At 28 weeks
But I go with 27 weeks because in reality you are pregnant for 3 equal periods of 13 and a 1/3 weeks (or 13 weeks plus 2+ days). That math will give you 40 weeks. So really at 26 and 2/3 weeks (or 26 weeks and 4/5 days) you are 2/3 of the way done. Conception to about the 12 th week of pregnancy marks the first trimester. The second trimester is weeks 13 to 27, and the third trimester starts about 28 weeks and lasts until birth. This slide show will discuss what occurs to both the mother and baby during each You are only technically pregnant 266 days if you go full term. The 280 days is full term plus 2 weeks prior to ovulation--when you weren't even pregnant. If you go by the 40 weeks (280 days) the prior poster is right. The math would be 13.3 weeks and you would be in your third about 27 weeks. If you go by 266 days, you would be starting your third trimester in the 25th week. So, docs go between 25-28 weeks for that reason. Why any doc would ever say that the third trimester starts in the 30th week is beyond me. The third trimester starts at 28 weeks and continues until the birth of your baby. This is the seventh month of your pregnancy and during this time the fetus grows larger and the organs begin to mature. During the second trimester, you will generally begin to feel the best that you will feel through your entire pregnancy. Your morning sickness is probably gone, as is the fatigue and lack of energy that characterized your first trimester of Finding a childbirth class, preparing for your maternity leave, and decorating the nursery are a few of your third trimester to-do's. Let us help guide you through your third trimester with our expert advice on everything from staying comfortable as your belly grows and to knowing when you're in labor. Pregnancy is an amazing process and the cycle of progression can be very exciting if this is your first baby. The average pregnancy lasts 40 weeks, give or take a few weeks depending on the circumstances. One trimester lasts 12 weeks, which means there are three trimesters in a pregnancy.
http://www.babycenter.com/400_when-does-the-third-trimester-begin_3275801_268.bc http://www.medicinenet.com/stages_of_pregnancy_pictures_slideshow/article.htm http://www.babycenter.com/400_when-does-the-3rd-trimester-start_945249_31.bc http://wanttoknowit.com/when-does-your-third-trimester-start/ http://www.thelaboroflove.com/articles/when-does-the-second-trimester-begin http://www.thebump.com/t/third-trimester http://www.ehow.com/info_12290395_third-trimester-begin.html
when does pregnancy third trimester start