The effects of breastfeeding on cognitive and neurological development of children at 9 years

Background The effect of breastfeeding on cognitive development in the child remains controversial. The commonly observed association between breastfeeding and higher intelligence quotient (IQ) scores in children may result from the numerous confounding factors in this complex relationship. The aim of this study was to examine whether breastfeeding is associated with later differences in children's cognitive and neurological development. Methods Secondary analysis from a 9‐year follow‐up study of children of 982 smokers recruited to a randomized controlled trial of anti‐smoking education in pregnancy in a maternity hospital between November 1981 and October 1982; and all ex‐smokers and a random 25% sample of non‐smokers during the same period (total 1853 women). Cognitive and neurological development of children was assessed by psychologists in schools using the British Ability Scales and Quick Neurological Screening Test (QNST). Data on breastfeeding and factors relevant to child development were drawn from interviews with mothers at home. Main outcome measures were IQ and QNST scores. Results A total of 1218 (66%) children were followed up. In total, 61.6% of children were breastfed, median duration being 12 weeks. Before adjustment, breastfeeding was significantly associated with higher total, verbal and visual IQ scores in children, and increasing duration was significantly correlated with IQ scores. Total IQ was 5.49 points higher in breastfed children (P≤ 0.001), but became non‐significant after adjustment. Total IQ scores were most strongly associated with maternal education, maternal age, parity, housing and chronic childhood illness. Breastfeeding was significantly associated with better QNST scores on bivariate analysis but not after adjustment. QNST scores were most strongly associated with maternal education and the child's sex. Conclusions Breastfeeding was not associated with any crude IQ advantage or difference in neurological soft signs in children at 9 years. The greater IQ score associated with breastfeeding is accounted for by confounding, with maternal and socio‐economic characteristics particularly important.     

学龄前儿童血红蛋白浓度与智力发育水平的相关性研究

目的 探讨学龄前儿童血红蛋白(Hb)浓度与智力发育水平之间的相关性.方法 研究对象为河北、江苏、浙江3省21个市县1993-1996年出生的7331名儿童.平均54月龄时测量Hb浓度;平均68月龄时使用中国-韦氏幼儿智力量表进行智力测试.分析Hb浓度与全量表智商、语言智商和操作智商得分之间的关系.结果 贫血组与非贫血组儿童的语言智商得分分别为91.6±18.0、92.3±17.5(P=0.144),操作智商得分分别为102.2±15.6、103.1±15.0(P=0.055),全量表智商得分分别为96.4±17.1、97.3±16.4(P=0.079).调整儿童性别、智力测量时月龄、地区、产次以及母亲智商、文化程度、职业等因素之后,贫血组儿童发生低语言智商、操作智商、全量表智商得分的风险是非贫血儿童的1.3倍(OR=1.3,95%CI:1.1～1.6)、1.3倍(OR=1.3,95%CI:1.1～1.5)和1.4倍(OR=1.4,95%CI:1.2～1.6).按照每20个百分位间隔将lib浓度分成5组分析,Hb浓度偏低组(Hb＜110 g/l)、中等浓度组(117 g/L≤Hb＜122 g/L)、偏高组(Hb≥130 g/L)儿童的语言智商得分分别为90.6±18.1、94.0±17.6、91.0±16.4;操作智商得分分别为102.2±15.7、104.6±14.8、100.5±14.9,全量表智商得分分别为95.9±17.3、99.0±16.4、95.2±15.6;Hb浓度偏低或偏高组儿童的智力得分均低于Hb水平中等组,差异有统计学意义(P＜0.001).调整混杂因素后,Hb浓度偏低组儿童发生语言智商、操作智商、全量表智商得分较低的风险是Hb浓度中等浓度组儿童的1.4倍(OR=1.4,95%CI:1.1～1.7)、1.4倍(OR=1.4,95%CI:1.1～1.8)和1.5倍(OR=1.5,95%CI:1.2～1.8).未见Hb浓度偏高组儿童发生低智商得分的风险高于Hb水平中等组.结论 儿童低Hb浓度可能对智力发育有不利影响.     

In utero exposure to background levels of polychlorinated biphenyls and cognitive functioning among school-age children

Polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants. In utero exposure to background levels of PCBs has been associated with intellectual impairment among children in most, but not all, studies. The authors evaluated prenatal PCB exposure in relation to cognitive test (intelligence quotient (IQ)) scores on the Wechsler Intelligence Scale for Children at age 7 years. Pregnant women were recruited from 12 US study centers from 1959 to 1965, and their children were followed until age 7 years (the Collaborative Perinatal Project). Third trimester serum was analyzed for PCBs in 1997-1999 for 732 women selected at random and for an additional 162 women whose children had either a low or a high IQ score. The PCB-IQ association was examined in multivariate models. Among those in the lowest exposure category (<1.25 microg of PCB/liter of serum), the fully adjusted mean IQ score was 93.6 (standard error: 1.8); among those in the highest category (> or =5 microg of PCB/liter), the mean IQ was 97.6 (standard error: 1.2); and overall the increase in IQ per unit increase in PCB level (microg/liter) was 0.22 (95% confidence interval: -0.28, 0.71). In these data, in utero exposure to background levels of PCBs was not associated with lower IQ at age 7 years.     

The effect of breastfeeding on children's educational test scores at nine years of age: results of an Irish cohort study

This retrospective cross-sectional paper examines the relationship between early breastfeeding exposure and children's academic test scores at nine years of age independent of a wide range of possible confounders. The final sample comprised 8226 nine-year-old school children participating in the first wave of the Growing Up in Ireland study. The children were selected through the Irish national school system using a 2-stage sampling method and were representative of the nine-year population. Information relating to breastfeeding initiation and exposure duration was obtained retrospectively at nine years of age via parental recall and children's academic performance was assessed using standardised reading and mathematics tests. Hierarchical linear regression analysis with robust standard errors to control for clustering at the school level was used to quantify the effect of breastfeeding on children's test scores. Propensity score matching was used to compare treatment effects across groups defined by their propensity to breastfeed. In unadjusted analysis, children who were breastfed scored 8.67 percentage points higher on reading and 7.42 percentage points higher on mathematics compared to those who were never breastfed. While the breastfeeding advantage attenuated appreciably when adjusted for a range of child, maternal, socio-economic and socio-environmental characteristics, children who were breastfed continued to enjoy a significant test score advantage of 3.24 (p<0.001) and 2.23 (p<0.001) percentage points on reading and mathematics respectively compared to those who were never breastfed. Any amount of breastfeeding was associated with significantly higher test scores than no exposure, but evidence of a dose-response relationship was weak. The results of the propensity score matching analysis indicated that the test score advantage of breastfed children is robust and that the magnitude of the effect varies across groups defined by their propensity to breastfeed, being largest amongst the most socially disadvantaged and falling to near zero among the most advantaged group.     

Does breastfeeding at six months predict cognitive development?

There is controversy over whether the method of feeding in infancy affects intellectual development. We investigated the relationship between breastfeeding status at 6 months of age and long-term cognitive development in a cohort of 375 children born in Port Pirie, South Australia, between 1979 and 1982. Cognitive assessments were conducted at ages 2, 4, 7 and 11 to 13 years. After adjustment for sociodemographic, environmental and biomedical factors, a small, statistically non-significant, beneficial effect of breastfeeding on cognitive functioning was observed. Compared with the bottle-fed children, the breast-fed children had a 3.4 (95% C1 -0.1 to 6.9), 1.3 (-2.3 to 4.9), 1.2 (-2.0 to 4.4) and 0.8 (-1.9 to 3.5) point advantage on the Bayley Mental Developmental Index at age 2 years, the McCarthy General Cognitive Index at age 4 years and the Wechsler Full-Scale IQ at ages 7 and 11 to 13 years, respectively. Our data suggest that any beneficial effect of breastfeeding on cognitive development is quite small in magnitude.     

低危晚期早产儿学龄前期认知和视觉运动整和能力研究

【目的】 探究学龄前期低危晚期早产儿认知发育状态和视觉-运动整合能力,比较其与同龄正常儿童的差异,为实施针对性干预方案提供依据。 【方法】 以上海-Wechsler学前及初学儿童智能测验量表和中国修订Beery视觉-运动整合测验工具评估69例学龄前期儿童(其中早产儿31例,正常足月儿38例)的智能和视觉运动整合能力。 【结果】 早产儿组的语言、操作和总智能分均值为:97±21、107±15、102±18;正常足月儿组依次为112±15、128±12、122±11。两组儿童智能虽处于平均水平,但早产儿组的认知能力远低于正常足月儿组(t=5.53,P<0.01),尤其在高级语言能力和操作能区上表现的更为薄弱。早产儿和正常足月儿组的视觉-运动整合能力均值分别为:88±16、109±18,两组间差异有高度统计学意义(t=4.93,P<0.01),且其差距较操作能区的差异还要大,达到了24%。将视觉-运动整合分值与总智商做相关分析发现,两者存在着正相关(r=0.6,P<0.05)。 【结论】 低危晚期学龄前期早产儿,虽具备正常认知能力,但仍较正常足月儿落后,尤其在高级语言功能和视觉感知运动方面,差距甚大。应在学龄前期对这类儿童加强随访评估,实施针对性干预措施。     

母亲孕早期血红蛋白水平与学龄前儿童智力发育的关系

目的 探讨母亲孕早期血红蛋白(Hb)水平对学龄前儿童智力发育的影响.方法 研究对象为浙江、江苏省13市(县)在1993-1996年期间分娩的妇女,2000-2001年对这些妇女所生育的儿童(平均68月龄)随机抽样,共得到3609个母子对.使用中国-韦氏幼儿智力量表对儿童进行智力测试;母亲孕早期的Hb浓度在首次产前检查时获得.分析母亲孕早期Hb浓度与所生儿童全量表智商、语言智商和操作智商得分之间的关系.结果 孕早期贫血组妇女所生儿童的语言智商、操作智商以及全量表智商得分,比非贫血组妇女所生儿童的智商得分分别高0.6、0.9和0.8分.调整儿童性别、智力测量时月龄、地区、产次以及母亲智商、文化程度、职业等因素后,未发现母亲孕早期贫血与儿童低语言智商、操作智商和全量表智商的风险之间存在统计学联系.按照每20个百分位间隔将妊娠期妇女孕早期Hb分成5组分析,Hb浓度偏低组(Hb＜103 g/L)、中等组(110 g/L≤Hb＜116 g/L)、偏高组(Hb≥124g/L)妇女所生儿童的语言智商得分分别为91.6±18.9、92.8±18.2、90.3±18.6;操作智商得分分别为104.7±15.2、104.5±14.3、103.5±15.1,全量表智商得分分别为97.8±17.3、98.4±16.3、96.4±17.4.调整混杂因素后,孕早期Hb偏高组妇女所生儿童低语言智商及低全量表智商得分的风险分别比孕早期Hb中等浓度组妇女所生儿童高54%(OR=1.54,95%CI:1.13～2.11)和53%(OR=1.53,95%CI:1.10～2.12),但未发现与儿童低操作智商得分风险存在统计学关联.母亲孕早期低Hb水平与儿童低语言、操作或全量表智商风险之间不存在统计学联系.结论 母亲孕早期过高的Hb浓度可能对其所生子女的语言智商有不利影响.     

学龄前儿童智力水平和智力结构

目的:调查幼儿园大班全部儿童的智力水平,分析其智力结构,探讨认知能力发育规律,为学龄前儿童的学校教育和健康成长提供参考依据。方法:选择金坛市3家幼儿园大班全体儿童作为调查对象,共计345名儿童(男191人,女154人)参加此次调查,采用中国版韦克斯勒氏学龄前及初小儿童智力量表(WPPSI)一对一测定儿童智力。结果:所有儿童的平均智商为(101.80±11.88)。总智商在不同性别间无差异(P>0.05),男、女童的言语智商均小于操作智商(P<0.01)。有28.70%的儿童发生智商分离,其中,言语智商小于操作智商的占69.70%,智商分离与智商平衡者之间总智商的差异无统计学意义(P>0.05)。智力离散模型分析并无明显趋势,但言语分量表的离散值小于操作分量表的离散值(P=0.000)。结论:本组学龄前儿童言语智商小于操作智商,可能是:①儿童更多地接触相关材料选择性地提高了操作能力;②中国80年代修订的WPPSI需要修改以符合时代的发展;③儿童智力的离散模型值得进一步追踪研究。     

Maternal recall of breastfeeding duration by elderly women

Studies of long-term effects of breastfeeding on the health of both infants and mothers often rely on maternal recall of breastfeeding duration after several decades. The authors evaluated this recall by 140 college-educated, US women 69-79 years of age who breastfed a child in 1940-1956 and recorded the duration both prospectively in a diary for the Menstruation and Reproductive History Study and retrospectively in a questionnaire in 1990-1991. Mean prospective breastfeeding duration was 5.6 months (range, 1-12 months). Mean reporting difference, questionnaire minus diary duration, was 0.0 months, with a standard deviation of 2.7 months; women who recorded short durations tended to overreport, while women who noted long durations underreported. The weighted kappa statistic for reporting agreement was 0.55 (95% confidence interval: 0.42, 0.67), with better recall observed for women in the youngest quintile at recall, firstborns, and infants with more siblings. Ever having breastfed was recalled by 94% of women. For categories of 1-3, 4-6, 7-9, and 10-12 months, recalled breastfeeding duration was correctly classified by 54% of women and was classified within +/-1 category by 89%. The observed misclassification, if nondifferential with respect to outcome, would appreciably attenuate estimates of dose-response associations between breastfeeding duration and later health.     

Intellectual and psychosocial functions of children, adolescents and young adults before and after operation for craniopharyngioma

Summary An evaluation of intellectual, personal and social functioning was made in 16 young patients with craniopharyngioma. No changes were found in the overall IQ verbal and performances scores before and after operation, however, discrepancies between verbal and performance scores suggest that one of the manifestations of craniopharyngioma in children are disturbances in cognitive functions. The decrease in the quality of life of the patients and their families manifested through the deterioration of familial and social relationships and the decrease in scholastic achievements lead to the conclusion that children with craniopharyngioma and their families require close psychological supervision and counselling both before and after surgery.     

Breastfeeding, weight gain in infancy, and overweight at seven years of age: the prevention and incidence of asthma and mite allergy birth cohort study

Compared with nonbreastfed children, breastfed children tend to have a lower body mass index (BMI) at about 1 year of age. How the BMI of breastfed children develops after the first year when this difference in BMI at 1 year of age is considered is not clear. The authors studied the association between breastfeeding and BMI development from 1 to 7 years of age independently of BMI at 1 year of age. Longitudinal BMI data reported by parents of 2,347 Dutch children born in 1996-1997 who participated in the Prevention and Incidence of Asthma and Mite Allergy birth cohort study were collected. Linear regression and mixed-effects models were used for data analyses. Mean BMI at 1 year of age was 17.2 kg/m(2) (standard deviation, 1.4). Compared with nonbreastfed children, children breastfed for >16 weeks had a lower BMI at 1 year of age, after adjustment for confounders (beta = -0.22, 95% confidence interval: -0.39, -0.06). The association between breastfeeding and BMI between 1 and 7 years of age was negligible, while a high BMI at 1 year of age was strongly associated with a high BMI between 1 and 7 years of age in the same model. These findings suggest that the lower BMI and lower risk of overweight among breastfed children later in life are already achieved at 1 year of age.     

Einflussfaktoren auf Verbreitung und Dauer des Stillens in Deutschland

Breastfeeding is the natural way of feeding infants in the first months of their lives and has been proven to have health benefits for both infants and mothers. Breastfeeding initiation and duration are affected by social, demographic and health factors. The aim of this study was to describe the current rates of breastfeeding initiation and duration in Germany, and to identify potential factors that underline these rates. Additionally, results are compared with the KiGGS basic (2003–2006; birth cohorts 1996–2002) study in order to reveal the development in the trends of breastfeeding initiation and duration in Germany. The KiGGS wave 1 (2009–2012) includes data on the breastfeeding behavior of mothers of 4410 children aged between 0 and 6 years (birth cohorts 2002–2012). Altogether, 82?% (95?% confidence interval 79.8–84.2 %) of children were ever breastfed, and the average breastfeeding duration was 7.5 months (7.2–7.8). There was a slight increase in the breastfeeding initiation in Germany over the last several years. Breastfeeding initiation among children aged 0-6 years increased by 4?% points compared to 0- to 6-year-olds (birth cohorts 1996–2002) from the KiGGS basic study. The breastfeeding duration stayed unchanged. The breastfeeding behavior was mainly related to the age of the mother at birth, the mother’s education level, smoking during pregnancy, and multiple or premature birth. Despite the overall increasing trend in breastfeeding initiation, there is still a growing need for breastfeeding promotion and support for young and less educated mothers, mothers who smoke during pregnancy, and also for mothers with premature babies or multiple births.     

Infant feeding patterns and risks of death and hospitalization in the first half of infancy: multicentre cohort study

OBJECTIVE: To determine the association of different feeding patterns for infants (exclusive breastfeeding, predominant breastfeeding, partial breastfeeding and no breastfeeding) with mortality and hospital admissions during the first half of infancy. METHODS: This paper is based on a secondary analysis of data from a multicentre randomized controlled trial on immunization-linked vitamin A supplementation. Altogether, 9424 infants and their mothers (2919 in Ghana, 4000 in India and 2505 in Peru) were enrolled when infants were 18-42 days old in two urban slums in New Delhi, India, a periurban shanty town in Lima, Peru, and 37 villages in the Kintampo district of Ghana. Mother-infant pairs were visited at home every 4 weeks from the time the infant received the first dose of oral polio vaccine and diphtheria-pertussis-tetanus at the age of 6 weeks in Ghana and India and at the age of 10 weeks in Peru. At each visit, mothers were queried about what they had offered their infant to eat or drink during the past week. Information was also collected on hospital admissions and deaths occurring between the ages of 6 weeks and 6 months. The main outcome measures were all-cause mortality, diarrhoea-specific mortality, mortality caused by acute lower respiratory infections, and hospital admissions. FINDINGS: There was no significant difference in the risk of death between children who were exclusively breastfed and those who were predominantly breastfed (adjusted hazard ratio (HR) = 1.46; 95% confidence interval (CI) = 0.75-2.86). Non-breastfed infants had a higher risk of dying when compared with those who had been predominantly breastfed (HR = 10.5; 95% CI = 5.0-22.0; P < 0.001) as did partially breastfed infants (HR = 2.46; 95% CI = 1.44-4.18; P = 0.001). CONCLUSION: There are two major implications of these findings. First, the extremely high risks of infant mortality associated with not being breastfed need to be taken into account when informing HIV-infected mothers about options for feeding their infants. Second, our finding that the risks of death are similar for infants who are predominantly breastfed and those who are exclusively breastfed suggests that in settings where rates of predominant breastfeeding are already high, promotion efforts should focus on sustaining these high rates rather than on attempting to achieve a shift from predominant breastfeeding to exclusive breastfeeding.     

Breastfeeding and cognitive development in the first 2 years of life

The relationship between breastfeeding and cognitive development in the first 2 years of life was examined in a cohort of children being followed in a study of risk factors in development. A significant difference between bottlefed children, children breastfed less than or equal to 4 months and those breastfed greater than 4 months was found on the Mental Development Index of the Bayley Scales at ages 1 and 2 years, favoring the breastfed children. At age 6 months, the direction of the relationship was the same but did not reach significance. Supplementary regression analyses examining the strength of the relationship between duration of breastfeeding and cognitive development similarly showed a small but significant relationship between duration of breastfeeding and scores on the Bayley at 1 and 2 years. Alternative explanations for the results are discussed.     

Being breastfed in infancy and breast cancer incidence in adult life: results from the two nurses' health studies

Events during perinatal and early life may influence the incidence of breast cancer in adult life, and some case-control studies suggest that having been breastfed may reduce breast cancer risk. The authors studied this association among premenopausal and postmenopausal women by using data from the two Nurses' Health Studies, the Nurses' Health Study (using data from 1992 to 1996) and the Nurses' Health Study II (using data from 1991 to 1997). A history of being breastfed was self-reported by the study participants. During a total of 695,655 person-years, 1,073 cases of invasive breast cancer were diagnosed. The authors did not observe any important overall association between having been breastfed and the development of breast cancer later in life among premenopausal women (covariate-adjusted relative risk = 0.97, 95% confidence interval (CI): 0.78, 1.20) or postmenopausal women (covariate-adjusted relative risk = 1.12, 95% CI: 0.92, 1.37). No significant trend was observed with increasing duration of breastfeeding. The authors also used data on breastfeeding retrospectively collected from 2,103 mothers of participants of the two Nurses' Health Studies. With the mothers' reports, the covariate-adjusted odds ratio of breast cancer was 1.11 (95% CI: 0.88, 1.39) for women who were breastfed compared with those who were not. Data from these two large cohorts do not support the hypothesis that being breastfed confers protection against subsequent breast cancer.     

Preventive education and birth order as co-determinants of IQ in disadvantaged 5-year-olds

The effects of preventive education and birth order on IQ scores of 95 economically disadvantaged children at risk for retarded intellectual development were studied. Experimental first- and later-born children participated from birth in a 5-year programme of systematic educational intervention. An equal number of children served as controls and received no systematic intervention. First-borns prevailed as the brighter children in both the educational treatment group and the control group when Wechsler Preschool and Primary Scale of Intelligence (WPPSI) full scale and verbal IQ scores were compared. Furthermore, mothers of first-borns (70% of whom were only-born at age 5) achieved significantly higher WAIS scores than did mothers of later-born children. Results suggest that later-born disadvantaged children are at greatest risk for developmental retardation.     

Low-level environmental lead exposure and children's intellectual function: an international pooled analysis

Lead is a confirmed neurotoxin, but questions remain about lead-associated intellectual deficits at blood lead levels < 10 microg/dL and whether lower exposures are, for a given change in exposure, associated with greater deficits. The objective of this study was to examine the association of intelligence test scores and blood lead concentration, especially for children who had maximal measured blood lead levels < 10 microg/dL. We examined data collected from 1,333 children who participated in seven international population-based longitudinal cohort studies, followed from birth or infancy until 5-10 years of age. The full-scale IQ score was the primary outcome measure. The geometric mean blood lead concentration of the children peaked at 17.8 microg/dL and declined to 9.4 microg/dL by 5-7 years of age; 244 (18%) children had a maximal blood lead concentration < 10 microg/dL, and 103 (8%) had a maximal blood lead concentration < 7.5 microg/dL. After adjustment for covariates, we found an inverse relationship between blood lead concentration and IQ score. Using a log-linear model, we found a 6.9 IQ point decrement [95% confidence interval (CI), 4.2-9.4] associated with an increase in concurrent blood lead levels from 2.4 to 30 microg/dL. The estimated IQ point decrements associated with an increase in blood lead from 2.4 to 10 microg/dL, 10 to 20 microg/dL, and 20 to 30 microg/dL were 3.9 (95% CI, 2.4-5.3), 1.9 (95% CI, 1.2-2.6), and 1.1 (95% CI, 0.7-1.5), respectively. For a given increase in blood lead, the lead-associated intellectual decrement for children with a maximal blood lead level < 7.5 microg/dL was significantly greater than that observed for those with a maximal blood lead level > or = 7.5 microg/dL (p = 0.015). We conclude that environmental lead exposure in children who have maximal blood lead levels < 7.5 microg/dL is associated with intellectual deficits.     

Relation of blood pressure to cognitive function in the elderly.

Clinical case-control studies of the relation between blood pressure and cognitive function have generally found lower function among hypertensives. Most of these studies were small and incompletely controlled for confounders. Two population-based studies have yielded conflicting results. This study examines cognitive function over the entire range of blood pressure in a defined elderly population. A questionnaire administered in the home to 3,809 persons aged greater than or equal to 65 years in East Boston, Massachusetts, in 1982 and 1983 contained four brief cognitive tests: immediate memory, delayed memory, a mental status questionnaire, and digit span. In linear regression analyses adjusting for age, sex, and education, the direction of the association was not consistent among the tests. An increase in diastolic pressure of 10 mmHg was associated with an increase of 1.0 in percentile scores on the immediate memory test (95% confidence interval (CI) -0.04 to 1.9); with an increase of 1.1 in percentile scores on the delayed memory test (95% CI -0.1 to 2.3); with a decrease of -0.8 in percentile scores on the mental status questionnaire (95% CI -1.8 to 0.2); and with a decrease of -0.9 in percentile scores on the attention test (95% CI -1.5 to -0.2). These results suggest that blood pressure is not a substantial contributor to cognitive status in the elderly.