first time

first tri 1-3months (4weeks - 12weeks) 2nd tri 4-6months (13weeks - 24weeks) 3rd tri 7-9 months (25 weeks - 36 weeks) 9 mos and 3 weeks ( 37 weeks - 39 weeks) 10 months (40weeks - 42 weeks) overdue

First trimester is first 3 months (13 weeks) of pregnancy.