New research reveals that every woman should take steps today to protect her fertility, regardless of whether she has babies on the brain or can't imagine being a mom for a while (or ever). This step-by-step plan will not only help you have a healthy family, it'll keep you strong and fit for years to come.

What every woman should do now
Yes, fertility does decline with age, but your lifestyle and your environment have a huge impact on your pregnancy potential. "If you're proactive about protecting your heart and your brain, you're also safeguarding your reproductive health. It's a nice bonus," says Pamela Madsen, founder and executive director of the American Fertility Association in New York. "We call it 'Lifestyles of the Fit and Fertile.' " You may be surprised by how many of the steps on this list you're already taking to stay healthy.

Reach a healthy weight
If you carry extra pounds, you have an increased risk of diabetes, hypertension, and cardiovascular disease; losing weight will improve your health and your ability to conceive. A body mass index (BMI) of 18.5 to 24.9, the best indicator of a healthy weight, is most favorable for fertility. (Calculate yours at shape.com/tools.) A study published in the journal Human Reproduction found that the more weight a woman gained between pregnancies, the longer it took for her to conceive. Being over- or underweight can throw your hormone levels out of whack--and an imbalance of estrogen, the key hormone for ovulation, will reduce your odds of getting pregnant. Once you conceive, an unhealthy weight also makes carrying a baby more difficult-and more dangerous. There's a clear link between obesity and the rise in pregnancy complications, like gestational diabetes, high blood pressure, and prolonged labor. On the other hand, an underweight woman's body may not be prepared to deal with the extra nutritional demands of pregnancy.

Make exercise a priority
Today, fewer than 14 percent of American women get 30 minutes of activity most days of the week, according to a recent study in the journal Medicine & Science in Sports & Exercise; after conception, that number plummets to about 6 percent. The ideal time to start an exercise plan is before you get pregnant. That way, once you conceive, you'll already be in the habit. Regular cardio during pregnancy may help relieve morning-sickness symptoms and reduce water retention, leg cramps, and excess weight gain--as well as boost your energy and endurance. Start with a realistic goal, like walking a few days during lunchtime.

Clear the air
Smoking just six to 10 cigarettes a day reduces your chances of getting pregnant during any given month by 15 percent, according to a study in the American Journal of Epidemiology. The 4,000-plus chemicals in cigarette smoke have been proven to lower estrogen. "Smoking also seems to reduce the quality and quantity of a woman's egg supply, meaning that it speeds up the natural process of egg loss that occurs as women age," says Daniel Potter, M.D., author of What to Do When You Can't Get Pregnant. Smoking during pregnancy accounts for 20 to 30 percent of low-birth-weight babies and for about 10 percent of infant deaths, according to the U.S. Surgeon General.

Nonsmokers should also take steps to minimize their secondhand exposure--it can lead to abnormal lung function in a developing fetus and low birth weight. And after you deliver, a child exposed to cigarette smoke is especially vulnerable to ear infections, allergies, and upper-respiratory infections.

Take a multivitamin every day
Even women who eat a healthy diet don't always get enough nutrients to ensure a healthy pregnancy. A vitamin-mineral supplement helps you cover all your bases. Iron, in particular, seems to bolster fertility: A recent study of more than 18,000 women published in the journal Obstetrics & Gynecology found that women who took iron supplements cut their odds of infertility by 40 percent. So opt for a multi with iron--especially if you're a vegetarian or you don't eat much red meat.

Another key nutrient, folic acid, won't improve your chances of conceiving, but the B vitamin will drastically reduce a developing baby's risk of neural tube defects--often fatal birth defects of the brain and spinal cord like anencephaly or spina bifida. Taking folic acid now is key because these systems develop during the first few weeks after conception--before many women realize they're pregnant--and if you have a deficiency it can cause irreversible damage. Experts recommend you begin taking 400 micrograms of folic acid a day for at least four months before you get pregnant.

Practice safe sex
Using condoms every time you have intercourse will help you avoid unwanted pregnancy and drastically reduce your risk of contracting sexually transmitted infections that can wreck your reproductive health. Diseases like chlamydia and gonorrhea can damage your fallopian tubes and make conception difficult. They have few symptoms and often go undetected for years. The pill, the patch, and other types of hormonal contraceptives don't shield you from STDs, but they can protect you from pelvic inflammatory disease (PID), ovarian cysts, and uterine and ovarian cancer, which can interfere with conception.