We've all heard the stories - your wife is pregnant, so you gain a little weight - maybe have a few sympathy pains. But those stories aren't just "wives' tales."
A new study finds that men go through real, verifiable, biological changes when their partner is pregnant. Apparently, it's nature's way of making them better fathers.
It's a Sunday afternoon in the cramped basement where Melanie Headley holds her natural child birth class. All of the young couples are first-time parents -- and while the changes the women are going through are obvious to anyone, the men here are also experiencing psychological changes. Some they don't even realize.
In a recent study, first-time fathers were given weekly blood tests with their wives and the blood analysis was startling. Just like the expectant mothers, the dads saw documented changes -- namely, a lowering of testosterone and a spike in a hormone called prolactin.
The hormonal shift that most men experience when they become a father causes very real symptoms.
Typically, expectant fathers gain weight; usually as much as 10 percent of their body weight. The loss of testosterone lowers their sex drive, making them less competitive and less likely to stray from their partners. A spike in prolactin acts like an opiate, arousing tender and protective feelings toward their spouse.
After hearing about the results of the study, it was like a light bulb went off for the men in Headley's class. When they thought about it, almost all admitted they worried about their wives like at no other time in their relationships.
"I worry about even silly things, like her picking up stuff. I don't want her to injure herself or hurt the baby," said one man.
"I know she's an adult; she can take care of herself. Yeah, I definitely feel more protective," another added.
"We have a routine. And when we step out of that routine, it makes me worry that something happened and makes me want to check and make sure everything is alright," said a third.
Another male symptom is phantom pains - experiencing cramps, backaches, even foot swelling just like the women.
"I've been getting more leg cramps recently and I think he's been getting them too. So, we thought maybe that was because of the syndrome, but we didn't know," one man said.
Melanie Headley has been teaching this class for years and has four children of her own. The results of the recent study came as no surprise to her.
"The changes that she's having in her body biologically are going to take a toll on her husband as well," she said. "They're going to go through the same type of cycles, and they're going to synch up - I believe in that."
Copyright 2012 America Now. All rights reserved.