The long-term effects of breastfeeding on child and adolescent mental health: a pregnancy cohort study followed for 14 years

Long-term differences in language and cognitive function after childhood exposure to anesthesia

BACKGROUND

Over the past decade, the safety of anesthetic agents in children has been questioned after the discovery that immature animals exposed to anesthesia display apoptotic neurodegeneration and long-term cognitive deficiencies. We examined the association between exposure to anesthesia in children under age 3 and outcomes in language, cognitive function, motor skills, and behavior at age 10.

METHODS

We performed an analysis of the Western Australian Pregnancy Cohort (Raine) Study, which includes 2868 children born from 1989 to 1992. Of 2608 children assessed, 321 were exposed to anesthesia before age 3, and 2287 were unexposed.

RESULTS

On average, exposed children had lower scores than their unexposed peers in receptive and expressive language (Clinical Evaluation of Language Fundamentals: Receptive [CELF-R] and Expressive [CELF-E]) and cognition (Colored Progressive Matrices [CPM]). After adjustment for demographic characteristics, exposure to anesthesia was associated with increased risk of disability in language (CELF-R: adjusted risk ratio [aRR], 1.87; 95% confidence interval [CI], 1.20-2.93, CELF-E: aRR, 1.72; 95% CI, 1.12-2.64), and cognition (CPM: aRR, 1.69; 95% CI, 1.13-2.53). An increased aRR for disability in language and cognition persisted even with a single exposure to anesthesia (CELF-R aRR, 2.41; 95% CI, 1.40-4.17, and CPM aRR, 1.73; 95% CI, 1.04-2.88).

CONCLUSIONS

Our results indicate that the association between anesthesia and neuropsychological outcome may be confined to specific domains. Children in our cohort exposed to anesthesia before age 3 had a higher relative risk of language and abstract reasoning deficits at age 10 than unexposed children.

Developmental status of 1-year-old infants fed breast milk, cow's milk formula, or soy formula

BACKGROUND AND OBJECTIVE

Although soy formula has been reported to support normal development, concerns exist regarding potential adverse developmental effects of phytochemicals associated with soy protein. This study characterized developmental status (mental, motor, and language) of breastfed (BF), milk-based formula-fed (MF), or soy protein-based formula-fed (SF) infants during the first year of life.

METHODS

Healthy infants (N = 391) were assessed longitudinally at ages 3, 6, 9, and 12 months. Development was evaluated by using the Bayley Scales of Infant Development and the Preschool Language Scale-3. Mixed effects models were used while adjusting for socioeconomic status, mother's age and IQ, gestational age, gender, birth weight, head circumference, race, age, and diet history.

RESULTS

No differences were found between formula-fed infants (MF versus SF). BF infants scored slightly higher than formula-fed infants on the Mental Developmental Index (MDI) score at ages 6 and 12 months (P < .05). Infants who were breastfed also had higher Psychomotor Development Index scores than SF infants at age 6 months and slightly higher Preschool Language Scale-3 scores than MF infants at ages 3 and 6 months (P < .05). In addition, BF infants had a lower probability to score within the lower MDI quartile compared with MF infants and a higher likelihood to score within the upper quartile for the MDI and Psychomotor Development Index compared with SF infants.

CONCLUSIONS

This unique study showed that all scores on developmental testing were within established normal ranges and that MF and SF groups did not differ significantly. Furthermore, this study demonstrated a slight advantage of BF infants on cognitive development compared with formula-fed infants.

Breastfeeding and educational achievement at age 5

Our aim was to investigate whether the duration of breastfeeding, at all or exclusively, is associated with educational achievement at age 5. We used data from a prospective, population-based UK cohort study, the Millennium Cohort Study (MCS). 5489 children from White ethnic background born at term in 2000-2001, attending school in England in 2006, were included in our analyses. Educational achievement was measured using the Foundation Stage Profile (FSP), a statutory assessment undertaken by teachers at the end of the child's first school year. Breastfeeding duration was ascertained from interviews with the mother when the child was 9 months old. We used modified Poisson's regression to model the association of breastfeeding duration with having reached a good level of achievement overall (≥78 overall points and ≥6 in 'personal, social and emotional development' and 'communication, language and literacy' points) and in specific areas (≥6 points) of development. Children who had been breastfed for up to 2 months were more likely to have reached a good level of overall achievement [adjusted rate ratio (RR): 1.09, 95% confidence interval (CI): 1.01, 1.19] than never breastfed children. This association was more marked in children breastfed for 2-4 months (adjusted RR: 1.17, 95% CI: 1.07, 1.29) and in those breastfed for longer than 4 months (adjusted RR: 1.16, 95% CI: 1.07, 1.26). The associations of exclusive breastfeeding with the educational achievement were similar. Our findings suggest that longer duration of breastfeeding, at all or exclusively, is associated with better educational achievement at age 5.

Using a genetically informative design to examine the relationship between breastfeeding and childhood conduct problems

A number of public health interventions aimed at increasing the uptake of breastfeeding are in place in the United States and other Western countries. While the physical health and nutritional benefits of breastfeeding for the mother and child are relatively well established, the evidence for psychological effects is less clear. This study aimed to examine whether there is an association between breastfeeding and later conduct problems in children. It also considered the extent to which any relationship is attributable to maternally-provided inherited characteristics that influence both likelihood of breastfeeding and child conduct problems. A prenatal cross-fostering design with a sample of 870 families with a child aged 4-11 years was used. Mothers were genetically related or unrelated to their child as a result of assisted reproductive technologies. The relationship between breastfeeding and conduct problems was assessed while controlling for theorised measured confounders by multivariate regression (e.g. maternal smoking, education, and antisocial behaviour), and for unmeasured inherited factors by testing associations separately for related and unrelated mother-child pairs. Breastfeeding was associated with lower levels of conduct disorder symptoms in offspring in middle childhood. Breastfeeding was associated with lower levels of conduct problems even after controlling for observed confounders in the genetically related group, but not in the genetically unrelated group. In contrast, maternal antisocial behaviour showed robust associations with child conduct problems after controlling for measured and inherited confounders. These findings highlight the importance of using genetically sensitive designs in order to test causal environmental influences.

Traffic emissions are associated with reduced fetal growth in areas of Perth, Western Australia: an application of the AusRoads dispersion model

BACKGROUND

This study, in a region with relatively low industrial activity, used a highly specific marker for traffic emissions, accounted for the inherent fetal growth potential, and used complete record linkage of births, midwife notifications, deaths, hospital morbidity and birth defect records.

METHODS

Clinical records were obtained for pregnancies between 2000 and 2006 in three areas of Perth, Western Australia (n=3,501). We used carbon monoxide as a marker for locally derived traffic emissions, and assessed exposure using the AusRoads dispersion model. Fetal growth was characterised by proportion of optimal birth weight and investigated using multivariate mixed-effects regression.

RESULTS

Exposure in the third trimester was associated with a -0.49% (sd=0.23%) change in proportion of optimal birth weight per 10 μg/m(3) increase in locally derived traffic emissions. However, this result was confined to one of the three study areas due to elevated exposure misclassification among women in the other two areas. Among this group, a neonate who would have otherwise attained an optimal birth weight of 3.5 kg would be expected to be born 58 g lighter for an interquartile increase in third trimester exposure, which was approximately half of the effect observed for maternal smoking during pregnancy.

CONCLUSION

We observed an association between maternal exposure to traffic emissions and reduced fetal growth. This effect was supported by sensitivity analyses but only observed in one of the three study areas. Further studies are required to corroborate our results.

Long-term behavioural consequences of infant feeding: the limits of observational studies

Observational (non-experimental) studies of the association between infant feeding and subsequent child or adult behaviour are prone to residual confounding by subtle differences in psychological attributes and interactional styles of mothers who breast feed vs. those who formula-feed. We followed up 13,889 6.5-year-old Belarusian children who participated in a large cluster-randomised trial of a breast-feeding promotion intervention. Behaviour was evaluated using the Strengths and Difficulties Questionnaire (SDQ), completed independently by the children's parents and teachers. We compared the results of experimental (intention-to-treat, ITT) and observational analyses (based on feeding actually received), both adjusted for clustering. Observational analyses were additionally adjusted for geographical region, urban vs. rural residence, child's sex, age at follow-up, birthweight, and maternal and paternal education. No differences between the randomised experimental vs. control groups were observed in ITT analyses. In contrast, small but statistically significant associations with weaning prior to 3 months were observed for parent and teacher SDQ scores on total difficulties, conduct problems and hyperactivity, even after multivariable adjustment. The absence of associations based on ITT analyses, in contrast with the significant associations based on observed breast-feeding duration, strongly suggests that the latter are biased by residual confounding.

Breastfeeding and early child development: a prospective cohort study

AIM

Breastfeeding has been associated with multiple developmental advantages for the infant; however, there have also been a number of studies that find no significant benefits to child development. We examined the relationship between breastfeeding for 4 months or longer and child development at age 1, 2 and 3 years.

METHODS

Women were enrolled in the Western Australian Pregnancy Cohort (Raine) Study (N = 2900) and their live born children (N = 2868) were followed to the age of 3 years (N = 2280). Infant feeding data were collected at each age, and the mothers completed the Infant/Child Monitoring Questionnaire (IMQ), which measures progress towards developmental milestones in the domains of gross and fine motor skills, adaptability, sociability and communication. Factors adjusted for in multivariable analyses included maternal sociodemographic characteristics and stressful life events.

RESULTS

Infants breastfed for 4 months or longer had significantly higher mean scores (representing better functioning) for fine motor skills at age 1 and 3, significantly higher adaptability scores up to age two, and higher communication scores at age 1 and 3 years. Infants who were breastfed for <4 months were more likely to have at least one atypical score across the five developmental domains than those who were breastfed for 4 months or longer.

CONCLUSION

Although our effect sizes were small, breastfeeding for 4 months or longer was associated with improved developmental outcomes for children aged one to 3 years after adjustment for multiple confounding factors.