2007年8月6日星期一

Breast pump

A breast pump is a mechanical device (powered manually or by electricity) that extracts milk from the breasts of a woman who is lactating. The breast pump was invented and patented by Edward Lasker. Mechanically, a breast pump is directly analogous to a milking machine used in commercial dairy production. A misconception is that the breast pump suctions milk out of the breast. A breast pump's job is to trigger the milk-ejection response or let-down. Most pumps achieve this goal by using suction to pull the nipple into the tunnel of the breast shield or flange then release, which counts as one cycle. Thirty to sixty cycles per minute can be expected with better quality electric breast pumps. It is important to note that in most cases the breast pump is not as efficient at removing milk from the breast as the nursing baby.
The expressed breast milk (EBM) may be stored and later fed to a baby by bottle. Expressed milk may be kept at room temperature for up to ten hours (at 66-72 degrees Fahrenheit, around 20 degrees Celsius), refrigerated for up to 8 days, or frozen for six months in a deep freeze separate from a refrigerator maintained at a temperature of 0 degrees Fahrenheit, −18 degrees Celsius. Expressed milk may be donated to milk banks, which provide human breast milk to premature infants and other high-risk children whose mothers cannot provide for them.
Electric breast pumpWomen use breast pumps for many reasons. Many women use breast pumps to continue breastfeeding after they return to work. They use the pump to express breast milk which is later bottle fed to their child by a caregiver. A breast pump may also be used to stimulate lactation for women with a low milk supply, or who have not just given birth. A breast pump may be used to relieve engorgement, a painful condition whereby the breasts are overfull, possibly preventing a proper latch by the infant. If an infant does not latch properly for direct breastfeeding, and the mother still desires the benefits of breast milk, she may choose to pump exclusively. If the mother needs to take medication that affects the breast milk and may be harmful to the infant, the mother may "pump and dump" the breast milk to keep up her milk supply during the time period that she is on the medication and may resume nursing after the course of medication is completed. Finally, pumping may be desirable to continue lactation and its associated hormones to aid in recovery from pregnancy even if the pumped milk is not used.

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