The first day of your menstrual period – of regular flow, not just spotting – is considered cycle day 1. Ovulation occurs somewhere close to the middle of your cycle, so if you have a “normal” 28-day cycle, you should ovulate on approximately cycle day 14. However, the term “normal” is used loosely when it comes to cycle lengths. There are many women who do NOT have 28-day cycles, and for those women, ovulation can occur either earlier or later than cycle day 14. If your cycle is generally about 34 days long, for example, you probably ovulate on cycle day 20 or so, not on day 14. So if you’ve been timing your intercourse around cycle day 14, and you have a cycle that is longer than 28 days, you’re missing your fertile window. Your period comes two weeks after ovulation has occurred, whatever your cycle length.
There are several ways to determine when you’re most fertile. One of the easiest methods is to use an ovulation predictor kit (also called OPK). These are tests that look and act very similar to pregnancy tests and are usually found in the same aisle at the store. Like pregnancy tests, you urinate on a stick to determine the results. Right before ovulation occurs, your body sends out a surge of luteinizing hormone, or LH. If the OPK detects an LH surge in your urine, it will be positive – you’re about to ovulate, so let the baby-making begin! If the test is negative, just wait a few days and try again.
Charting your basal body temperature is another way of tracking your ovulation patterns. Every morning at the same time, before getting out of bed, take your temperature using a basal body temperature – or BBT – thermometer (which are readily available at drugstores). After ovulation has occurred, extra progesterone in your system causes your temperature to increase, where it holds steady at the higher temperature until your period starts, then drops again. You can plot each morning’s temperature on a graph, or a BBT chart, and be able to see on which day you ovulated by looking for the temperature “spike.” This doesn’t predict ovulation in advance, but after charting for a few months, it can be a very useful tool in determining your own personal patterns and planning accordingly.
Checking the cervix and/or cervical mucus is another way of determining when ovulation is approaching, although it is a method that doesn’t appeal to everyone. The cervix is the “mouth” of the uterus and can be felt by inserting a (clean!) finger into the vagina. That mass of tissue you feel at your fingertip is the cervix. When you’re not close to your fertile time, it will be low and easy to reach, and feel firm, like the tip of your nose. Its opening, called the os, will be closed tightly. However, as ovulation approaches, the cervix rises higher which may make it more difficult to reach. It also softens, and will feel more like your lip than your nose. The os will be open, and you’ll be able to feel it as a slight indentation. Another clue is your cervical mucus: if it is clear and slippery and looks very much like egg white, it is fertile mucus and signals impending ovulation.