Fetus Hiccups

Ek...Ek....Ek....lasted for about 10 minutes. That was what my girls were doing yesterday and again today. They were hiccupping!!! At first, I was so curious about the little rhythmic movement. It was very gentle and immediately I know it wasn't my baby kicking. Baby B had it first in the afternoon and at night before going to bed, it was Baby A's turn. And around 2pm today, Baby A was once again hiccupping. I've read that it is very normal that babies in the womb starts to hiccup as they are practicing breathing. However, some research papers mentioned that lots of hiccups a day (6-8 times) indicate problem, i.e., the u-cord is wrapping around the baby's neck. Well, I think I shouldn't stress up with this. I'm sure they are fine.