The first thing is to consult with the obstetrician whether or not you can do pilates during pregnancy (even if you already practiced pilates before becoming pregnant) and when you can start practicing pilates during pregnancy.
When medical consent is obtained to do pilates during pregnancy, the most widespread recommendation is to do 2-3 classes a week of prenatal pilates with a professional who adapts the exercises to the pregnancy and the period of pregnancy in which the woman is and also supervises that they are being done correctly.
The duration of the classes is usually between 45-60 minutes. However, if the woman has been authorized by the medical specialist that she can do prenatal Pilates from the first trimester, the duration of the sessions will probably be less until the pregnancy is more advanced.