The normal hormone levels associated with a healthy pregnancy do result in a lowered milk supply for women who are still breastfeeding. While working to maintain or increase your milk supply during this time is rarely successful, your toddler can still continue to nurse during this time. He will still get substantial immune and nutritional benefits from the milk that is there. But knowing that your supply will be naturally lower, you may need to add in some formula supplement or additional solids to meet your toddler’s nutritional needs during this time. Keep it up, and once the new baby is born, your milk supply will increase, and you will be able to provide more milk for your nursing toddler in addition to your new baby.