6 changes men can make to improve sperm and have a healthier baby

For women who are pregnant or trying to conceive, the warnings seem endless: Don’t drink! Stop smoking! Avoid caffeine! But what about dads? (After all, they are 50 percent of the equation.)

Recent studies indicate men’s health and habits pre-conception also impact babies for years to come, because things like alcohol and cigarettes can damage DNA within sperm. If one of those imperfect swimmers wins the race and fertilizes the egg, the baby’s genetic makeup can be compromised.

Trying to quantify just how much dad’s health affects children isn’t easy, though. “Women ovulate one egg, whereas men have so many sperm to choose from,” explains Caitlin Dunne, a doctor who specializes in fertility at the Pacific Centre for Reproductive Medicine in Burnaby, BC. “With that redundancy, there's still the possibility that there's a good sperm.”

Men can increase the likelihood of producing fit sperm by adopting healthier lifestyles. Sperm rejuvenate every 72 days, so Dunne suggests guys wait three months before trying to have kids for the changes to take effect. Here are some good places to start.

1. Lose weight We joke about dad bods, but men packing extra pounds may pass on an increased risk of obesity to their kids. That was the finding of a 2015 study from the Novo Nordisk Foundation Center for Basic Metabolic Research. Researchers compared the sperm of men who were a healthy weight to that of obese men and discovered differences in how cells read genes in each group. Their tests even indicated changes to sperm cell DNA after morbidly obese men underwent weight-loss surgery. These molecular changes might indicate that having an obese father can affect a child’s metabolism.

2. Quit smoking The sooner men butt out the better. In 2016, researchers from Norway’s University of Bergen discovered that children whose fathers smoked prior to conception (but not after birth) were three times more likely to have asthma than kids whose dads had never lit up a cigarette. The younger the father was when he started and the longer he smoked, the more likely the child was to develop the respiratory condition.

3. Stop drinking A 2013 study published in Animal Cells and Systems suggests moms’ drinking habits aren’t the sole contributors to fetal alcohol syndrome. In the lab, researchers exposed some male mice to alcohol and others to saline prior to mating. The fetuses from the “drinking dads” had abnormal brain and organ development, while the others were healthy. The researchers concluded that dads’ pre-conception drinking could alter genes in their sperm that impact fetal development.

4. Start young Women will no longer be the only ones to hear: “You’re not getting any younger, you know.” It appears similar risks for conceiving late in life exist for both moms and dads. An American and Swedish study published in 2014 found that, compared to children born to dads between the ages of 20 and 24, the offspring of men 45 and older were more likely to have autism, ADHD, bipolar disorder, substance abuse problems and failing grades.

5. Reduce stress If guys are totally stressing over the idea of becoming dads, they might want to find their zen. Research suggests that relieving stress could benefit future kids’ mental health. A University of Pennsylvania study from 2015 compared the offspring of mice that were exposed to stress pre-conception with the babies of those that weren’t. The mice with the stressed-out dads actually had a more numbed response to their own stress, producing less of the hormone corticosterone (like cortisol in humans) than the mice with chill dads. Responding to stress with abnormal amounts of these hormones could result in psychiatric disorders.

6. Cut back on caffeine Sorry, dads, but a 2016 study indicates that men should switch to decaf before trying to have kids. Researchers from the National Institutes of Health and Ohio State University looked at more than 500 couples and discovered the likelihood of miscarriage increases when both mom and dad consumed more than two caffeinated drinks a day in the weeks prior to conception.

Read more: How long does it take to get pregnant? Vasectomy reversal: What you need to know