Rachel Weisz is pregnant at 48 and people are confused

Rachel Weisz, 48, is expecting her first baby with husband Daniel Craig, 50, and people can’t get over her “advanced age.”

The actress shared the news Friday during an interview with the New York Times when asked how she maintains her beauty. “I’ll be showing soon,” she answered. “Daniel and I are so happy. We’re going to have a little human. We can’t wait to meet him or her. It’s all such a mystery.” The couple have children from previous relationships — Weisz’s 11-year-old son Henry and Craig’s 25-year-old daughter.

The news spread fast online where excitement turned to shock, disbelief, and even disapproval over Weisz’s age.

“It is absolutely possible for a 48-year-old woman to get pregnant naturally — it’s just very unlikely,” Zev Williams, M.D. associate professor of obstetrics and gynecology at Columbia University Medical Center, tells Yahoo Lifestyle. “In fact, women over the age of 40 have high rates of unintended pregnancies due to taking fewer precautions on the belief that pregnancy isn’t possible.”

Generally speaking, a woman’s chance of conceiving drops around age 42 and 43. “It’s not that fertility disappears at a certain age, but rather the decline is a gradual process,” says Williams. “For a 28-year-old woman, about 25 percent of her embryos are chromosomally abnormal and for a 44-year-old woman, that number rises to 90 percent.”

He adds, “A 20-week-old fetus has its peak number of eggs.”

Given a 45-year-old woman has less than a one percent chance of getting pregnant using her own eggs, it’s possible that Weisz had fertility assistance — in vitro fertilization (IVF) is a process that involves extracting eggs and sperm from a couple (or from donors), combining them in a laboratory, and then transferring them to the uterus. She also could have frozen her eggs years prior, then thawed, fertilized, and transferred them to her uterus. “In that case, a 48-year-old woman could use her 30-year-old eggs to conceive,” says Williams.

Still, pregnancy is challenging on a 48-year-old body, so however she got there, Weisz is considered “high-risk” and more likely to develop conditions such as preeclampsia, which according to the Mayo Clinic is marked by high blood pressure and organ damage, gestational diabetes, and conceiving a child with genetic disorders such as Down syndrome.

And although Daniels is 50, his age is less relevant due to the fact that men can produce healthy sperm throughout most of their lives, says Williams. “It only takes sperm about three months to mature.”

Read more from Yahoo Lifestyle:

• Cardi B Explains Why She Kept Her Pregnancy a Secret

• Jessie James Decker — and her insane eyelashes — welcomes baby number three

• The problem with celebrity baby Instagram accounts, like the one for True Thompson

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