Weeks and Trimesters These Moms Tell You What to Expect in Your First Trimester Share Pin Email More in Weeks and Trimesters Your Pregnancy Week by Week Updated May 27, 2016 So, here's the thing. Your first trimester is—as one mom states—no joke. The good news? It doesn't last forever. These moms talk candidly about their first trimesters, leaving no details behind.