Ovulation is part of a complex series of hormonal events that begins with egg recruitment and culminates with the release of the egg from the ovarian follicle. Ovulation typically begins at puberty and ends with menopause. A female's ovary contains her entire lifetime supply of eggs at birth. The eggs develop within the ovarian follicles during each monthly menstrual cycle. Rarely, a woman is born with no ovaries and donor egg IVF is the only option for achieving pregnancy.
Each month a normally ovulating female undergoes an ovulatory cycle which includes: 1) egg recruitment and development (follicular phase) 2) ovulation- leutinizing hormone stimulates the release of the egg from the ovarian follicle 3) the luteal phase when the empty follicle (corpus luteum) secretes progesterone which stimulates the lining of the uterus to grow and divide in preparation to accept and support an embryo.
The endometrial cycle denotes the various stages of endometrial tissue (lining of the uterus) development that occurs during a complete menstrual cycle. The average menstrual cycle lasts 28 days, beginning with the first day of blood flow and ending with the first day of the next period. The menstrual cycle encompasses the events of egg recruitment, follicular development, endometrial growth, ovulation, and culminates with an implanted embryo (pregnancy), or blood flow caused by the breakdown of the endometrial tissue.
A normally ovulating female ovulates once each month. Oligoovulation refers to irregular ovulation and anovulation refers to the lack of ovulation. Similarly, amenorrhoea refers to the lack of a menstrual cycle. Ovulatory dysfunction has many causes including polycystic ovarian disease, and diseases of the pituitary, adrenal, or thyroid glands. Irregular ovulation can also be caused by excessive exercise, very low body weight, stress, breast feeding, and other conditions. Ovulation can be predicted by several methods, which is useful for timing intercourse.
Body temperature rises immediately prior to ovulation and a basal body temperature measurement (BBT Chart) can be used to signal when ovulation will occur. A BBT chart is created by measuring the resting morning (prior to getting out of bed) body temperature daily for several months and graphing the temperatures on a chart. The charts provide an "ovulation pattern" and indicate the most likely days of ovulation.
Ovulation detection kits measure the surge in leutinizing hormone that occurs immediately prior to ovulation. This method is more accurate and less troublesome; however, it is more expensive. Ovarian function is assessed using measurements of FSH, LH, estradiol, and other hormones. An elevated FSH level on day 3 is one indicator of impending ovarian failure, and the menopause. The clomiphene citrate challenge test (CCCT; see specialists discussions) is often used to determine ovarian function and predict the success of procedures such as IVF.
Clomid is often used as a first line therapy to "induce
and regulate" ovulation. Clomid has little utility
in normally ovulating women and, once ovulation is regular,
increasing the dosage does not improve pregnancy rates.
Clomid should not be used beyond three to six months. (Huntington Reproductive Clomid Web site has extensive information on Clomid.
is an injectable medication that stimulates the ovarian
follicles directly and is used in assisted reproductive
technologies. FSH is also sometimes used in intrauterine
insemination (IUI) cycles and should only be administered
by a reproductive endocrinologist. Most high order multiple
births are a result of FSH stimulated IUI cycles because
it is difficult to control the number of eggs ovulated.
FSH can produce side effects and patients must be closely
monitored by a specialist thoroughly trained in its
levels of prolactin (Hyperprolactenemia) can also cause
irregular ovulation. Prolactin stimulates milk production
in a pregnant female and this phenomenon is partly responsible
for the myth that a breast feeding female cannot become
pregnant. Hyperprolactenemia is elevated levels of prolactin
in the absence of pregnancy and is usually caused by
a small benign tumor at the base of the brain. This
condition is treated medically with bromocriptine (Parlodel)
or surgically by removing the tumor.
ovulatory cycle is a complex biologic interaction of
numerous hormones and organ systems. Reproductive
endocrinologists undergo advanced training to enable
accurate diagnosis and treatment of the many causes
of infertility. Medications, such as Clomid,
should only be prescribed after a thorough evaluation
of the male and female.
The Good Egg...Everything You Need to Know About Ovulation
Said T. Daneshmand, M.D., FACOG©
- Female Infertility
- Ovarian Reserve Testing
- Overview by Mark Trolice, MD
- Male Factor Infertility
- Cervical Factor Infertility
- Tubal Factor Infertility
- Uterine Factor Infertility
- Unexplained Infertility
- Infertility Overview- Samuel Thatcher, MD
REPRODUCTIVE OPTIONS IN ONCOLOGY PATIENTS ,
by Bradford Kolb, M.D., F.A.C.O.G.,
Board Certified, Reproductive Endocrinology and Infertility
CONTEMPORARY FERTILITY EVALUATION, by Daniel Potter, M.D., F.A.C.O.G.,
Board Certified, Reproductive Endocrinology and Infertility,
Huntington Reproductive Center