Getting pregnant is a lot like starting a fire. When you want to get a pile of tinder burning, it takes considerable effort. Drop a match by accident and a forest ignites. It can often seem like, for every teenager with an unwanted pregnancy, there are two adults struggling to make a baby. And while fertility problems occasionally need advanced medical interventions to resolve, a lot of winning the conception lottery comes down to plain old good timing. Fortunately, a bit of planning can make hitting the necessary marks considerably easier.
Nearly one fifth of young women suspect that they are infertile solely because they had unprotected sex and did not get pregnant, according to a recent study. This sheds light on just how little the average would-be parent knows about the likelihood of conceiving. Studies suggest even partners who have frequent, unprotected sex only have an 85 percent chance of becoming pregnant within one year. And, it may not be the sort of thing you want to tell sexually active teens, but our odds of becoming pregnant from unprotected sex on any given day are about 3 percent. Even that number varies widely, based on timing. During her period, a woman has almost no chance of getting pregnant. Just before she ovulates, it’s closer to 10 percent.
Although you probably have a basic idea of the contours of the menstrual cycle, a review is always helpful. When a woman gets her period, that is considered Day 1 of her cycle. It’s hard to miss. At that point, the ovaries are in the follicular phase—an egg is maturing within a follicle. About two weeks after the onset of a period, the follicle normally releases its egg and the egg travels down the fallopian tubes into the uterus. This is ovulation and it’s far easier to miss. Some women experience cramping or spotting. Most have no symptoms.
Ovulation kicks off the luteal phase, during which the follicle (now the corpus luteum) leaks hormones that prepare the uterus for pregnancy. If the egg was fertilized at some point prior to this phase, the pregnancy happens. If not, the woman enters another menstrual cycle.
A common misconception is that the day of ovulation is a good day to try to conceive. In fact, studies have shown that the best time to conceive is a few days before ovulation. A 2013 study in Human Reproduction calculated the probabilities of getting pregnant on any given day of the menstrual cycle. The odds start at near zero on Day 1, and climb steadily until Day 14, just before ovulation. At that point, the odds of becoming pregnant drop off again.
The goal, then, is to spend some alone time together right before ovulation. Counting days can help (aim for days 12-14 of your cycle) but, since the length of any given cycle can vary, it helps to keep a lookout for other telltale signs of impending ovulation. Women tend to have higher body temperatures on the day of ovulation and, for diehard conception enthusiasts, commercial ovulation test kits are available to inform women a day or two before ovulation.
Even if you nail the window, there is no guarantee that you will conceive. But it sure stacks the deck in your favor. If you continue to have trouble conceiving after about a year of trying during the proper times, it is a good idea to ask your doctor about potential fertility treatments.