Pinpointing Fertile Days

Print out this step-by-step guide to boost your baby-making know-how

By the editors of Parents magazine

What's the most important thing to know about getting pregnant? It's all in the timing. Follow our step-by-step guide to determine when you are most likely to conceive.

(Keep in mind that, on average, it takes six to eight months to conceive, and that, in any given month, you probably have a 15 to 20 percent chance of getting pregnant. So don't be too focused on fast results -- just try to relax and have fun!)

Step 1: Keep track of your periods.

Is your menstrual cycle regular? How many days elapse between your periods? These are the first important pieces of information to know. If you're not sure how long and how regular your cycles are, here's how to find out:

Mark your calendar on the day you get your period. This is Day One. Count each day until your next period arrives (when you'll begin at Day One again).
You may need to do this for three or four months to get an accurate measure of the length and regularity of your cycle. The average menstrual cycle is 28 days long, but normal cycles can range from 23 to 35 days in length. And of course, cycles can vary in length from month to month.

Step 2: Determine when you ovulate.

The key to conception is having sex during a small window of time around ovulation, when a ripened egg is released from one of the ovaries and moves into the fallopian tube. So, the second important thing you need to know to pinpoint your most fertile days is when you ovulate. Here's how to find out:

If your cycles are very regular, you may be able to determine when you ovulate by doing some simple math: in the average menstrual cycle, ovulation occurs 14 days before the menstrual period arrives -- or on day 14 of a 28-day cycle. So if you subtract 14 days from the length of your cycle, you'll get an idea of when you ovulate.

If your cycles aren't very regular, or you'd like a more accurate picture of your ovulation, you can try one of the following techniques for pinpointing ovulation:

Track your temperature. One of the tip-offs that ovulation has occurred is that a woman's regular body temperature (or basal body temperature) increases slightly. You can detect this "thermal shift" by taking your temperature every morning at the same time before you get out of bed. If you chart your temperature each day for a few months, you'll probably begin to see a pattern that will help you predict when you are about to ovulate. Most women's temperature increases about a half a degree 24 to 48 hours after ovulation. (You may want to buy a special basal body temperature thermometer, which is more sensitive than a regular thermometer).
Use an ovulation predictor kit. This method is more expensive than tracking your temperature, but may be more accurate. Available in drugstores, an ovulation predictor kit measures the level of luteinizing hormone (LH) in your urine. By testing your urine using the kit (this usually involves urinating on tester sticks), you can find out when LH levels are rising, a sign that one of your ovaries is about to release an egg.
Watch for changes in your cervical mucus. This low-tech method for monitoring fertility won't pinpoint exactly when you've ovulated, but it will give you some indication of whether you're in a fertile period or not. As your body prepares to ovulate, it produces larger quantities of thin, clear cervical mucus, a substance that smoothes the way for the sperm to meet the egg. On your most fertile days, just before ovulation, the mucus will appear clear, stretchy, and slippery -- a bit like raw egg whites. After ovulation, when your fertile days are past, the mucus usually becomes thicker, then gradually dries up. To collect a sample of your cervical mucus, gently wipe your vaginal opening with toilet paper or a clean finger. (If you try this several times over a single day and don't see any mucus at all, you're probably not in a fertile period of your cycle.)

Step 3: Figure out when to have sex.

Once you have a clear picture of your cycle, there's only one thing left to do -- get down to business! This is probably the most misunderstood part of the conception puzzle. For example, if you have intercourse once you've ovulated, you may be too late! Most healthcare practitioners advise you to have sex every day or every other day beginning about five days before ovulation, and continuing through the day after ovulation. Why? Because, though sperm can live as long as three to five days inside a woman's body, an egg's life span is only about 12 to 24 hours. By having intercourse before you ovulate, as well as on the day of and the day after ovulation, you maximize your chances of getting pregnant.

How much is too much? Some couples are concerned that having frequent sex will deplete the man's sperm supply. But healthy testes constantly generate fresh sperm, so daily sex shouldn't pose a problem.

What position is best? Whichever position feels best! It doesn't matter to the sperm or the egg which sexual position you use -- and it's not necessary to stay in bed, stand on your head, or do anything else special to help things along. Just do what comes naturally, and enjoy!

So what if you don't get pregnant?

If you're under 35 and have had properly timed intercourse for 12 months, or 35 or older and have been trying for six months, then it's time to see the doctor for a fertility evaluation. Talk to your ObGyn about where to begin, and see our guide to basic fertility tests.