal women. 14% women on oral contraceptives are found to have polycystic ovaries. Ovarian cysts are also a common side effect of intrauterine devices (IUDs).

The incidence of ovarian remnant syndrome is difficult to determine. The available data are limited to case reports or to retrospective case series. The best available data are from a study describing the frequency and outcome of laparoscopy in women with chronic pelvic pain and/or a pelvic mass who were found to have ovarian remnants. In 119 women who underwent hysterectomy and oophorectomy by laparoscopy, ovarian remnants were known in 5 and were found during surgery in 21 patients (18%).[2] However, this was a small study and the participants were only symptomatic women. Therefore, it is not known whether the data can be extrapolated to include all women who have undergone oophorectomy.

Ovarian diseases can be classified as endocrine disorders or as a disorders of the reproductive system.

If the egg fails to release from the follicle in the ovary an ovarian cyst may form. Small ovarian cysts are common in healthy women. Some women have more follicles than usual (polycystic ovary syndrome), which inhibits the follicles to grow normally and this will cause cycle irregularities.

Other conditions include:

- Ovarian cancer

- Luteoma

- Hypogonadism

- Hyperthecosis

Sporadic OHSS is very rare, and may have a genetic component. Clomifene citrate therapy can occasionally lead to OHSS, but the vast majority of cases develop after use of gonadotropin therapy (with administration of FSH), such as Pergonal, and administration of hCG to induce final oocyte maturation and/or trigger oocyte release, often in conjunction with IVF. The frequency varies and depends on a woman's risk factors, management, and methods of surveillance. About 5% of treated women may encounter moderate to severe OHSS. Risk factors include young age, the development of many ovarian follicles under stimulation, extreme elevated serum estradiol concentrations, the use of hCG for final oocyte maturation and/or release, the continued use of hCG for luteal support, and the occurrence of a pregnancy (resulting in hCG production).

Mortality is low, but several fatal cases have been reported.

Ovarian cancer is related to the amount of time spent ovulating. Thus not having children is a risk factor for ovarian cancer, likely because ovulation is suppressed via pregnancy. During ovulation, cells are constantly stimulated to divide while ovulatory cycles continue. Therefore, people who have not borne children are at twice the risk of ovarian cancer than those who have. A longer period of ovulation caused by early first menstruation and late menopause is also a risk factor. Both obesity and hormone replacement therapy also raise the risk.

The risk of developing ovarian cancer is less for women who have fewer menstrual cycles, no menstrual cycles, breast feeding, take oral contraceptives, have multiple pregnancies, and have a pregnancy at an early age. The risk of developing ovarian cancer is reduced in women who have had tubal ligation (colloquially known as having one's "tubes tied"), both ovaries removed, or hysterectomy (an operation in which the uterus, and sometimes the cervix, is removed). Age is also a risk factor.

A diagnosis of PCOS suggests an increased risk of the following:

- Endometrial hyperplasia and endometrial cancer (cancer of the uterine lining) are possible, due to overaccumulation of uterine lining, and also lack of progesterone resulting in prolonged stimulation of uterine cells by estrogen. It is not clear whether this risk is directly due to the syndrome or from the associated obesity, hyperinsulinemia, and hyperandrogenism.

- Insulin resistance/Type II diabetes. A review published in 2010 concluded that women with PCOS have an elevated prevalence of insulin resistance and type II diabetes, even when controlling for body mass index (BMI). PCOS also makes a woman, particularly if obese, prone to gestational diabetes.

- High blood pressure, in particular if obese or during pregnancy

- Depression and anxiety

- Dyslipidemia – disorders of lipid metabolism — cholesterol and triglycerides. Women with PCOS show a decreased removal of atherosclerosis-inducing remnants, seemingly independent of insulin resistance/Type II diabetes.

- Cardiovascular disease, with a meta-analysis estimating a 2-fold risk of arterial disease for women with PCOS relative to women without PCOS, independent of BMI.

- Strokes

- Weight gain

- Miscarriage

- Sleep apnea, particularly if obesity is present

- Non-alcoholic fatty liver disease, again particularly if obesity is present

- Acanthosis nigricans (patches of darkened skin under the arms, in the groin area, on the back of the neck)

- Autoimmune thyroiditis

Early diagnosis and treatment may reduce the risk of some of these, such as type 2 diabetes and heart disease.

The risk of ovarian cancer and breast cancer is not significantly increased overall.

Most women of reproductive age develop small cysts each month, and large cysts that cause problems occur in about 8% of women before menopause. Ovarian cysts are present in about 16% of women after menopause and if present are more likely to be cancer.

Benign ovarian cysts are common in asymptomatic premenarchal girls and found in approximately 68% of ovaries of girls 2–12 years old and in 84% of ovaries of girls 0–2 years old. Most of them are smaller than 9 mm while about 10-20% are larger macrocysts. While the smaller cysts mostly disappear within 6 months the larger ones appear to be more persistent.

Industrialized nations, with the exception of Japan, have high rates of epithelial ovarian cancer, which may be due to diet in those countries. Caucasian are at a 30–40% higher risk for ovarian cancer when compared to Black and Hispanic people, likely due to socioeconomic factors; white women tend to have fewer children and different rates of gynecologic surgeries that affect risk for ovarian cancer.

Cohort studies have found a correlation between dairy consumption and ovarian cancer, but case-control studies do not show this correlation. There is mixed evidence regarding the effect of red meat and processed meat in ovarian cancer.

Tentative evidence suggests that talc, pesticides, and herbicides increase the risk of ovarian cancer. The American Cancer Society notes that as of now, no study has been able to accurately link any single chemical in the environment, or in the human diet, directly to mutations that cause ovarian cancer.

Although no large studies showing the long term outcomes for women with hyperthecosis exist, a diagnosis of hyperthecosis may suggest an increased risk for metabolic complications of hyperlipidemia and type 2 diabetes . In postmenopausal women, hyperthecosis may also contribute to the pathogenesis of endometrial polyp, endometrial hyperplasia, and endometrioid adenocarcinoma due to the association of hyperestrinism (excess estrins in the body) and hyperthecosis. Treatment for hyperthecosis is based upon each case, but may range from pharmacological interventions to surgical.

Ovarian torsion accounts for about 3% of gynecologic emergencies. The incidence of ovarian torsion among women of all ages is 5.9 per 100,000 women, and the incidence among women of reproductive age (15–45 years) is 9.9 per 100,000 women. In 70% of cases, it is diagnosed in women between 20 and 39 years of age. The risk is greater during pregnancy and in menopause. Risk factors include increased length of the ovarian ligaments, pathologically enlarged ovaries (more than 6 cm), ovarian masses or cysts, and enlarged corpus luteum in pregnancy.

Cysts associated with hypothyroidism or other endocrine problems are managed by treating the underlying condition.

About 95% of ovarian cysts are benign, not cancerous.

Functional cysts and hemorrhagic ovarian cysts usually resolve spontaneously. However, the bigger an ovarian cyst is, the less likely it is to disappear on its own. Treatment may be required if cysts persist over several months, grow, or cause increasing pain.

Cysts that persist beyond two or three menstrual cycles, or occur in post-menopausal women, may indicate more serious disease and should be investigated through ultrasonography and laparoscopy, especially in cases where family members have had ovarian cancer. Such cysts may require surgical biopsy. Additionally, a blood test may be taken before surgery to check for elevated CA-125, a tumour marker, which is often found in increased levels in ovarian cancer, although it can also be elevated by other conditions resulting in a large number of false positives.

The etiology of hyperthecosis is unknown, however evidence suggests a possibility of genetic transmission. Hyperthecosis has been documented in familiar patterns. Insulin resistance may also play a role in the pathogenesis of hyperthecosis. Women with hyperthecosis have a significant degree of insulin resistance and insulin may stimulate the ovarian stromal androgen synthesis.

Examples of congenital abnormalities of the reproductive system include:

- Kallmann syndrome - Genetic disorder causing decreased functioning of the sex hormone-producing glands caused by a deficiency or both testes from the scrotum.

- Androgen insensitivity syndrome - A genetic disorder causing people who are genetically male (i.e. XY chromosome pair) to develop sexually as a female due to an inability to utilize androgen.

- Intersexuality - A person who has genitalia and/or other sexual traits which are not clearly male or female.

Ovarian pregnancies are rare: the vast majority of ectopic pregnancies occur in the fallopian tube; only about 0.15-3% of ectopics occur in the ovary. The incidence has been reported to be about 1:3,000 to 1:7,000 deliveries.

It is also known that disruption of the endocrine system by certain chemicals adversely affects the development of the reproductive system and can cause vaginal cancer. Many other reproductive diseases have also been link to exposure to synthetic and environmental chemicals. Common chemicals with known links to reproductive disorders include: lead, dioxins and dioxin-like compounds, styrene, toluene, BPA (Bisphenol A) and pesticides.

OHSS has been characterized by the presence of multiple luteinized cysts within the ovaries leading to ovarian enlargement and secondary complications, but that definition includes almost all women undergoing ovarian stimulation. The central feature of clinically significant OHSS is the development of vascular hyperpermeability and the resulting shift of fluids into the third space.

As hCG causes the ovary to undergo extensive luteinization, large amounts of estrogens, progesterone, and local cytokines are released. It is almost certain that vascular endothelial growth factor (VEGF) is a key substance that induces vascular hyperpermeability, making local capillaries "leaky", leading to a shift of fluids from the intravascular system to the abdominal and pleural cavity. Supraphysiologic production of VEGF from many follicles under the prolonged effect of hCG appears to be the specific key process underlying OHSS. Thus, while the woman accumulates fluid in the third space, primarily in the form of ascites, she actually becomes hypovolemic and is at risk for respiratory, circulatory (such as arterial thromboembolism since blood is now thicker), and renal problems. Women who are pregnant sustain the ovarian luteinization process through the production of hCG.

Avoiding OHSS typically requires interrupting the pathological sequence, such as avoiding the use of hCG. One alternative is to use a GnRH agonist instead of hCG. While this has been repeatedly shown to "virtually eliminate" OHSS risk, there is some controversy regarding the effect on pregnancy rates if a fresh non-donor embryo transfer is attempted, almost certainly due to a luteal phase defect. There is no dispute that the GnRH agonist trigger is effective for oocyte donors and for embryo banking (cryopreservation) cycles.

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.

The cause of ORS is the unintentional retention of ovarian tissue after the procedure to remove the ovaries. If a woman is receiving hormone replacement therapy, distinguishing from other disease process may be difficult. Other confounding conditions contributing to ORS are thick and profuse pelvic adhesions, inflammation, bleeding after surgery (peri-operative bleeding), and ovaries which are retroperitoneal, can all contribute to the unintentional preservation of ovarian fragments.

Endometrioma is the presences of endometrial tissue in and sometimes on the ovary. More broadly, endometriosis is the presence of endometrial tissue located outside the uterus. The presence of endometriosis can result in the formation of scar tissue, adhesions and an inflammatory reaction. It is a benign growth. An endometrioma is most often found in the ovary. It can also develop in the cul-de-sac (space be hind the uterus), the surface of the uterus, and between the vagina and rectum.

This accounts for around 10-15% of all cases of anovulation. The ovaries can stop working in about 5% of cases. This may be because the ovaries do not contain eggs. However, a complete blockage of the ovaries is rarely a cause of infertility. Blocked ovaries can start functioning again without a clear medical explanation. In some cases, the egg may have matured properly, but the follicle may have failed to burst (or the follicle may have burst without releasing the egg). This is called luteinised unruptured follicle syndrome (LUFS). Physical damage to the ovaries, or ovaries with multiple cysts, may affect their ability to function. This is called ovarian . Patients who are suffering from Stein-Leventhal syndrome (also referred to as polycystic ovary syndrome, or PCOS) can also suffer from anovulation. Up to 90% of cases of anovulation are caused by PCOS; this syndrome is usually hereditary.

Weight loss or anorexia can also cause hormonal imbalance, leading to irregular ovulation (dysovulation). It is possible that this mechanism evolved to protect the mother’s health. A pregnancy where the mother is weak could pose a risk to the baby’s and mother’s health. On the other hand, excess weight can also create ovarian dysfunctions. Dr Barbieri of Harvard Medical School has indicated that cases of anovulation are quite frequent in women with a BMI (body mass index) over 27 /. Unfortunately, not only does excess weight have a negative impact on ovulation itself, but also on treatment efficacy and outcomes of ART (assisted reproductive technique).

The development of an ovarian mass is related to the development of torsion. In the reproductive years, regular growth of large corpus luteal cysts are a risk factor for rotation. The mass effect of ovarian tumors is also a common cause of torsion. Torsion of the ovary usually occurs with torsion of the fallopian tube as well on their shared vascular pedicle around the broad ligament, although in rare cases the ovary rotates around the mesovarium or the fallopian tube rotates around the mesosalpinx. In 80%, torsion happens unilaterally, with slight predominance on the right.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are frequently used first in patients with pelvic pain, particularly if the diagnosis of endometriosis has not been definitively (excision and biopsy) established. The goal of directed medical treatment is to achieve an anovulatory state. Typically, this is achieved initially using hormonal contraception. This can also be accomplished with progestational agents (i.e., medroxyprogesterone acetate), danazol, gestrinone, or gonadotropin-releasing hormone agonists (GnRH), as well as other less well-known agents. These agents are generally used if oral contraceptives and NSAIDs are ineffective. GnRH can be combined with estrogen and progestogen (add-back therapy) without loss of efficacy but with fewer hypoestrogenic symptoms. These medications are often ineffective in treating endometriomas and any relief is short lived while taking the medications. Hormonal treatment has a large number of sometimes permanent side effects, such as hot flushes, loss of bone mass, deepening of voice, weight gain, and facial hair growth.

A luteoma is a tumor that occurs in the ovaries during pregnancy.

It is associated with an increase of sex hormones, primarily progesterone and testosterone. The size of the tumor can range from 1 to 25 cm in diameter, but is usually 6 to 10 cm in diameter and can grow throughout the duration of the pregnancy. However, luteomas are benign and resolve themselves after delivery. This type of tumor is rare with only about 200 documented cases; many of these cases were detected accidentally, so the actual rate of occurrence may be higher. The most obvious symptom of a luteoma is masculinization of the mother and the possible masculinization of the fetus. This occurs because of the release of testosterone by the luteoma. Testosterone is a sex hormone most abundant in men although small amounts are naturally present in women. Testosterone is responsible for the male characteristics such as deepening of the voice, growth of dark hair, and acne. While not life-threatening, the development of male characteristics associated with luteomas can cause visible changes in the mother and can have drastic effects on the formation of the fetus. Luteomas can cause the fetus to be born with an ambiguous sex, which, depending on how the parents prefer to raise the infant, may result in the parents choosing a sex for the fetus.

Luteomas can be associated with female pseudohermaphroditism.

For most women, alteration of menstrual periods is the principal indication of chronic anovulation. Ovulatory menstrual periods tend to be regular and predictable in terms of cycle length, duration and heaviness of bleeding, and other symptoms. Ovulatory periods are often accompanied by midcycle symptoms such as mittelschmerz or premenstrual symptoms. In contrast, anovulation usually manifests itself as irregularity of menstrual periods, that is, unpredictable variability of intervals, duration, or bleeding. Anovulation can also cause cessation of periods (secondary amenorrhea) or excessive bleeding (dysfunctional uterine bleeding). Mittelschmerz and premenstrual symptoms tend to be absent or reduced when a woman is anovulatory.