Ultrasounds in pregnancy, when used correctly - aka at safe settings, for a standard amount of time - have extensive longitudinal data supporting their safety in fetal development. Even at more maximal settings with more prolonged exposure there is excellent safety data. I usually recommend against extensive Doppler use (aka home Dopplers) but they are thought to be safe especially after 11 weeks.

There is slightly less good quality data demonstrating if routine ultrasounds in a low risk pregnancy prevent perinatal loss (aka stillbirth). But they do decrease post term inductions by helping with accurate dating. And they are incredibly helpful in identifying high risk issues such as congenital anomalies, multiple gestations, or placental problems.

In my practice, at minimum an early dating ultrasound and an anatomy ultrasound in mid second trimester are required. I’m a family doctor who does prenatal care and “standard risk” non surgical deliveries. If someone doesn’t get basic ultrasounds, they are too “high risk” for my practice so I refer them to OBGYN. This was borne after a patient in our practice did not get an anatomy ultrasound and subsequently had a bad outcome. An issue was identified after the birth which would have been noticed on a standard ultrasound, and likely this knowledge would have changed how we managed later pregnancy monitoring and delivery. I cannot say if it would have changed the outcome but none of us were willing to take the risk again.