A Time article states the obvious:
A study published in the journal Pediatrics finds that men who become fathers around age 25 see a 68 percent increase of depression symptoms over the first five years of being dads—if they live at the same home as their children.
I became a father when I was 26 and it was a quite a bummer because I was used to getting all this attention from Judy and it all ended quite abruptly. We had been counseled about the transition but nothing quite prepares you for the way a baby consumes a mother's life.
The temptation for a mom to place her children ahead of her husband exists in every culture but I believe it's worse today because moms are more isolated from community than ever. It's not good for civilization. Books and on-line forums have replaced grandma and other traditional forms of social support. Moms need other moms (especially older ones) whom they can lean on to support each other. Dads need to set boundaries around the marriage, no matter how much moms might protest. If you protect your marriage, you will protect your kids. There is no greater witness to children and the world than a healthy marriage.
As a side note, the actual rate of depression is only 5 - 10% so it's easy to see 68% and think a young dad has a 2 out of 3 chance of getting depressed. That's not correct. A young man is 68% more likely to have depressive symptoms when he becomes a father living in the same home with his children as compared with similar-aged men who were not fathers.
Moms and dads both suffer when having a child but it's temporary and it changes the way you experience grace. For high-achieving people, having a child shows how little control we have over anything. We simply don't have as much as influence over our kids as we'd like to think. The first five years of Caleb's life were miserable and lonely for Judy and me. We both felt alone and it didn't help that I was working full-time, going to seminary, serving in the church, and trying to be husband and father to young kids.
Yet God used that time to really break us and help us understand grace. We have grown so much spiritually, made our marriage a priority, and today our kids are a joy and delight (it helps so much once they're out of diapers and don't need to nap). So it is possible to get through this - and be better off for it.