The pair are now 19 and 21 weeks along, and are excited to reunite around Christmastime, when they will enjoy milestones in their pregnancies together.
This woman wanted to surprise her sister while announcing she was pregnant, but she was the one who wound up surprised as it was revealed she wasn't the only one.
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Mommy vlogger Tara Brough, 26, wanted to announce her pregnancy to her older sister by having her open the oven to find a hot dog bun, a play on the phrase, "a bun in the oven."
"They weren't as excited," Brough told InsideEdition.com. "She had a good idea. They had kind of seen me sick, and they knew I was trying to get pregnant."
So they continued on with their night until, on camera, Brough's older sister Carly Walter slipped in unexpectedly, "we went to our first [maternity] appointment last week."
In the video, posted to Brough's YouTube page, Broughington, she can be heard pausing, then doing a double take before she exclaims, "What? No way. No way!"
"I don't usually have reactions like that, I'm usually pretty reserved," Brough joked. "I truly had no idea. All my excitement came out."
Brough, who is now 21 weeks along, has since discovered she is pregnant with a baby boy, while her sister, at 19 weeks, is expecting a girl.
Despite fans joking that the two sisters will be able to share their pregnancy milestones together, Brough said she and her husband moved up to Trovo, Utah, shortly after the announcement, while her sister Walter and her husband stayed in Mesa, Arizona.
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"I've been sad because we won't actually be able to be pregnant together except at Christmastime," Brough said.
But, the mother-of-three has been determined to help her older through her first pregnancy despite the distance: "I've been trying to keep her hopes up during the sick days, and calm her down [when she's worried] by saying, 'it's normal, it's nothing.'"
Watch: Man Surprises Wife With Pregnancy Despite Vasectomy Months Before: 'God Had Other Plans'
