Quoting BabyMamax5:" Ok so is everyone going by 13wks or 14wks for their 2nd tri? I keep getting conflicting info on what week it should start..."
Pregnancy is measured in trimesters from the first day of your last menstrual period, totaling 40 weeks. The first trimester of pregnancy is week 1 through week 12, or about 3 months. The second trimester is week 13 to week 27. And the third trimester of pregnancy spans from week 28 to the birth.
This was on WebMD so this is what I'm going by. This is what my doctor with my son always said, too. Some people say it doesn't start until the end of your 13th week, but I'm gonna say my 2nd trimester starts Wednesday! Haha!