The visit schedule is mostly tradition
Twelve to fourteen visits is not an evidence-based number.
The standard American schedule, roughly monthly to 28 weeks, then every two weeks, then weekly, adds up to about 12 to 14 visits. It dates from the 1930s. The researchers who ran the largest US trial of an alternative model described the standard schedule bluntly as "expensive and resource intensive, with limited evidence supporting the structure, rhythm, or components of care."
That does not mean fewer visits are safe. A review of 7 trials covering more than 60,000 women found that reducing the number of visits was associated with more deaths around the time of birth, not fewer: relative risk 1.14, right at the edge of statistical significance. The signal came mainly from lower-income countries where the reduced schedules were much shorter. In high-income countries no clear difference was found, but the numbers were small.
A separate analysis of one of those trials found fetal death in 1.4% of the reduced-visit group against 1.1% of the standard group, with the excess concentrated between 32 and 36 weeks.