There is another reason. The statistical basis for US maternal mortality calculations is fucked up. Zum beispiel:  Using the number of live births as the base for MMR calculation, while the death count is calculated based on the number of pregnancies, which is a larger figure. Including death from all causes, not just medical pregnancy. A woman who died in a house fire within a year of giving birth is considered a case of maternal mortality, despite the fact that dying in a fire has nothing to do with maternity whatsoever.  There are other errors, but each error inflates the maternal death count.