A: Congratulations on continuing to feed your baby breast milk, in spite of the challenges you've experienced. Exclusively pumping is no easy task! How much your baby needs to eat each day depends on many factors, including her age and weight and the nutrient composition of your breast milk, so there's no one-size-fits-all answer. During your baby's second month of life, she'll probably be feeding at least every three to four hours throughout the day and night. Most babies get enough to eat after about 15 to 20 minutes of nursing or bottle-feeding, and it's never a good idea to push your baby to finish all of the milk in the bottle if she doesn't seem to want it, no matter how hard you worked to produce it! On the other hand, if your baby still seems hungry, it's perfectly acceptable to offer her more. Healthy babies are very good at regulating their nutrient intake based on their needs.
Growth spurts can occur at different ages for different babies, but during the first few weeks of life, your baby will need increasing amounts of breast milk to support her rapid growth and increased hunger. The best way to determine if she's getting enough to eat is to have your pediatrician check her weight gain and growth regularly and carefully. If she's growing and gaining weight normally, based on her birth weight and current age, she's definitely getting enough to eat.
Exclusively pumping has a unique set of challenges for moms. Because you're using a bottle, you have the benefit of measuring exactly how much milk your baby is consuming at each feeding. If your baby were nursing directly from your breast, on the other hand, you'd have a hard time knowing exactly how many ounces she consumed at each feeding. Because you're using a bottle, you might be more concerned when your baby doesn't finish the entire bottle at any given feeding.
While foremilk from the breast is somewhat watery, hind-milk is nutrient and calorie dense. A baby must nurse longer or more aggressively from the breast to get the hind-milk at each feeding. This is nature's way of preventing over-feeding. Because you're pumping your milk and putting it into baby bottles, the foremilk and hind-milk get mixed together, so that your breast milk takes on a more consistent nutrient mix, in the same way that infant formula is a consistent nutrient mix. For moms who exclusively pump, there's probably no sure-fire way to exactly duplicate the amount of foremilk and hind-milk your baby would get if she were nursing directly from the breast. Some moms feed their pumped breast milk to their babies at roughly the same time of day that it was pumped to more closely match the nutrient demands dictated by the baby's circadian rhythms. For example, if you pump your milk at 2:00 in the afternoon, you might store that milk in a container labeled with the date and "2:00 pm." Later in the week, when your baby is hungry and ready to eat around 2:00 pm, you would offer her that milk, rather than the milk you collected at 5:00 am. That's a lot of extra work, and it's certainly not necessary for your baby's proper growth and development.
If you have any concerns at all about the way that your daughter is feeding or the amount of breast milk that she's consuming, don't hesitate to ask your pediatrician. As long she's continuing to grow and gain weight at an appropriate rate, you can relax and enjoy your beautiful baby girl.