Growth Worry- help!

knottieae02a34a1fbbc943

Hi all! First pregnancy here. I had an ultrasound a couple weeks ago where they measured baby at 6 weeks 2 days, heartbeat at 109bpm. Exactly 1 week after that, doc measured baby at only 6 weeks 5 days, but heartbeat went up to 129bpm. He said that I'm at a higher chance of miscarriage now especially being 41. And basically said nothing else but wait and see in a week. Thankfully my husband was there and told me the measurement process looked pretty rough and tried to reassure me, but I'm still freaking out a bit. Is my husband right? Trying to stay calm before the next ultrasound.