Twins are rare, occurring in roughly 2 percent of all pregnancies. Of those, monoamniotic twins—in which the babies share both a placenta and amniotic sac—are even more uncommon, happening in fewer than 1 percent of all instances of twins.
But what makes an Iowa woman's pregnancy absolutely singular is that she was pregnant with monoamniotic twins without knowing it. As WHOTV reports, Shelby Magnani was having stomach pains, particularly a "sharp pain" on her left side, so she went to a walk-in clinic.
"They said, 'We think you might be pregnant,'" she tells the station. "They told me I was six months [along] and told me to get down to the ER" for an ultrasound.
That's when the Ankeny woman and fiance James Croskey learned it was twins. This type of pregnancy is highly complicated: The mortality rate is about 50 percent, with the biggest worry being that the umbilical cords could get tangled in such a small space—the Children's Hospital of Wisconsin likens the cords to a garden hose, explaining that if they "flatten or bend, the supply line can be damaged or cut off," impeding development or even causing death.
Dr. Jennifer Krupp explains that "we bring the patients into the hospital at 24 to 26 weeks, so we can monitor the babies several times a day." But as WHOTV reports, Magnani "missed out on the worst part of having monoamniotic twins: the worry." How fast it happened: On Oct. 6, Croskey posted on Facebook that he was throwing a huge Halloween party; three days later, he posted a request for a ride to Mercy Hospital—followed by an album of his girls.
The identical Ava and Anna entered the world via C-section on Thursday, weighing 4 pounds, 6 ounces and 3 pounds, 12 ounces, respectively. Though they'll need to stay in the NICU, they're expected to be fine.
(Another woman recently gave birth hours after learning she was pregnant.)
This article originally appeared on Newser: Woman Doesn't Know She's Pregnant, Births Rare Twins
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