Although many parents happily take to their new role, millions every year respond with despair. According to a 2010 article in the Journal of the American Medical Association, among new parents — three to six months postpartum — 42 percent of mothers and 26 percent of fathers exhibit signs of clinical depression. In a longitudinal study reported earlier this year in the journal Pediatrics, men on average experienced significant increases in depressive symptomatology across the first five years of fatherhood (if and only if they lived with their child). Indeed, in the years after becoming a parent, both men and women experience significant reductions in their overall level of satisfaction with their lives, according to a 2008 paper in The Economic Journal.

The story is similarly bleak when we look at people’s day-to-day experiences. In a study published in the journal Science, people reported their emotional experiences during each of 16 activities over the course of the previous day: working, commuting, exercising, watching TV, eating, socializing and so on. They experienced more negative emotion when parenting than during any activity other than working. And they experienced more fatigue when parenting than during almost any other activity.

Parenthood takes its toll on your relationships as well. A 2009 study in the Journal of Personality and Social Psychology found that the transition to parenthood is linked to reduced happiness in the marriage and more negative behavior during spousal conflict. Evidence also demonstrates that this transition is connected to substantial reductions in the size of a parent’s networks of family and friends.

This research, which doesn’t even touch on the staggering financial cost of raising a child, provides clear evidence that for many people becoming a parent is one part blessing, one part trauma.