Hospital-grade breast pumps are the most powerful, designed for frequent, heavy-duty use, particularly beneficial for mothers of premature infants or those with lactation challenges.

Many modern breast pumps incorporate adjustable suction levels and cycling speeds to mimic a baby's natural feeding patterns, aiming to optimize comfort and milk production for the user.

[9] In 1956 Einar Egnell published his groundbreaking work, "Viewpoints on what happens mechanically in the female breast during various methods of milk collection".

This use of breast milk is widespread in the United States, where paid family leave is one of the shortest in the developed world.

American historian Jill Lepore argues that the need for so-called "lactation rooms" and breast pumps is driven by the corporate desire for parents to return to work immediately rather than mothers' wishes or babies' needs.

[13][14] In a 2012 policy statement, the American Academy of Pediatrics recommended feeding preterm infants human milk, finding "significant short- and long-term beneficial effects," including lower rates of necrotizing enterocolitis (NEC).

[18] Research done at Stanford University in 2009 showed the correlation of various factors with the volume of milk production in mothers of preterm babies (born before the 31st week of gestation).

[20] A second article on the same study found that the combination of HOP techniques increased the fat content of the milk expressed.

[21] Manual breast pumps are operated by squeezing or pulling a handle in a repetitive fashion, allowing the user to directly control the pressure and frequency of milk expression.

Though manual pumps are small and inexpensive, they can require significant effort and can be tiring because the user provides all the power.

"Bicycle-horn" style manual pumps can damage breast tissue and harbor bacteria in the rubber suction bulb, which is difficult to clean.

Electric breast pumps are powered by a motor which supplies suction through plastic tubing to a horn that fits over the nipple.

Some electric pumps allow multi-user operation but recommend an accessory kit for each user to maintain cleanliness.

Freezable breastmilk storage bags are available that connect directly to some breast pumps and can then be used with disposable bottle feeding systems.

Egnell in 1956 established a 220 mmHg safe maximum for automatic cycling pumps; however, there have been reports of sensitive breasts and nipples at much lower pressures.

In this design, the suction of the pump motor lifts the diaphragm to create a vacuum within the collection system to extract milk.

These pumps have added hygienic benefit in that all the parts that generate the suction and come in contact with breast milk stay with the mother.

Some manufacturers offer adapters to fit a variety of types and sizes of bottles, enabling more flexibility to mix and match products of different brands.