Ovulation is the release of a mature egg(s) from the ovarian follicle(s) and must be regular for conception to occur. Ovulation is preceded by the selection and growth of follicles under the influence of follicle stimulating hormone.
As these follicles mature, they produce estrogen, which helps prepare the endometrium to accept an embryo. If pregnancy occurs, the ovaries and placenta produce progesterone to help support endometrial growth. If pregnancy does not occur, the endometrial tissue breaks down and is excreted as the “monthly menstrual flow”.
There are many ways to predict and document ovulation including basal body temperature (BBT) measurements, direct observation by
ultrasound, progesterone hormone levels, and urinary LH kits.
BBT charting was once the most common means to predict ovulation. If you are using BBT charting, take your temperature every morning before any physical activity. The daily temperature measurements are entered on the chart for several months. A slight rise in temperature is seen each month immediately prior to ovulation. After several months of charting, it is possible to predict which day of your cycle the temperature rise (ovulation) will occur. Intercourse is planned around this time. Obviously, BBT charting is time consuming, inconvenient, and less accurate than other methods.
Most physicians today recommend ovulation predictor kits, which measure the amount of LH in the urine. LH spikes approximately 36 hours prior to ovulation. These kits are very accurate and help the couple insure intercourse occurs near ovulation.
Transvaginal guided ultrasound can be used to monitor follicular development. It can also be used to document that ovulation occurred, however, it cannot predict ovulation. Evidence of ovulation is seen as ruptured follicles on the ovaries.
Increased progesterone levels are an indication that ovulation occurred. The follicular structure remaining on the ovary after ovulation is known as the corpus luteum. The corpus luteum begins to produce progesterone after ovulation.
Sometimes an endometrial biopsy is done to confirm that the endometrium has developed properly to receive the embryo. Improper development may be caused by a luteal phase defect, which can often be treated medically.