Sperm Killer #4: Overdosing on Coffee

A moderate amount of caffeine may make sperm happy by helping them swim to their target faster, but too much may do more harm than good. Limit your consumption to no more than the amount in two to three cups of coffee a day—and that includes sports drinks and supplements. Additionally, an addiction to coffee may mask another, larger problem. “Anytime you use coffee daily to compensate for low energy levels, you have to look at rest of your life and figure out why you’re tired all the time,” says Dr. Domar. 

Sperm Killer #5: Adding More Candles to Your Birthday Cake

It turns out that guys have a biological clock, too: It’s not just women who have a harder time getting pregnant in their forties. “The age of a man has a very real impact on his ability to get a woman pregnant, as well as on her likelihood of carrying to term,” says Dr. Domar.  The age of the father is also now linked to autism and schizophrenia. “Concern rises for guys over 40, and there’s a more significant impact with men over 50,” she says.

Sperm Killer #6: Double Fisting

“A daily glass of wine or cocktail may help keep heart disease at bay, but it’s bad for sperm,” says Dr. Domar, who recommends no more than five to seven drinks per week when you’re actively trying to conceive. It’s no surprise that drinking and smoking is twice as harmful to your swimmers. “If you look at the impact of alcohol and nicotine together, they can have a profound effect on sperm condition,” she says. That’s because nicotine has been shown to lower sperm count and quality, squashing your odds of making a baby.

Sperm Killer #7: Feeling Stressed

Men, too, can be affected by the stress of trying to have a baby. “For men, fertility is linked with virility and sexuality,” says Dr. Domar. Yet baby making can trigger anxiety when it starts to become an effort (think: ovulation tests and pressured sex sessions). Indeed, a recent survey sponsored by Merck found that even more men than women—42 percent versus 36 percent—said stress and tension in their relationship has increased while trying to have a baby. If this happens, try explaining to your partner that you’re just as excited as she is about taking this next big step and you want to give it your best team effort, but that stress can hurt your chances of conceiving. Then blow off steam by doing something together that you both enjoy. Once you’ve shared some fun, don’t be surprised if you end up right back in the bedroom.