The reason you had no idea about this is because it's complete bullshit. Of course other first world countries don't count it differently just to make the numbers sound better.
Because even with that, related normalized numbers are still shit. It's not just some counting problem.
"Women in the U.S. have long had the highest rate of maternal mortality related to complications of pregnancy and childbirth. In 2020, there were nearly 24 maternal deaths for every 100,000 live births in the U.S., more than three times the rate in most of the other high-income countries we studied"
"The U.S. infant mortality rate (5.8 deaths under one year of age per 1,000 live births) is 71 percent higher than the comparable country average (3.4 deaths)"
