My oldest is 24 and my youngest 17; I also have 6 grandkids from my step kids. All these pregnancies have had roughly the same timeline for appointments as the OP questioned. What did change from one to the next to the next was the frequency of ultrasounds. None for my eldest (or any of my step kids); that OB only did ultrasounds if there was a concern based upon other monitoring and tests. With younger son it was 1 ultrasound at about 6 months. With my grandkids, they have all had several ultrasounds at varying points during the pregnancy.