2: Three Trimesters
Pregnancy is divided into three trimesters mainly because it can be divided into nine lunar months, each lasting about 29.5 days. There are also distinct fetal developments during each trimester, which follows a predictable and measurable course, though measurements may be approximate and vary with each individual pregnancy.
Typically, Trimester 1 is calculated from conception to week 12, Trimester 2: Week 13-27 and Trimester 3: Week 28-birth.
Has your doctor explained the 3 trimesters and the stages of pregnancy ?