When does morning sickness occur in pregnancy?: Morning sickness tends to be the first pregnancy symptom most women experience. It can start nearly as soon as the pregnancy test is positive, though many women will not notice morning sickness until about the sixth week of pregnancy.
Is it only in the morning?: You may experience morning sickness at any time of the day or night, though most women do experience some uneasiness of the stomach early in the morning, probably because their stomachs are empty. If you are unlucky enough to suffer from this pregnancy symptom at work, there are things you can do to try to ease the symptoms and deal with it.

Morning Sickness - An Infamous Pregnancy Symptom