If you’ve seen Woody Allen’s Everything You Always Wanted to Know About Sex (But Were Afraid to Ask), it’s easy to imagine baby-making on the cellular level. The final scene of the movie depicts a squadron of long-tailed sperm waiting for their big moment dressed in white suits, hoods and gloves. While most of the guys wait patiently for things between their host and his lady friend to heat up, Allen works himself into a characteristic stupor, sperm-style: he’s scared, he’s worried, he’s due at his mother’s for dinner. Meanwhile, his comrades are full of the machismo you’d expect from a bunch of sperm. Their mission? “To fertilize an egg or die trying.” At last, the door of their futuristic pod slides open and the guys begin to eject in single file. Capturing the excitement of the moment, one white-hooded spermatozoa jumps off the brink and shouts, “We’re going to make a baby!”
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Well, maybe. The truth is that no matter how ardently these fellas (or their real-life counterparts) want to make a baby, a successful pregnancy depends on many factors. Enthusiastic sperm and a viable egg, yes, but also a complex variety of hormones, a series of chain reactions, good timing and a little bit of luck. And no matter what you were told in high school, in reality, you don’t always get pregnant the moment you throw caution to the wind and hop into bed. According to Elaine Herer, an obstetrician/gynaecologist at Sunnybrook and Women’s College Health Sciences Centre in Toronto, “It depends on the woman’s age. The younger you are, the easier it may be to conceive. However, even with the perfect situation — the right timing, great sperm, open tubes, etc.—we are talking about a 20 percent chance, per month.” Still, our bodies are designed for procreation, and the stats bear this out. “At the end of six months of unprotected sex,” says Herer, “80 percent of women are pregnant. At the end of one year, 90 percent.”
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And what if you’re not a tender 25 years old when you start trying? Roger Pierson, a professor of obstetrics and gynaecology at the University of Saskatchewan, says that the probability of conceiving starts to decrease before age 30. “If you’re 30 to 34, you have a 12 to 14 percent chance per cycle,” he says. “If you’re between 35 and 39, you have a 7 to 9 percent chance per cycle.”
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How It Happens
Clearly, there’s more to making a baby than making love, even if our bodies do most of the work without us knowing it. For starters, consider the hardworking sperm. All they need is a lift into the vagina before they take off on their own and swim up to the cervix (the opening to the uterus). But according to Sherman Silber, MD, author of How to Get Pregnant With the New Technology, the journey toward the egg soon becomes tough slogging, because the sperm have to get through a thick liquid called cervical mucus (more on this important fluid later). The first strong swimmers to reach the mucus blaze a trail for the others, who follow in single file.
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Although this slow march toward the fallopian tubes (at the top of the uterus, either side) seems like it might diminish the chances of fertilization, it actually does the opposite. If all of the sperm were to arrive at the site of fertilization at once, the egg would need to be right there, right then. The window for fertilization would last only as long as the egg—12 hours. But sperm can live much longer—usually 36 to 48 hours (although Pierson says there is some evidence of sperm living in the female reproductive system for 9 to 10 days!). This staggered arrival in the fallopian tubes means that sperm are more likely to be around to fertilize the egg, even if the egg has not yet arrived at the time of intercourse.
Meanwhile, the egg has its own path to follow. Baby girls are born with all of the eggs they will have throughout their lifetime stored in their ovaries. Once a young woman starts to menstruate, hormones stimulate a bunch of her eggs to mature each month, and each month, one of those eggs gets a jump on all the others. Since it is the first to mature, this is the egg that is released from the ovary and sent down the tubes for potential fertilization. Ovulation is the term used to describe the process of the mature egg leaving the ovary.
Once released, the egg does not have far to travel before it reaches one of the fallopian tubes. If the timing is right and the stars are aligned, one of the thousands of sperm it meets up with will be strong enough and persistent enough to penetrate the egg’s tough outer membrane. Getting into the egg is not easy—it can take up to an hour of digging and wriggling for a sperm to break through. But once one lucky guy gets in, that’s it. The egg makes its outer walls impenetrable to all others.
For three days, the fertilized egg stays in the fallopian tube, where its cells divide at a rapid clip. Finally, around day four, the egg—now an embryo—is ready to move from the fallopian tube into the uterus. If all goes well, implantation in the uterus will occur by the seventh day. Then and only then is the process of conception complete and the pregnancy established.
Sperm longevity expands a woman’s fertile window from 12 hours to a couple of days, but good timing is still key to a successful pregnancy. In fact, deciding when to “do it” is probably the most heavily discussed aspect of baby making. And yet, for 31-year-old Susie Kahan, a native Edmontonian who now lives in the US with her husband and two young daughters, simply looking at the calendar was enough. “When I got pregnant with [elder daughter] Ana, I was 28. At that point, I didn’t realize that people could have so much trouble. I just knew that you ovulated in the middle of your cycle. So if I got my period on a Tuesday, then two weeks later on the Tuesday, I said, ‘OK, let’s go. I think I’m ovulating!’ I had sex the day before, the day of and the day after. The first or the second month, I got pregnant.”
Pierson confirms that the typical woman with a typical 28-day cycle will ovulate on or around day 14, so Kahan’s approach makes good biological sense. Still, he hastens to point out that not everybody is typical. A cycle can be 25 days long; it can be 30 or 32 days. In these cases, ovluation will occur 14 days before the first day of the next period — which may be before or after the midway point of a cycle that is shorter or longer than average. “That ‘normal’ 28-day cycle doesn’t really exist,” he says.
Just ask Christine Smith*. The 38-year-old mother of Kirsten*, nine, and Nicholas*, five, was around the same age as Kahan when she first tried to get pregnant. Nevertheless, her experience was less straightforward. “I think it took me five or six months to get pregnant. It doesn’t sound like that long, but it felt like an eternity,” says Smith, who knows that according to experts, you are not having fertility problems until you have been having well-timed but fruitless intercourse for a full year.
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As it turns out, Smith is one of those women who had a normal but not necessarily typical cycle. “At that time my cycle was 35 days long,” she says. The trouble was that Smith didn’t realize her long cycle meant she was ovulating after the 14th day.
So what’s a woman with slightly irregular periods to do? Read her body’s cues, say the experts. Both Pierson and Herer agree that the arrival of clear, stretchy cervical mucus is a reliable sign that ovulation is imminent. What’s more, you don’t have to look very hard to find the evidence: Cervical mucus simply shows up as vaginal discharge that is a little more copious and a lot more slippery than the stuff you find at other times of the month. (If you’re unsure, try dabbing a bit between your finger and thumb and then slowly move your finger apart. When you’re about to ovulate, the mucus will stretch in between.)
Some women even experience “mittleshmertz”—a twinge or ache low in the abdomen and to one side, when they ovulate. But don’t wait to feel ovulation before becoming amorous, cautions Herer: “In terms of timing intercourse for reproduction, you want to have sex prior to ovulation,” she stresses. “After ovulation does happen, the mucus at the entrance of the cervix becomes thick and tenacious and is difficult if not impossible for the sperm to penetrate.”
“If you have intercourse every other day from day 12 to day 16 and the mucus is stringy and stretchy, you’ve probably covered the fertile period effectively,” adds Pierson, using a 28-day cycle as an index. But why every other day? “Males produce optimum sperm quality when they ejaculate every 36 to 48 hours,” he says. However, just because every other day is good doesn’t mean every other week will be better. “Some people think that if they don’t ejaculate for a week or two before they try, they’ll increase their chances, but they’re wrong. What you get is a bunch of dead sperm in the system. Remember: Fresh sperm are happy sperm,” he says with a chuckle.
Although most of baby making can be explained by physiology and timing, many people believe that the mind also plays an important, though sometimes mysterious, role in creating a new little person. For example, there is not much scientific documentation showing that feelings and emotions affect conception. Nevertheless, Herer says that the anecdotal evidence is hard to ignore. “Women have years of infertility treatment, adopt a child and then go on to conceive spontaneously. Why? Stress affects all of us.”
Christine Smith would agree. She says that the five months she spent trying to conceive happened to be a very busy, stressful time in her life. “I was working day and night and I was very stressed. Then I quit and I got pregnant right after that. I still don’t know if it was a coincidence or not, but the next time I wanted to get pregnant, it happened in the early months.”
The lesson here is not that everyone who doesn’t get pregnant immediately needs to quit work and devote whole days to thinking positive baby thoughts. But as Herer says, stress—whether from work or from the baby making project itself—doesn’t help. “And remember that your ancestors had kids—that’s why you’re here!” she says playfully.
Playful might be a good word to keep in mind as you approach this whole project. After all, baby-making ought to be fun. It can even be funny. If you don’t believe me, just ask Woody Allen.
Ovulation Prediction Kits
Once you decide you want to get pregnant, you tend to want it to happen, like, yesterday. A number of companies have capitalized on this quirk of human nature, coming out with products that take the guesswork out of conception. Ovulation prediction kits are designed to tell a woman when she is about to ovulate, either by testing her saliva or her urine. But according to a helpful Shoppers Drug Mart pharmacist named Christopher, the saliva tests don’t work very well. “They are almost impossible to read and with some, men will get crystallization, too!” More dependable and accurate are the kits that test a woman’s urine. Roger Pierson, a professor of obstetrics and gynaecology at the University of Saskatchewan, says, “Ovulation kits are reasonable if they’re based on detection of luteinizing hormone [LH], which triggers ovulation. Keep in mind, though, that once LH is detected in the urine, it’s already done its job and is being excreted, so the interval from detection in urine to ovulation is only 12 to 18 hours.”
Nevertheless, Elaine Herer, a staff obstetrician/gynaecologist at Sunnybrook and Women’s College Health Sciences Centre in Toronto, says that the kits are expensive and shouldn’t be used as a first approach. “Consider using one if timing is an issue or with artificial insemination methods.” Wondering just how expensive “expensive” is? Well, the reusable Clearplan Fertility Monitor—obviously the Rolls-Royce of ovulation predictors—sells for about $300, plus $60 for a box of 20 test strips. A decent but more middle-of the-road approach, such as the First Response kit, will set you back $52 (includes five test strips).
Conception: What helps and what doesn’t
Susie Kahan laughs when she admits that she laid on her back with her legs up in the air after sex, attempting to increase her chances of conceiving. In truth there is no evidence to show that post-coital contortions and special sexual positions increase the chances of conceiving. (In How to Get Pregnant With the New Technology, Silber does say that lying down for about a half-hour after sex can help a woman conceive if her mate has a low sperm count, but most men don’t.)
On the other hand, Herer says that there are certain factors that can decrease your chances of becoming pregnant: for example, lifestyle habits such as smoking, drug use and excessive alcohol use. Since you’ll want to quit these harmful habits once you are pregnant, it makes a lot of sense to give them up now. Using lubricants during intercourse can lower your success rate, too, so you might want to give them a pass.
Some medical conditions can make pregnancy more difficult to achieve. If you’re having trouble conceiving, consult with your doctor.
Herer adds that any woman considering pregnancy should take folic acid, ideally from three months before conception. It won’t increase your chances of conceiving, she says, but it will help protect the future fetus against neural tube defects like spina bifida.
* Names changed for privacy.