One size does not always fit all, we are all unique so Medela has PersonalFit™ breast shields in a range of sizes to meet every mom’s needs. Lactation professionals agree that proper breast shield fit is essential for not only comfort, but also for effective milk expression.The right breast shield size and a proper fit avoid compression of any milk ducts during pumping. As a consequence the mother is given the best chance of protecting of her milk volume, optimising breast emptying, preventing nipple trauma and pumping with comfort. This will help a mother to maintain her milk production and support her lactation. Using a too small or too large breast shield may lead to impaired milk removal because milk ducts could get blocked or milk ejection inhibited