I’m going to say boy based off the skull. It’s hard to look at the nub because it could easily be the cord

I only knew by my son’s nub at 13 weeks because the tech zoomed in and it was clearly boy parts ?

That's What I was Thinking Girl Based Off Heart Rate But Boy Based Off Skull Theory

Even though its an old wives tale, my first girl had high 150’s. My second kid (boy) averaged 140-150 most doc visits. Im preggo now woth my third and its a gitl and when i saw my doc last firday the heart beat was 156.