Marquis G S, Habicht J P, Lanata C F, Black R E, Rasmussen K M
Division of Nutritional Sciences, Cornell University, Ithaca, NY, USA.
Int J Epidemiol. 1997 Apr;26(2):349-56. doi: 10.1093/ije/26.2.349.
Child feeding recommendations include breastfeeding beyond 12 months, however, some researchers have reported increased rates of malnutrition in breastfed toddlers. A negative association between growth and breast-feeding may reflect reverse causality; that is, the outcome (growth) is a determinant of the predictor (breastfeeding), and not vice versa. We examined this question with data from 134 Peruvian toddlers.
A linear regression analysis predicted length at the age of 15 months by length at 12 months, study interval, and 12-14.9-month breastfeeding, complementary food intake, and diarrhoeal incidence. This analysis defined the association between breastfeeding and linear growth. To elucidate the direction of the effect between breastfeeding and linear growth, logistic regression was used to predict the probability of weaning by the end of 14 months. Determinants included weight-for-age (W/A) at 12 months, complementary food intake at 9-11.9 months, and change in diarrhoeal incidence between 9 and 14.9 months.
There was a significant (P < 0.01) interaction of breastfeeding, diarrhoeal incidence, and complementary food intake on length at 15 months. Increased breastfeeding was associated with a 1.0 cm decrease in length gain when dietary intake was low and diarrhoeal morbidity was high, implying that breastfeeding is harmful. The logistic analysis, however, demonstrated that the risk of weaning decreased only when W/A and dietary intake were low and diarrhoeal morbidity was high.
The negative association between breastfeeding and linear growth reflected reverse causality. Increased breastfeeding did not lead to poor growth; children's poor growth and health led to increased breastfeeding. Children's health must be considered when evaluating the association of breastfeeding with anthropometric outcomes.
儿童喂养建议包括母乳喂养至12个月以上，然而，一些研究人员报告称，母乳喂养的幼儿营养不良率有所上升。生长与母乳喂养之间的负相关可能反映了反向因果关系；也就是说，结果（生长）是预测因素（母乳喂养）的决定因素，而非反之。我们利用134名秘鲁幼儿的数据研究了这个问题。
线性回归分析通过12个月时的身长、研究间隔以及12至14.9个月的母乳喂养情况、辅食摄入量和腹泻发病率来预测15个月时的身长。该分析确定了母乳喂养与线性生长之间的关联。为了阐明母乳喂养与线性生长之间影响的方向，采用逻辑回归来预测14个月末断奶的概率。决定因素包括12个月时的年龄别体重（W/A）、9至11.9个月时的辅食摄入量以及9至14.9个月期间腹泻发病率的变化。
母乳喂养、腹泻发病率和辅食摄入量对15个月时的身长存在显著（P<0.01）交互作用。当饮食摄入量低且腹泻发病率高时，母乳喂养增加与身长增长减少1.0厘米相关，这意味着母乳喂养有害。然而，逻辑分析表明，只有当W/A和饮食摄入量低且腹泻发病率高时，断奶风险才会降低。
母乳喂养与线性生长之间的负相关反映了反向因果关系。母乳喂养增加并不会导致生长不良；儿童生长不良和健康状况不佳导致母乳喂养增加。在评估母乳喂养与人体测量结果的关联时，必须考虑儿童的健康状况。
