Simondon K B, Simondon F
Nutrition Unit, Institut Français de Recherche Scientifique pour le Développement en Coopération, Montpellier, France.
Int J Epidemiol. 1998 Jun;27(3):490-4. doi: 10.1093/ije/27.3.490.
Breastfeeding, when prolonged beyond infancy, is a risk factor for low nutritional status in most cross-sectional samples from less developed countries. Therefore, it has been suggested that prolonged breastfeeding impairs growth. To test whether, on the contrary, breastfeeding is prolonged because the child is already undernourished, nutritional status prior to weaning was compared according to age at weaning.
Precise dates of birth and weaning were collected weekly through continuous demographic surveillance in a rural area of Senegal. Weight and length at 9-10 months were measured during vaccination sessions (coverage: 78%) from 1989 to 1996. Eight infants weaned before 9 months were excluded, and the duration of breastfeeding of the remaining 4515 children was compared according to nutritional status at 9-10 months by survival analysis.
Length-for-age during infancy was associated with duration of breastfeeding: the median duration was 25.0 months for z-scores <-2, 24.1 months for z-scores -2 to -1, 23.4 months for z-scores -1 to 0 and 22.7 months for z-scores >0 (P for trend <0.0001). Weight-for-length during infancy was also associated with duration of breastfeeding (P for trend <0.0001), though the differences among groups were smaller. The relationships remained at the same significance levels after adjustment for season of birth, mother's age, parity, height, occupation and education.
Duration of breastfeeding is not determined by characteristics of the mothers only. Women prolong breastfeeding for undernourished children and reduce the duration for well-nourished children, probably because they are aware of the mortality risk following weaning.
在大多数来自欠发达国家的横断面样本中，母乳喂养若持续至婴儿期之后，是导致营养状况不佳的一个风险因素。因此，有人提出延长母乳喂养会损害生长发育。为了检验相反的情况，即母乳喂养延长是否是因为孩子已经营养不良，根据断奶时的年龄对断奶前的营养状况进行了比较。
通过在塞内加尔农村地区进行持续的人口监测，每周收集准确的出生日期和断奶日期。在1989年至1996年的疫苗接种期间（接种率：78%）测量了9至10个月大婴儿的体重和身长。排除了9个月前断奶的8名婴儿，并通过生存分析，根据9至10个月时的营养状况，对其余4515名儿童的母乳喂养持续时间进行了比较。
婴儿期的年龄别身长与母乳喂养持续时间相关：z评分＜-2时，中位持续时间为25.0个月；z评分为-2至-1时，为24.1个月；z评分为-1至0时，为23.4个月；z评分＞0时，为22.7个月（趋势P值＜0.0001）。婴儿期的身长别体重也与母乳喂养持续时间相关（趋势P值＜0.0001），尽管各组之间的差异较小。在对出生季节、母亲年龄、胎次、身高、职业和教育程度进行调整后，这些关系仍保持相同的显著水平。
母乳喂养持续时间并非仅由母亲的特征决定。母亲会延长对营养不良儿童的母乳喂养时间，缩短对营养良好儿童的母乳喂养时间，这可能是因为她们意识到断奶后存在死亡风险。
