In a prospective study conducted in 2020 to 2021, macrolide resistance–associated mutations were found in 41% of pregnant persons in Birmingham, AL, with Mycoplasma genitalium detected. We retrospectively evaluated M. genitalium in 203 pregnant persons participating in a study conducted in 1997 to 2001 in Birmingham and adjacent areas and found a prevalence of 11% (95% confidence interval, 6.9%–15.7%), but no macrolide resistance–associated mutations.