Strøm Marin, Mortensen Erik Lykke, Kesmodel Ulrik Schiøler, Halldorsson Thorhallur, Olsen Jørn, Olsen Sjurdur F
Centre for Fetal Programming, Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark.
Faculty of Health Sciences, University of the Faroe Islands, Tórshavn, Faroe Islands.
BMJ Open. 2019 May 30;9(5):e023134. doi: 10.1136/bmjopen-2018-023134.
Breast feeding is associated with health benefits for both mother and child, but many studies focusing on neurodevelopment have lacked information on important confounders and few randomised trials exist. Our objective was to examine the influence of breast feeding on child IQ at 5 years of age while taking maternal IQ and other relevant factors into account.
Prospective observational study.
Population-based birth cohort in Denmark.
We used data from The Lifestyle During Pregnancy Study 1782 mother-child pairs sampled from the Danish National Birth Cohort (n=101 042).
Child IQ was assessed at age 5 years by the Wechsler Primary and Preschool Scales of Intelligence-Revised. On the same occasion maternal intelligence was assessed by Wechsler Adult Intelligence Scale and Raven's Standard Progressive Matrices. Exposure data on duration of breast feeding (n=1385) were extracted from telephone interviews conducted when the child was 6 and 18 months, and analyses were weighted by relevant sampling fractions.
In multivariable linear regression analyses adjusted for potential confounders breast feeding was associated with child IQ at 5 years (categorical χ test for overall association p=0.03). Compared with children who were breast fed ≤1 month, children breast fed for 2-3, 4-6, 7-9 and 10 or more months had 3.06 (95% CI 0.39 to 5.72), 2.03 (95% CI -0.38 to 4.44), 3.53 (95% CI 1.18 to 5.87) and 3.28 (95% CI 0.88 to 5.67) points higher IQ after adjustment for core confounders, respectively. There was no dose-response relation and further analyses indicated that the main difference in IQ was between breast feeding ≤1 month versus >1 month.
Breastfeeding duration of 1 month or shorter compared with longer periods was associated with approximately three points lower IQ, but there was no evidence of a dose-response relation in this prospective birth cohort, where we were able to adjust for some of the most critical confounders, including maternal intelligence.
母乳喂养对母亲和孩子都有健康益处，但许多关注神经发育的研究缺乏关于重要混杂因素的信息，且几乎没有随机试验。我们的目的是在考虑母亲智商和其他相关因素的情况下，研究母乳喂养对5岁儿童智商的影响。
前瞻性观察性研究。
丹麦基于人群的出生队列。
我们使用了来自孕期生活方式研究的数据，从丹麦国家出生队列（n = 101042）中抽取了1782对母婴。
儿童智商在5岁时通过韦氏儿童智力量表修订版进行评估。同时，母亲智力通过韦氏成人智力量表和瑞文标准渐进矩阵进行评估。母乳喂养持续时间（n = 1385）的暴露数据从孩子6个月和18个月时进行的电话访谈中提取，并通过相关抽样分数进行加权分析。
在针对潜在混杂因素进行调整的多变量线性回归分析中，母乳喂养与5岁儿童智商相关（总体关联的分类χ检验p = 0.03）。与母乳喂养≤1个月的儿童相比，母乳喂养2 - 3个月、4 - 6个月、7 - 9个月和10个月及以上的儿童在调整核心混杂因素后，智商分别高出3.06（95%CI 0.39至5.72）、2.03（95%CI -0.38至4.44）、3.53（95%CI 1.18至5.87）和3.28（95%CI 0.88至5.67）分。不存在剂量反应关系，进一步分析表明智商的主要差异在于母乳喂养≤1个月与>1个月之间。
与更长时间相比，母乳喂养1个月或更短时间与智商低约三分相关，但在这个前瞻性出生队列中没有证据表明存在剂量反应关系，在此队列中我们能够对一些最关键的混杂因素进行调整，包括母亲智力。
