Ovulation disorders, meaning you ovulate infrequently or not at all, account for infertility in about 25 percent of infertile couples. These can be caused by flaws in the regulation of reproductive hormones by the hypothalamus or the pituitary gland, or by problems in the ovary itself.

• Polycystic ovary syndrome (PCOS). In PCOS, complex changes occur in the hypothalamus, pituitary gland and ovaries, resulting in a hormone imbalance, which affects ovulation. PCOS is associated with insulin resistance and obesity, abnormal hair growth on the face or body, and acne. It’s the most common cause of female infertility.Achieving pregnancy requires that your ovaries produce and release an egg, a process known as ovulation. Your doctor can help evaluate your menstrual cycles and confirm ovulation.
• Hypothalamic dysfunction The two hormones responsible for stimulating ovulation each month — follicle-stimulating hormone (FSH) and luteinizing hormone (LH) — are produced by the pituitary gland in a specific pattern during the menstrual cycle. Excess physical or emotional stress, a very high or very low body weight, or a recent substantial weight gain or loss can disrupt this pattern and affect ovulation. The main sign of this problem is irregular or absent periods.
• Premature ovarian insufficiency This disorder is usually caused by an autoimmune response where your body mistakenly attacks ovarian tissues or by premature loss of eggs from your ovary due to genetic problems or environmental insults such as chemotherapy. It results in the loss of the ability to produce eggs by the ovary, as well as a decreased estrogen production under the age of 40.
• Too much prolactin Less commonly, the pituitary gland can cause excess production of prolactin (hyperprolactinemia), which reduces estrogen production and may cause infertility. Most commonly this is due to a problem in the pituitary gland, but it can also be related to medications you’re taking for another disease.