|Ovulation? Who? What?
Common Misconceptions About Our Fertile Time of the Month
We’ve all heard of ovulation, a certain time of the month when we are more likely to conceive. But do you really know what ovulation means? Unless you are in a health-related field, most formal education in women’s biology ended in middle school or high school, perhaps at a time when you could not even relate to the information, or might have been too embarrassed to really listen and ask questions. And a 15-minute visit to the gynecologist does not usually allow us to clarify the finer points of our monthly cycle.
A background in science is definitely not necessary for understanding our bodies. This article is intended to give a basic overview of the menstrual cycle in a healthy, non-pregnant woman, with an emphasis on understanding ovulation. It is my hope that this article will empower you to look into birth control methods that are right for you, feel more comfortable asking your doctor questions and clarify some common assumptions.
To begin,the menstrual cycle can be divided into three phases described below. In each phase, changes in both our ovaries and our uterus are preparing for possible pregnancy. These changes are orchestrated by a handful of hormones, including progesterone and estrogen.
Follicular Phase: This phase begins on the first day that we begin our period, lasts until ovulation, and varies in length. In a 28-day cycle, this phase lasts from day 1-13. It is more variable in length than the other phases and accounts for the difference when cycles are shorter or longer than 28 days. During this phase, the lining of our uterus (also called the endometrium) sheds and we have our period, consisting of cervical mucus, vaginal secretions, endometrial tissue and blood. Once bleeding stops, the endometrium begins to thicken. Meanwhile, a few eggs within our ovaries begin to grow and mature in sacs called follicles (hence follicular phase).
Ovulatory Phase: Ovulation is the release of one mature egg from a follicle into one of the fallopian tubes that lead to the uterus. Ovulation usually occurs on day 14 of a 28-day cycle. Sperm travels up from the vagina, through the cervix (the opening of the uterus), through the uterus and into the fallopian tubes where the sperm meet the egg and conception occurs.
Luteal Phase: This phase lasts about 14 days, between ovulation and the first day of our period. It is the most consistent phase in length. Women with a 24-day cycle or a 32-day cycle, for example, will both have a luteal phase of 14 days. During the first part of this phase, the endometrium continues to thicken with nutrients, ready to receive a fertilized egg. In the second half of this phase, hormone levels begin to change and our period begins again, marking the first day of the follicular phase.
It is very common for women to assume that they ovulate on day 14 of their cycle. This is not necessarily true. The first part of the cycle (follicular phase) is the most variable in length and the third phase (luteal phase) is the most constant. This means that in a 28-day cycle ovulation is on day 14. But only a small percentage of us actually have a 28-day cycle. It is normal for cycles to range from 21-35 days. If your cycle is 32 days, for example, then ovulation occurs on day 18. We get this number by subtracting 14 (the length of the luteal phase) from 32. If your cycle is 24 days, then ovulation occurs on day 10. Those of us with very consistent cycles can easily figure out our day of ovulation. But many of us have cycles that vary every month or with stress.
Fortunately, there are signs of ovulation even if we’re irregular. One sign is a slight dip in body temperature the day before ovulation, followed by a rise in temperature during ovulation. Basal body temperature (BBT) thermometers can be purchased at your local drug store to help you chart your temperature throughout your cycle. Another sign that ovulation is approaching is a change in cervical mucus, or vaginal discharge. About 6 days before ovulation this mucus becomes clear and very stretchy, almost like egg whites. This type of mucus helps sperm reach the unfertilized egg. Finally, we can even test our urine for luteinizing hormone (LH) with an ovulation predictor kit found at a drug store. LH is one of the hormones that signals our ovaries to release an egg at ovulation, and testing this hormone can predict ovulation 22-36 hours in advance. For more information on these methods of ovulation prediction, check out WebMD online and type keywords like “basal body temperature” or “natural family planning” into the search field (http://www.webmd.com).
Another common assumption is that we are fertile only on the day of ovulation. Actually, we are fertile before we ovulate. Our “fertile window” is the period of time that conception is likely to occur. It is generally agreed that this window is 6 days—5 days before ovulation and the day of ovulation itself. Sperm can live up to 5 days in fertile cervical mucus. This mucus quickly changes the day after we ovulate, making conception at this point much more unlikely. In a 28-day cycle, the fertile window would be days 9-14, not just day 14! Out of the three signs of ovulation described above, only cervical mucus will indicate the beginning of the fertile window. Monitoring our basal body temperature and LH levels helps us to predict ovulation within a couple days at the most. Even in the most regular cycle we can’t predict with absolute certainty the day of ovulation. No method is completely accurate all the time, and I would advise anyone choosing a birth control method or who may want to conceive to speak with her doctor.
Each one of us is in charge of our own wellness. Sometimes this may seem overwhelming when so many of the terms used to measure and describe our bodies sound foreign, especially for those of us without a background in science. However, it really doesn’t take a rocket scientist to understand this stuff! Even with some basic knowledge, we can ask more informed questions and better understand the answers. Developing this dialogue with our health care providers empowers us to take responsibility for our well-being!
Anne Cabrinha, L.Ac.