Morning sickness typically starts around 6 weeks into pregnancy, which is about two weeks after the first missed period. Some women may begin to feel nauseous as early as week 4 to 5, but the most common onset is around week 6. It usually peaks between weeks 8 and 11 and tends to fade by the end of the first trimester, around 12 to 14 weeks, though some may experience it longer. Despite its name, morning sickness can occur at any time of the day and its severity varies widely among individuals. Not all pregnant women experience morning sickness, as about 30% may have no nausea at all.