Concerned about risks with ultrasound

I have my second ultrasound scheduled on Wednesday when I will be 9w3d. I have private healthcare and they urge me to come in as often as possible as they make money off of me - they are recommending every 2-3 weeks. In Sweden, where I come from and healthcare is financed by the tax payers, low risk pregnant women only get two ultrasounds during the whole pregnancy. 
I have read that there are theories that the increased use of ultrasounds may/can be harmful to the fetus. 
Please share your thoughts on this and how you are deciding. 🙏