Pregnancy might just be catching at a hospital in Mesa, Arizona, where 16 nurses are expecting at once.
That's 10% of the nursing staff in the intensive care unit, and patients have started to notice the high pregnancy rate, the nurses said.
At a news conference, the women joked that there must be something in the water, or that maybe it was a joint plan for Christmas holidays off.
The group's first birth is expected in September and the last in January.
Rochelle Sherman, who is just over a month away from giving birth, said: "I don't think we realised just how many of us were pregnant until we started a Facebook group.
"It's like we had some kind of pact going on."
Her colleague Jolene Garrow thanked colleagues who have stepped in to do jobs pregnant women cannot do - such as dealing with contagious illnesses like tuberculosis and shingles, or performing some treatments for cancer patients.
The staff will throw a joint baby shower for all the women next week, before they start going on their 12 weeks of maternity leave.