Halle Berry's pregnancy was a "surprise." What are the odds?

Halle Berry is as shocked about her pregnancy as everyone else.

"This has been the biggest surprise of my life to tell you the truth," Berry told CNN on Monday. She added: "I feel fantastic."

Berry, who confirmed her pregnancy to press on Friday, revealed that it just, well, happened the old fashioned-way—no planning involved. Have we mentioned she's 46?

"I thought I was kind of past the point where this could be a reality for me," said explained. "So it's been a big surprise and the most wonderful."

Berry already has a 5-year-old daughter, Nahla, with her ex-boyfriend, Canadian model Gabriel Aubry. This baby-on-the-way is her first with fiance Olivier Martinez, 47, whom Berry has been dating since 2010.

Considering how much pressure women face to beat their own body clocks, it's shocking to learn that we can still get pregnant late into our 40s without even trying. Then again, this is Halle Berry—a woman who defies all logic of aging.

So what are the odds? Late-in-life pregnancies actually happen more often than one might think. Women start gradually producing less estrogen in their 40s, but perimenopause (the stage before full-on menopause, when you stop ovulating) can start in your 30s or even earlier. It causes irregular periods and a decline in fertility, which leads many women to assume -- as Berry did -- that they're simply too old to get pregnant.

"As ovulation becomes irregular, your ability to conceive decreases. However, as long as you're having periods, pregnancy remains a possibility," the experts at the Mayo Clinic explain. "If you wish to avoid pregnancy, use birth control until you've had no periods for 12 months."

IVF and other fertility treatments have allowed women to become moms much later in life, but while 46 is on the late side for a naturally conceived surprise pregnancy, it has been known to happen even later. In 2011, Anthea Nicholas of Queensland, Australia, became a new mother at age 50 -- without infertility treatments.

Berry is reportedly just three months along; according to TMZ, the actress was feeling sick and complaining that she had gained a little weight in late February, when she appeared at the Oscars in a body-hugging metallic-and-black dress by Versace -- which hinted at a tiny bit of a belly.

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