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Oxytocin is a hormone released from the pituitary gland in the brain. During pregnancy, this hormone causes labor contractions to start. It also is released when a woman's breasts are stimulated by suckling or pumping, causing milk to move from the ducts and out the tiny holes in the nipple. This is called the let-down reflex. In the first few days after delivery, oxytocin also causes uterine contractions. They help shrink the uterus back to the size it was before pregnancy.

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Current as of: October 2, 2023

Author: Healthwise Staff
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The Health Encyclopedia contains general health information. Not all treatments or services described are covered benefits for Kaiser Permanente members or offered as services by Kaiser Permanente. For a list of covered benefits, please refer to your Evidence of Coverage or Summary Plan Description. For recommended treatments, please consult with your health care provider.