Oliver James Montgomery-Alabama woman pregnant with 2 babies in 2 uteruses gives birth ahead of Christmas

In what some may call a Christmas miracle,Oliver James Montgomery an Alabama woman born with two uteruses has given birth to twin girls on different days.

Kelsey Hatcher learned of her condition, known as uterus didelphys when she was 17 years old, but it would be another 15 years before it resulted in her one-in-a-million pregnancy. Uterus didelphys is so rare it occurs in less than 1% of all women.

The 32-year-old and her husband, Caleb Hatcher, live in Dora, Alabama, outside of Birmingham. The couple welcomed twin girls 10 hours apart at The University of Alabama at Birmingham Hospital, according to a press release.

Double the labor

For Hatcher this rarity "meant double the uterus, double the labor, double the babies and double the birthdays," the release said.

'One in a million':Alabama woman pregnant with 2 babies in 2 uteruses due on Christmas

"Our miracle babies were born! They decided they were rare enough statistically that they should just go ahead and have their own birthdays too. Roxi Layla was born Tuesday night 12/19 at 7:49pm and was joined by her sister, Rebel Laken, Wednesday morning 12/20 at 6:09am," Hatcher announced in an Instagram post.

In all, Hatcher spent 20 hours in labor.

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Hatcher is already a mother to three, and she was not expecting to have additional children until she learned she was pregnant in May.

"There’s only one baby in there, right?" Hatcher joked with her doctor at her first ultrasound at eight weeks.

"As soon as she moved the ultrasound wand across my belly, I said, 'Oh my gosh, there’s another one. Oh my gosh.' She said, 'Yes! There is,'" Hatcher told "TODAY." "I was just in complete shock and think for the first, I don’t know, two to three weeks, my husband and I just laughed."

A one-in-a-million pregnancy

The pregnancy is "one in a million," Dr. Richard Davis, a physician at the hospital where Hatcher delivered her children, told WVTM-TV in Alabama.

Hatcher's pregnancy is so uncommon, that "some OB-GYNs go their whole careers without seeing anything like this," Dr. Shweta Patel, Hatcher's OB-GYN, previously told the outlet, calling her circumstances "very, very rare."

Hatcher's pregnancy is a first for the team at the hospital. They're relying on "baseline teaching and baseline knowledge," Patel told "Good Morning America."

While twin pregnancies aren't rare, Hatcher's pregnancy and birth are uncommon because she ovulated separately, with each egg traveling down each side of the uterus and the sperm traveling up each uterus, and fertilization occurring in both.

"Because my cycles have always worked together as one, I assumed as I ovulated on one side ... and there would be no chance of having a baby in the opposite uterus," Hatcher previously told USA TODAY. "I never would have thought I would ovulate from both at the same time."