http://www.cosmopolitan.com/advice/health/how-to-improve-fertility

Always Have Safe Sex

Unless you know for sure that your guy is STD-free, condoms are your best protection against fertility threats such as chlamydia and gonorrhea. If left untreated, these bacterial infections can enter your uterus and fallopian tubes, where they morph into a more serious condition called Pelvic Inflammatory Disease (PID). Scarily, one in five women with PID end up infertile.

Caught early, chlamydia and gonorrhea can be easily cured with prescription meds. But not all women experience symptoms, such as a green-yellow discharge or burning and pain, so they don't know they are infected and never seek treatment. Bottom line: Be screened after any incidence of unsafe sex as well as at your yearly gyno checkup, just to play it safe.

Learn How to Handle Stress

Ever have your period go MIA for a month or two when you were under a lot of pressure? Then you know how stress can mess with your cycle, preventing you from ovulating regularly. Science backs this up: A recent study published in the journal Fertility and Sterility found that women took longer to become pregnant if they had high levels of a stress-related enzyme. It's important to hone your relaxation skills now, so stress doesn't disrupt your cycle when it's time to join the motherhood club. Check out some great relaxing tips.

Stop Lighting Up

A lot of women don't consider themselves smokers because they're not addicted to nicotine, and they only puff every once in a while — say at a party or while hanging out with smoker friends. But occasional smoking harms your baby-making ability the same way a pack-a-day habit does. How? Toxins in smoke harm your fallopian tubes, cause chromosomal damage to your eggs, and impair your ability to produce estrogen, which prepares the lining of the uterus for pregnancy. Plus, smokers who do manage to conceive have higher miscarriage rates.

Don't Be Fat-Phobic

A little body cushioning keeps you fertile; if your BMI dips below 18.5 (20 to 25 is the healthy range), you'll probably stop ovulating because you don't have enough fat to support a pregnancy. On the other hand, don't go overboard and use your future status as a mom as an excuse to pack on pounds and indulge in junk food. Being obese (aka, a BMI of 30 or higher), means you likely have a higher number of fat cells throughout your body, which can make ovulation irregular. Calculate your BMI here; if it's too high or low, start shoring up your eating habits.

Ease Up on Your Seafood Intake

Shark, swordfish, and mackerel typically contain high levels of mercury, which is associated with infertility, miscarriage, and birth defects. Since it can take over a year to get any mercury you've ingested out of your system, avoid these options well before you're ready to conceive. Of course, don't give up fish altogether; it's packed with protein and other essential nutrients. Just stick to two meals a week of low-mercury seafood like shrimp, salmon, and light tuna. If you're unsure of your levels, check this online mercury calculator.

Find Out if Your Mom Had Fertility Issues

Her sexy curves aren't all your mother may have passed down to you. Infertility-causing diseases and conditions like endometriosis, polycystic ovary syndrome, uterine fibroids, and early menopause all have a strong genetic association. Knowing if they run in your family means you can seek treatment before you find out the hard way that you may not be able to conceive or carry a baby.

On the upside, you don't have to worry if your mom had a miscarriage (or several). "Most miscarriages are random events and they happen to women of all ages, so there's no genetic predisposition," says Dr. Guy Ringler, a fertility specialist at California Fertility Partners in Los Angeles who also serves on the Board of Directors at the American Fertility Association.

Don't Panic About Being on the Pill

There's a myth out there that taking oral contraceptives, especially for years on end, can make it harder to conceive when you go off the Pill to have a kid. Don't believe it. "Birth control pills have no negative affect on future fertility," says Dr. Ringler. Most women who had a regular cycle before taking the Pill will be fertile as soon as they go off it and get their period within one to three months.

Watch the Calendar — Especially if You're Over 35

It's smart to postpone babymaking until you feel ready for it. But don't put it off too long. No matter how healthy you eat or how many times you go to yoga class, your biological clock continues to tick. You're born with about one million eggs, but as you age, they die off; by your mid-30s, you're down to 30,000. Meanwhile, the risk of miscarriage and genetic diseases such as Down syndrome go up with age. For women under 30, it's estimated that the chance of getting pregnant in any one cycle is 25 percent. By age 40, it falls to 5 percent, according to the American Fertility Association.