It’s being said that if you want a baby born on 11-11-11, you should “get ready to get on it this weekend.” So…
By Allen J. Wilcox
You already know where babies come from – the business about sperm and eggs, and getting them together. You also know something about birth control – after all, people spend most of their reproductive years trying NOT to get pregnant.
But there comes a time for many women when they ready to have a baby. That’s when some interesting questions arise.
- Once you stop using birth control, how long does it take to get pregnant?
- Is there something women should do to increase their chances of getting pregnant?
- What can a woman do to help make sure her baby will be healthy?
Let’s start with the last question first. The most important thing a woman can do before getting pregnant is to start taking daily multivitamins with folic acid. Folic acid helps prevent serious birth defects of the brain and spine (neural tube defects) and probably other defects as well. These defects happen very early in the baby’s development – waiting until you think you are pregnant can be too late.
Another thing you can do, if you are a smoker, is to quit smoking. Smoking puts a damper on women’s fertility (although apparently not on the fertility of men – life is not fair). Smoking also increases the small chance of fetal death later in pregnancy. Do yourself (and your baby) a favor, and give up the cigarettes.
Besides that, what should you do (besides the obvious)?
Really, nothing. You already have a lot going for you. Consider the benefits of your family history – not a single one of your ancestors was infertile. If you are a reasonably healthy person with no history of reproductive problems, and if you are having unprotected sex at least weekly, biology is on your side.
Some useful facts
There is a spectrum of fertility, ranging from very low to very high. You won’t know where you are on that spectrum until you actually try to conceive. On average, your chance of getting pregnant in the first month is 25%. For a few unlucky couples, the chances are zero – they are sterile. Other couples may have a 50% or 75% chance of getting pregnant in their very first month of trying. For couples as a whole, about half will be pregnant after three months. That goes up to two-thirds of couples after six months, and more than 90% after a year. Even if you don’t conceive in the first year, you still have a 50% chance in the next year or so. Only about 5% or so of couples are unable to conceive at all by natural means.
Probably the biggest predictor of fertility is woman’s age. Women are at their reproductive peak during their twenties. As they move through their thirties, their fertility begins to decline. This is relevant because many women (for lots of good reasons) delay their childbearing until they are in their 30s or even older. If a woman is not so fertile to start with, this delay can cause problems. Unfortunately, there is no medical test to tell women in advance how fertile they are.
The fertility window
Let’s get down to the biology. Pregnancy happens when couples have sex during the five days before ovulation and the day of ovulation itself. (In other words, sperm can survive up to five days in the woman’s reproductive tract.) This six-day fertility window gives you a fairly wide span of days in each cycle for intercourse that can produce pregnancy.
But there is a catch. Most women don’t know when they ovulate, which means they don’t know their fertile days. You might worry that you won’t have sex on the right days, but your body helps take care of that. We don’t understand how this happens, but couples naturally have more sex on the fertile days than on other days. Maybe it is because women get more interested in sex around this time, or because men find women more sexually attractive. Regardless, the good news is that you are having more sex on your fertile days even when you aren’t trying. Once again, Mother Nature is on your side.
You may have heard about over-the-counter “fertility kits.” Their purpose is to help you know your fertile days. Are these worth the bother? Not usually. For one thing, these kits tell you only when you are near the end of your six fertile days, not the beginning. For another, having sex on your most fertile days doesn’t guarantee you will get pregnant. And the kits are not cheap. Given that half of couples conceive in three months with no help at all, you might as well wait a bit to see how things go.
For the vast majority of couples, pregnancy will happen with no problem at all.
Allen J. Wilcox, MD, PhD is Senior Investigator at the National Institute of Environmental Health Sciences (NIH) in Durham, NC, and Editor-in-Chief of Epidemiology. He is a pioneer in reproductive epidemiology, with research projects on topics ranging from fertility and early pregnancy loss to fetal growth and birth defects. Dr. Wilcox is author of Fertility and Pregnancy: An Epidemiologic Perspective.