An elderly woman in Brazil recently found out that her stomach pains were a sign of something other than indigestion. According to USA Today, the 84-year-old woman from the central Brazilian state of Tocantins was actually carrying a 44-year-old “stone baby” in her abdomen.

The woman was hospitalized last week with what were described as intense stomach pains. X-rays revealed that the woman was carrying a fetus that had calcified in her gut over 40 years earlier, a condition known as a lithopedion baby.

"Through ultrasound it was not possible to see the fetus,” Gesneria Saraiva Kratka, a gynecologist at the Porto Nacional hospital where the woman was treated, told G1 News. “We saw it with x-rays. It was possible to see the face, the bones of the arms, of the legs, the ribs and the spine."

According to reports, the 84-year-old woman recalled being pregnant more than 40 years ago, but lost the baby after suffering pain during the pregnancy. When she saw that her stomach didn’t grow anymore, and that the baby had stopped moving, she assumed the fetus had been “aborted.”

Lithopedion occurs when a fetus begins to grow outside of the mother’s uterus and in the abdomen. This is a form of ectopic pregnancy, where an egg is fertilized and begins to develop in places it should not, such as the ovary, the fallopian tube, the bowel or even the aorta.

While ectopic pregnancies are fairly common, occurring in about one in every 11,000 pregnancies, lithopedion happens in just 1.5 to 1.8 percent of these, according to the Sao Paolo Medical Journal. Since the late 16th century, there have only been about 300 cases of "stone babies" reported in medical journalism worldwide.

When a fetus develops in a mother’s abdomen, the body’s response is to calcify the fetus in order to protect the mother from infection. Women who carry a lithopedion baby tend to be over 40, but the condition can occur in women as young as early 20s.

In Dec. 2013, a woman in Colombia also discovered a calcified baby in her abdomen that had been there for 40 years. The fetus weighed four pounds and was surgically removed from the 82-year-old woman’s body.

According to Yahoo Health, the woman in Brazil refused to have doctors remove the stone baby from her stomach.