MINNEAPOLIS (WCCO) – We all know exercise is good for us, but can it be too much of a good thing? Some doctors say it can be, when it comes to getting pregnant.

A recent study showed that women who were active most days of the week were three times more likely to have fertility problems compared with inactive women, regardless of their weight.

When Chanhassen residents Taylor and Derek Pederson suffered two miscarriages–one at eight weeks and another at six–doctors couldn’t figure out what was wrong.

“We were told this just happens sometimes, it’s a fluke,” Taylor Pederson said.

Taylor, who’s done Taekwondo for 14 years, started doing her own research. She wondered if her fitness habits were affecting her fertility health.

“I’d heard that extreme working out could affect your ability to get pregnant,” she said. “I never put myself in that category.”

Taylor was at a healthy weight, active most days of the week.

But she decided to cut down on exercise, going from six hours weekly to practically nothing.

Nine months later, they welcomed their daughter Avery.

“I don’t think they realize you can go overboard, and there’s a balance to everything,” she said.

Infertility specialist Dr. Philip Marcus said having low body fat and exercising excessively can sometimes cause fertility problems, but he said typically the person is also underweight.

“You need a certain amount of body mass to have your ovaries listen to your brain and ovulate correctly,” Marcus said. “Body fat is related to it, but you can’t tell by just looking at somebody.”

He said in extreme cases of physical activity, pregnancy can be more difficult; marathon runners or gymnasts may struggle.

Their extreme training lowers their body fat, he said, and “for that particular person, a lot of times it just isn’t going to work.”

So for the average individual at a healthy weight, working out shouldn’t hurt.

But if you’re pushing yourself daily, or for hours at a time, and you have low body fat, then you may want to ease up for a healthy pregnancy.

Taylor Pederson said she has started getting back into Taekwondo  and will be testing for her black belt in June.

She also said she’ll stop exercising when she and her husband are ready to have another baby.

Kate Raddatz