Brooks and Nolan Bauer, a rare set of "momo" twins, are finally home with their parents in White Marsh.

"They were really premature, eight weeks early," Katie Bauer said Saturday, recounting the first time she saw her sons. "They told us they might be on respirators and things like that … but they only had these little tubes in their noses and were getting room air."

Bauer, 27, gave birth Feb. 13 to the extraordinary boys, who, like other momo twins, grew in the same fetal sac. Tests to check their development are the only reminder of the threats the boys faced for seven months in the womb.

"Momo" is derived from the words that describe Bauer's pregnancy.

"Monoamniotic" means the twins are identical and share an amniotic sac. "Monochorionic" means they also share a chorion, a membrane that surrounds the sac and contributes to the formation of the placenta.

It's a situation that arises only once in every 10,000 pregnancies, according to Dr. Claire Weitz, an obstetrician and gynecologist for high-risk pregnancies. She oversaw Bauer's care.

Momo twins face serious danger. By developing in the same sac, they are exposed to each other's umbilical cords, which frequently become entangled and compressed. That can cut off the supply of oxygen and nutrients to one or both fetuses.

Medical journals report that entanglement is observed in more than 40 percent of momo pregnancies. One study, from 2010, concluded that when momo babies are routinely evaluated with specialized sound-wave scans, it is apparent at some point in the pregnancy that the umbilical cords have become snarled.

"The game plan changed completely when we found out they were monoamniotic," said father Shane Bauer, a 28-year-old software developer.

The couple had known since August that they were expecting twins but didn't find out until after Thanksgiving that there was no membrane separating the boys.

They had been expecting a full 40-week pregnancy, said Katie Bauer, who taught preschool until December. But because of the high potential for cord entanglement, doctors suggested scheduling a Caesarean section at 32 weeks, with Katie Bauer spending at least a month at Greater Baltimore Medical Center before delivery.

Upon arrival at the hospital in January, she was immediately bombarded by tests to monitor the babies' health, the couple said by phone. The sonograms and other tests were constant — at least three a day — until the delivery.

"I wasn't on bed rest, but I was mostly confined to my room," Katie Bauer said. "In between [tests] I would sleep because I was exhausted."

When she was not asleep or going through a battery of tests, she was blogging on her website, "My MoMo Boys."

Because momo pregnancies are so rare, the Bauers said, they had a difficult time finding resources to learn about their situation. Outside of a Facebook group and a Wikipedia page, there is little information about momo development to be found on the Internet, the couple said.

"I want to track my progress for all these women with momo babies," Katie Bauer said. "Because these women have nowhere to turn to."

She shares her anxieties and emotions on the blog, including this excerpt from a Jan. 15 post called Last Day at Home: “I'm trying to relax and pretend it's like a normal day but it's hard knowing I won't be here for awhile. I hate hospitals, but I know I'm doing this for my boys. I'm just having a weird mix of emotions -- I hate the idea of being there, but I can't wait to be there and be able to have the boys monitored a few times daily.”

In a Jan. 28 post titled Nervous, she said: “Today would have been my baby shower, which kind of made me sad. Not sad, because things are going well. But I got a little upset when I realized it because I remember thinking back to the very beginning of the pregnancy when I was happy and getting excited for all the fun things to come. It's so frivolous in the whole grand scheme of things: the shower, and preparing the nursery, and getting excited about sonograms; but, they are all things I looked forward to when imagining myself pregnant. Now all I want are my babies.

And in this March 12 post, she described having to take Nolan home first, and having to leave Brooks for a few more days in the neonatal intensive care unit: “I think that after the pregnancy -- wondering if the babies were alive everyday, this was the hardest part of the whole experience. It was heartbreaking leaving Brooks there alone. I felt terrible separating them. I know it's for the best, and Brooks still needs to be there, but he's always been with his brother.”

She's hopeful her words will give comfort to mothers facing the uncertainty of a momo pregnancy.

"Compared to a lot of [momo] babies, our babies were amazingly lucky," she said. "I still can't believe how lucky we are."

steve.kilar@baltsun.com

twitter.com/stevekilar