Woman wanting to get pregnant can take a blood test that measures their remaining pool of eggs.
Every woman is born with a finite number of eggs, and as she grows older, the number of eggs she produces begins to dwindle.
"That's a biological phenomenon that nobody really understands," said Dr. Kenneth Gelman, a reproductive endocrinologist. "It's just do to reproductive aging as we call it."
The blood test measures anti-mullerian hormone levels, and can determine the remaining pool of eggs.
"When a woman experiences this problem and we measure this level, it hits home rather hard," said Gelman.
Gelman said a low AMH level doesn't mean a woman can't get pregnant, but it may mean she needs to take aggressive measures to push the process along.
"If a particular woman comes in and her AMH is low, I would tell her in three to six months, you should try to get pregnant," he said.
Rachel Lanza was in her 20s when she and her husband decided to have children. She never imagined it would be a struggle.
"I was like, 'No, I'm good. I'm young. I'm fresh,' and it wasn't like that," she said.
Lanza was stunned to learn her levels were low at the age of 27.
"When I saw the results, I was like, 'I don't have that much time,'" she said.
Lanza used in vitro fertilization to get pregnant with her daughter Mia.
"I'm glad I did it because even when I went aggressive, it took me three years," she added.
Doctors advise women wanting to get pregnant have their AMH levels retested because in rare cases they can drop unexpectedly.
Studies have shown smoking speeds up the depletion of eggs and causes premature aging of the ovaries by one to four years.