VII Misconception: "I'm generally healthy, so I'm sure I'm fertile."

Reality: General health does not correlate strongly to fertility, but a healthy lifestyle is important. Women who smoke throw off their estrogen levels, risk tubal pregnancy, and increase the chance of miscarriage, low birth weight, and birth defects.

Male smokers significantly lower their sperm counts and increase the percentage of abnormally shaped sperm. Moderate alcohol consumption—a glass of wine with dinner—probably won't diminish fertility, but much more than that may cause menstrual disorders and abnormal sperm production.

Doctors also warn against excessive caffeine consumption while trying to conceive: Stick to one or two caffeine drinks a day. "Just say no" to any recreational drugs, as even limited use can affect male sexual function and disrupt ovulation. Being overweight or underweight—20 percent off your ideal weight in either direction—may hinder fertility in women. Moderate exercise is good, but women should avoid exercising to the point where their cycles are disrupted.

VIII Misconception: "I'll get pregnant a month or two after I start trying."

Reality: The average couple of 30-year-olds takes six months to conceive naturally. "People think as soon as they try they"re going to get pregnant," says Dr. Friedman. "They hear about all their friends who got pregnant in one month, but the couple who've been trying for a year or more probably isn't announcing that."

About 75 percent of women will get pregnant within six months. Around 15 percent may pass the 12-month mark, which is when a couple is considered "infertile." Before starting to try, a woman should see an ob-gyn for a check-up and make sure that all of her immunizations are up to date.

IX Misconception: "I've had a baby already, so I won't have a problem having more."

Reality: Secondary infertility—having difficulty conceiving after having conceived in the past—is almost as common as primary infertility. Dr. Copperman explains that the causes of secondary infertility are the same problems many couples experience the first time around: "It could be egg quality, tubal disease, uterine problems, or even a newly acquired male factor. So even if a couple has gotten pregnant in the past, if they're having difficulty it's important to go through the basics—check the eggs, sperm, fallopian tubes, and uterus—because we often find that things change over time."

X Misconception: "Infertility is uncommon."