Obstetrician makes bizarre discovery after woman just went through 40 hours of labor

A handsome son

Nicole had to get back to work. Her epidural had already worn off, so the pushing hurt a lot this time. But she did it! Exactly 59 minutes after the birth of their first child, their daughter Blakeley Faith, their son Cade Matthew Ziesemer was born. He was born at 11:05 PM. Baby Cade weighed 2265 grams, meaning the twins weighed 4260 grams together. This was a healthy total weight for twins.  

But how was it possible that Nicole never knew she was carrying twins until the very last moment? Why hadn’t the medical staff noticed this? Matt and Nicole had tried to keep medical exams to a minimum during the pregnancy, as they wanted to keep it as natural as possible, but that didn’t explain why it hadn’t come to light during the ultrasound.