The short answer
Morning sickness typically begins around 5–6 weeks of pregnancy, often peaks around 9 weeks, and eases between 12 and 16 weeks. It affects about 80% of pregnant women and can occur at any time of day, not just mornings.
See morning sickness for tips, and when it becomes dangerous.
Answered by Dami Women's Clinic (다미산부인과의원), Yeouido, Seoul · Dr. Ko Sang-hyun, OB/GYN. General information, not a diagnosis. Emergencies in Korea: call 119. Medical disclaimer · International Patient Center