Calculating the Fertile Period

My husband and I have been trying to have a child for several months. The books I've read have differing advice on when the woman is the most fertile. Some say 14 days after the first day of your period, some say 14 days before you think you are going to start your next period, and so on. I am just clueless on when my most fertile time would be. Could you shed some light on this?



To maintain a healthy relationship while attempting conception, it is important to remember that lovemaking and babymaking are different and to take steps to ensure that you have enough time for both. That is why I believe your question is so important. If you can accurately predict your most fertile period, you can limit your babymaking time and increase the lovemaking time. Hopefully that will reduce your stress and strengthen the bonds between you and your spouse. So here goes:

One method to detect your most fertile period is to use a basal body temperature (BBT) chart. In brief, you take your temperature when you awake each morning, before you get out of bed; this is when your temperature is at its lowest for the day. When you ovulate, your ovary starts producing progesterone to get the uterus ready for implantation; this hormone also increases your basal body temperature about half a degree Fahrenheit.

Of course, once your temperature rises, you have already ovulated. That means it is likely too late to conceive. The old axiom is that the guy is supposed to arrive early for a date and wait for the girl to be ready. While we have become more egalitarian socially, the sperm and egg have not dropped such sexual stereotypes -- sperm need to be in place before the egg is released. That means you need to have intercourse one to three days before the temperature rise to ensure that sperm are present at your most fertile time. So, don't look at the temperature chart and ask your husband to jump into bed. And don't look for dips, swirls or other phenomena in the chart to predict anything. The chart is just not that accurate. In fact, studies have shown that you can ovulate up to three days before or after the temperature rise.

Since a chart cannot tell you in advance when you will ovulate for any single month, its value is in helping you identify your patterns. For you to use the charts effectively, your menstrual cycles must be regular within a few days -- say, they might occur every 28-30 days or every 33-35 days. Then you can look at a few months of charts and see where the temperature rise occurs. It would normally occur sometime between days 12- 19; for example, you might routinely detect yours on day 14. Once you can predict the day on which the rise is likely to occur, start with babymaking intercourse about four days before the expected rise and repeat every other day for about a week.

If your cycles are regular, you can also predict the day of expected fertile interval without the BBT charts. First, calculate the average length of your cycle, from the beginning of one period to the beginning of the next. (You can count your first day of heavy flow as day 1; if your heavy flow begins in the evening, count the following day as day 1. What's important is to be consistent in how you define the start of your period.) Subtract 18 days from the total number in your cycle, and begin babymaking intercourse every other day for one week. So if your cycles are 30 days, subtract 18 to get 12. That means you have intercourse on days 12, 14, 16, and 18.

Many couples prefer to further limit the stress of babymaking intercourse by using a ovulation predictor kit from the drugstore. Start testing your urine each morning according the above schedule. So, for a 30-day cycle, begin testing on day 12. When the test stick changes color, that means ovulation should occur the next day. Unfortunately, accuracy is about 85 percent, and confusion can occur for those on clomiphene (fertility pills). I advise couples to consider babymaking on each day there is a color change and the day after the darkest indication.