The third trimester of pregnancy begins at week 28 and continues until birth, which typically occurs around week 40 (or a few weeks later).Nutrition & Wellness Tips for the Third Trimester. Preparing for Labor & Birth. When to Contact Your Healthcare Provider.
The third trimester, while exiting, often brings with it added aches and pains, less sleep, frequent attention from strangers (there's no hiding your pregnancy now!), and lots more prenatal appointments.
Pregnancy: Gestation, Trimesters & What To Expect - Cleveland Clinic.

The Three Stages of Pregnancy (1st, 2nd, and 3rd Trimester). Conception to about the 12th 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.
Understanding the Three Trimesters. Category: Women's Health, Pregnancy and Childbirth.Third Trimester - Weeks 29 through 40. At this stage in your pregnancy, your little one is reaching the end of fetal development, forming major organ systems and increasing in size rapidly.

Third trimester nausea is common and usually not serious.If feeling excessively nauseated during the third trimester is a new thing for you this pregnancy, you should check in with your doctor. Your stomach upset could still be caused by your changing body or an external factor like diet.