In a word, coffee is a mostly good way to cope with the daily stresses of parenting — but also a potential barrier to becoming a parent. Here’s the data behind these conclusions.

When Mom Drinks Coffee, Baby Gets Fat

When pregnant people drink more than one cup of coffee per day, their children are more likely to be overweight at 8 years of age, according to a study of 51,000 Norwegian mothers and their children. The data below illustrates the study’s key findings. “Any caffeine consumption during pregnancy is associated with a higher risk of excess infant growth and of childhood overweight, mainly at preschool ages,” the study authors concluded. “This study adds supporting evidence for the current advice to reduce caffeine intake during pregnancy.”

Higher Caffeine Intake, Higher Risk Of Stillbirth

More dire than obesity, however, is the data suggesting that excessive caffeine consumption during pregnancy can increase the risk of stillbirth. One particularly compelling offering, published in 2010 and summarized below, surveyed more than 2,500 parents and concluded that “greater caffeine intake is associated with increases in late miscarriage and stillbirth” (although the authors cautioned that their work did not prove that caffeine causes stillbirth).

Dads Need To Kick Their Coffee Habits, Too

There is a growing body of evidence that men can mess with their sperm (and, by extension, their future offspring) by drinking alcohol, taking drugs, or failing to exercise regularly. Several studies have specifically examined how men’s coffee habits impact their sperm count and quality — and it ain’t pretty. One of the most robust papers on the subject, published in 2010, concluded that, at the very least, one “cannot exclude the possibility of a threshold above which cola, and possibly caffeine, negatively affects semen quality.” When one examines the data, two conclusions jump off the page. First, Danish men drink a lot of coffee. In a random sample of 2,500 Danish men, more than 700 reported drinking 8 or more cups of coffee per day! Second, and more to the point, excessive coffee drinking could really do a number on your swimmers.