Manual units can be tiring to use, though, and may not be be effective enough for those who need it several times per day. Manual pumps are reliable, though, since there are fewer parts to break.
Battery-powered breast pumps are available, but they're not as popular as manual and electric pumps, and are not often recommended by lactation consultants or doctors. Battery pumps tend to cycle slower than a baby's sucking pattern and less powerful overall. A weaker unit can cause a drop in milk supply if used daily for expressing milk. Battery units are easily portable, but they require frequent battery replacements.
Electric units are the choice for mothers returning to work full-time or pumping exclusively. These pumps usually express milk from both breasts at once and most closely imitate a baby's sucking pattern, which helps maintain milk supply. Popular accessories include car AC adapters, built-in milk coolers, travel cases and hands-free kits. The downside to electric units is price. Expect to spend $200-$300 to buy a good electric breast