15 weeks and 4 days !

Does anyone remember their baby’s heart rate at around 15 weeks ? I got my ultrasound done at 15 weeks and 4 days to try to find out the gender and she told me it was a girl and that the heart rate was 138 but that seemed kinda low to me so I was just wondering if anyone else’s baby had a heart rate this “ low “ around the same time ? I know every baby and pregnancy is different but I was just wondering !