Ovaries and Ovulation
Female Reproductive System
What causes ovulation?
Ovulation occurs in the ovaries. The ovaries are located next to the uterus and just within the grasp of the fallopian tube.
During the first two weeks of a 28 day menstrual cycle, the hormone FSH (follicle stimulating hormone) stimulates egg maturation within ovarian follicles. One of the ovarian follicles will become dominant and the egg inside this follicle will mature fully and be released at ovulation time. The other ovarian follicles and their eggs will wither away. When the egg bursts forth from the ovarian follicle, a hole appears in the surface of the ovary. Repeated ovulations month after month make the surface of the ovary become wrinkled and pitted. Dr. Berger looks at the appearance of the ovaries for these signs of repeated ovulation when he performs tubal reversal surgery. Follicle rupture may be felt as ovulation pain in one side of the lower abdomen.
When does ovulation occur?
The timing of ovulation varies with the length of a woman's menstrual cycle. In the average 28 day menstrual cycle, the LH surge usually occurs between cycle days 11-13 and ovulation follows about 36-48 hours later, on or close to cycle day 14. (It is the mid-cycle surge of the hormone LH that causes the dominant follicle to rupture and release the mature egg.) Women with shorter menstrual cycle lengths tend to ovulate earlier and women with longer cycle lengths tend to ovulate later than cycle day 14. Despite the variations in menstrual cycle length, the time from ovulation to the onset of the next menstrual period is usually constant (2 weeks). This principle is the basis for the use of ovulation calendars that take into account an individual's shortest and longest cycle lengths.
When is the most fertile time in the menstrual cycle?
The days from the LH surge to the day after ovulation are the most fertile days in a woman's menstrual cycle. When trying to conceive a pregnancy after tubal reversal surgery, it is helpful to know when pregnancy is most likely to occur. Ovulation calendars, temperature charts, and ovulation predictor kits are helpful in this regard. Of these 3 techniques, the ovulation predictor kit (OPK) is the most accurate. These at-home urine tests identify impending ovulation by detecting the LH surge. Ovulation calendars and temperature charts provide only approximations of the fertile time of the cycle.
More information is available about ovulation on the Tubal Reversal web site.
Female Reproductive System
- Uterus - uterine anatomy and menstrual cycle
- Fallopian Tubes - tubal anatomy and functions
- Fallopian Tube Length - Fallopian tube length from the Tubal Reversal Message Board
- Ovaries and Ovulation - ovulation requires egg maturation and release from the ovary
- Ovulation monitoring - ovulation predictor kits and basal body temperature charts
- Cycle Day 3 FSH - Follicle Stimulating Hormone and when should it be tested
- Early Pregnancy Signs - and When They Occur