At 33 weeks of pregnancy, it is normal for your baby to have regular periods of activity and rest. While there is no set duration for how long your baby should be moving inside your stomach, you should feel at least 10 movements within a two-hour period. These movements can vary in intensity and frequency throughout the day. If you notice a decrease in your baby's movement or if you are concerned about their activity level, it is important to contact your healthcare provider. They can provide guidance and perform any necessary tests to ensure the well-being of both you and your baby.