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Breastfeeding or nursing is feeding of babies and young children with milk from a woman's breast.〔(【引用サイトリンク】url=https://www.nichd.nih.gov/health/topics/breastfeeding/conditioninfo/Pages/default.aspx )〕 It is recommended to begin breastfeeding within the first hour of life and after that allow it as the baby wishes.〔 During the first few weeks of life babies may nurse eight to twelve times a day (every two to three hours). The duration of a feeding is usually ten to fifteen minutes on each breast.〔(【引用サイトリンク】url=https://www.nichd.nih.gov/health/topics/breastfeeding/conditioninfo/Pages/how-is-it-done.aspx )〕 The frequency of feeding decreases as the child gets older.〔(【引用サイトリンク】url=https://www.nichd.nih.gov/health/topics/breastfeeding/conditioninfo/Pages/weaning.aspx )〕 Some mothers pump milk so that it can be used later when their child is being cared for by others.〔 Breastfeeding benefits both mother and baby.〔 Infant formula does not have many of the benefits.〔 It is estimated that greater than a million babies could be saved globally per year through greater breastfeeding. Breastfeeding decreases the risk of respiratory tract infections and diarrhea.〔 This is true both in developing and developed countries.〔 Other benefits include a lower risk of asthma, food allergies, celiac disease, type 1 diabetes, and leukemia.〔 Breastfeeding may also improve cognitive development and decrease the risk of obesity in adulthood.〔 Some mothers may feel considerable pressure to breastfeed, but children who are not breastfed grow up normally – without significant harm to their future health. Benefits of breastfeeding for the mother include less blood loss following delivery, better uterus shrinkage, weight loss, and less postpartum depression. It also increases the time before menstruation and fertility returns, known as lactational amenorrhea. Long term benefits may include a decreased risk of breast cancer, cardiovascular disease, and rheumatoid arthritis.〔 Breastfeeding is less expensive for the family than infant formula.〔(【引用サイトリンク】url=https://www.nichd.nih.gov/health/topics/breastfeeding/conditioninfo/Pages/benefits.aspx )〕 Health groups, such as World Health Organization (WHO), support six months of just breastfeeding.〔 This means that no other foods or drinks other than vitamin D are typically given.〔(【引用サイトリンク】url=https://www.nichd.nih.gov/health/topics/breastfeeding/conditioninfo/Pages/recommendations.aspx )〕 Continued partial breastfeeding until at least a year of age is then recommended.〔 Globally about 38% of infants are just breastfeed during their first six months of life.〔 In the United States about 75% of women begin breastfeeding and about 43% breastfeed until six months.〔 Medical conditions that do not allow breastfeeding are uncommon. During breastfeeding, recreational drugs and certain medications are not recommended.〔(【引用サイトリンク】url=https://www.nichd.nih.gov/health/topics/breastfeeding/conditioninfo/Pages/when-not-breastfeed.aspx )〕 ==Lactation== (詳細はtrimesters), a woman's body produces hormones that stimulate the growth of the breast's milk duct system. Progesterone influences the growth in size of alveoli and lobes; high levels of progesterone, estrogen, prolactin and other hormones inhibit lactation before birth; hormone levels drop after birth, triggering milk production. After birth, the hormone oxytocin contracts the smooth muscle layer of cells surrounding the alveoli to squeeze milk into the duct system. Oxytocin is also necessary for the milk ejection reflex, or ''let-down'' to occur. Let down occurs in response to the baby's suckling, though it also may be a conditioned response, e.g. to the cry of the baby. Lactation can also be induced by a combination of physical and psychological stimulation, by drugs or by a combination of these methods. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「breastfeeding」の詳細全文を読む スポンサード リンク
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