Jean Twenge is a researcher by trade, so when she started trying to get pregnant at age 34, she turned to original research materials.
There, the San Diego State University psychology professor told KPBS, she found valuable information about infertility and age.
"That it wasn't as scary as you might have thought," she said.
She also found information on how to get pregnant faster, began sharing it with her friends and then decided she might also want to share it with a wider audience. So she wrote a book, "The Impatient Woman's Guide To Getting Pregnant."
The Centers for Disease Control says about one-third of couples in which the woman is older than 35 years have fertility problems.
That's because women are born with a set number of eggs, said Dr. Sanjay Agarwal, a clinical professor and Director of Fertility Services at UC San Diego.
"With time, that number goes down," he said. "And as that number of eggs goes down, their fertility goes down, and that's what eventually leads to menopause in their 50s."
But, he said, it's not a black-and-white situation, because fertility goes down gradually.
"From the mid 30s, 35, 36, 37, fertility goes down a bit quicker," he said.
But Twenge said the statistic that one-third of women over 35 will have fertility issues is based on birth records from the 1700s.
"We don't have enough good data on natural conception, so a lot of times the biggest studies are from historical birth records, but of course things are a little different now," she said.
She said more recent studies suggest 82 percent of women will be pregnant after a year, even if they're over 35.
Agarwal agreed that the CDC number was "a little high."
He said he recommends six months of trying to get pregnant if you're over 35, 12 months if you're under 35, "so you don't spend too long before seeking help."
