It is generally safe to breastfeed while pregnant, but there are some factors to consider. Breastfeeding during pregnancy can cause nipple tenderness and a decrease in milk supply, as your body prioritizes the needs of the growing fetus. However, if your pregnancy is healthy and you have no complications, continuing to breastfeed should not harm your older child. It's important to ensure that both you and your baby are getting proper nutrition during this time. If you experience any discomfort or concerns, consult with your healthcare provider for personalized advice.