Your TTC Strategy 5: Predict OvulationDeborah Metzger, MD
Family Planning Boards
Getting pregnant can be the easiest or most frustrating event in your life. When you’re trying to conceive, timing is everything. Perfect eggs and flawless sperm are useless if they don’t hook up at the opportune moment. To make that happen, you need to have intercourse within 24 hours of ovulation (when the ripened egg is released from the ovary).
There are several ways to determine if you are ovulating: Regular, predictable menstrual cycles (especially if preceded by symptoms such as bloating, breast tenderness, or moodiness) are a great indication that ovulation has occurred. If you do not have periods or you have irregular cycles, this means you are either not ovulating or you’re ovulating unpredictably. It is important that women who have irregular cycles consult their healthcare provider before they try to get pregnant so that the obstacles to ovulation can be identified and treated.
Studies have shown that conception occurs more quickly when some method of ovulation prediction is used to time intercourse. There are a variety of low-tech and high-tech approaches that can help determine when ovulation is taking place.
Keeping track of when your periods start will clue you in to the “window of opportunity”—when ovulation is likely to occur. Ovulation usually occurs 14 days before the onset of menses. For women with a 28 day cycle, this means cycle day 14, but for women with normal but varying cycle lengths (26 to 35 days), it could be anywhere from day 12 to day 21! In order to cover the possible time of ovulation, these women are advised to have intercourse every 36 to 48 hours from day 10 until day 23. For women with less variable menstrual cycles, the fertility window may cover fewer days.
Mittelschmerz, from the German for “middle pain,” is a sharp or aching pain in the lower left or right of a woman’s abdomen that last 12 to 36 hours. It occurs when an egg is being released from the ovary. It signals the “perfect” time to have intercourse. Keep in mind that only 20 percent of women feel or notice this pain, so you may want to employ a more reliable method to detect ovulation.
A woman’s cervical mucus changes consistency in concert with the hormonal changes during the menstrual cycle. Changes in your cervical mucus can help identify your fertile phase without the need for any special devices. For a few days after your period, your cervical fluid may be dry or sticky; then it starts to get wetter. When it becomes slippery and stretchy—almost like a raw egg white—that’s when you’re most fertile.
Ovulation Predictor Kits
One detectable sign of oncoming ovulation is the position of the cervix itself. During the beginning of a cycle, your cervix is low in the vagina, hard, and closed. But as ovulation approaches, it pulls back up, softens a bit, and opens just a little, to let the sperm through on their way to their target. Some women can easily feel these changes, while others have a tougher time. Check your cervix daily, using one or two fingers, and keep a chart of your observations.
The basal body temperature (BBT) chart helps to determine if and when ovulation has occurred. During the follicular phase, a woman’s body temperature is relatively low. When progesterone production begins at ovulation, it produces a temperature rise that can be detected on a special BBT thermometer, available at most drug stores for $10 to $15. An increased body temperature for several days indicates ovulation has occurred. BBT charts cannot predict when ovulation is going to occur; they only confirm that ovulation has occurred after the fact. Some women will monitor changes in their cervical mucus along with their BBT. Used over time, however, BBT charts can indicate by patterns your likely fertile days, or provide you accurate details about irregular cycles.
If having sex every 36 to 48 hours during your fertility period isn’t convenient for you and your partner, then the ability to clearly identify when ovulation will occur is the best method for you. The most popular type of ovulation predictor tests morning urine for LH, which is released about 24 hours prior to ovulation. Another type of ovulation kit measures estrogen levels in saliva. You apply a bit of saliva to a lens, then examine it under a microscope. Another device measures the amount of chloride in your sweat.
As the follicle undergoes development, blood estradiol levels increase and peak just before ovulation—these can be measured with simple blood tests. Elevated progesterone levels in the blood usually are associated with ovulation. A blood test to measure progesterone can be performed about one week before the anticipated onset of the next menstrual period or one week after ovulation.
Follicular growth can be measured with ultrasound, a technique which uses sound waves to produce an image on a monitor screen. This is a painless procedure usually done with a probe inserted into the vagina. Prior to ovulation, the follicle is thin-walled and filled with fluid. As the egg inside the follicle develops, the follicle increases in size. Ovulation generally occurs when the follicle measures about 1.8 to 2.5 centimeters. A medication that causes ovulation (hCG) can be administered to allow timing of intercourse.
Progesterone, a hormone released by the ovaries, helps prepare the endometrium, the lining of the uterus, to receive an embryo. An endometrial biopsy is occasionally used to determine if a woman has ovulated, and if the endometrium has been adequately stimulated with progesterone. During this office procedure, a small amount of endometrial tissue from inside the uterine cavity is removed and examined under a microscope. This test is performed just before menstruation is expected to begin.
For couples who are trying to conceive a baby, the key to success is knowing when a woman is most fertile during her monthly menstrual cycle. Most of the methods do not require any special equipment and can be done at home by the couple. Others require simple, low-cost equipment. Blood testing, ultrasound, and endometrial biopsy require medical intervention and are usually used for infertility evaluation or treatment.