Research Update*Research updates summarize and critique current research. Where possible, critiques come from cited published articles or experts in the field. |
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Study Finds Improved Cognitive Development Among Preterm Infants with Supplementation of Docosahexaenoic and Arachidonic Acid A study in Pediatrics found that supplementation with docosahexaenoic acid (DHA) and arachidonic acid (AA) for very low birthweight infants (VLBW) fed human milk was associated with improved cognitive development. The study was a randomized, double-blind, placebo-controlled trial of 141 infants with very low birth weights (<1500 grams). Roughly half of the infants received the supplementation of 32 mg of DHA and 31 mg of AA per 100 mL of human milk for an average of nine weeks; the supplementation began one week after birth and lasted until the infant was discharged from the hospital. Cognitive development was assessed at 6 months by using the Ages and Stages Questionnaire and event-related potentials (ERP’s), which can measure recognition memory. The authors found no difference in growth or adverse events between the two groups, but found significant improvement on the problem-solving score, significant lower response times after a standard image, and no difference in responses to novel images. Higher levels of plasma fatty acids, including DHA and AA, were measured in the supplemented infants. The strengths of the study include a randomized, double-blinded study design, the multidisciplinary approach, and the use of ERPs to assess cognitive development. Limitations of the study include low statistical power for detecting differences and a high drop out rate; the authors estimated that at least 126 participants would be needed to detect significant differences between the groups; however, only 105 completed the six-month questionnaire. A larger sample size is desirable. The authors conclude that, “our present study is the first to show a beneficial effect on cognitive function of DHA and AA supplementation for VLBW infants fed human milk.” This study, however, only assessed infant development at six months and the authors conclude that, “it remains to be seen whether this type of intervention may have long-term effects on cognitive function.” * Henrisksen, C. Haugholt, K. Lindgren, M. et al. Improved Cognitive Development Among Preterm Infants Attributable to early Supplementation of Human Milk With Docosahexaenoic Acid and Arachidonic Acid. Pediatrics; 121; 1137-1145. New Study Suggests Preterm Boys May Not Benefit From Breastfeeding as much as Preterm Girls A study in June 2008 Pediatrics titled, “Differential Gender Response to Respiratory Infections and to the Protective Effect of Breast Milk in Preterm Infants” suggests that preterm boy infants with respiratory infections may not benefit from breast milk as much as preterm girls. The study, which followed 119 high-risk, very low birth weight infants in Argentina for the first year of life, found that breast milk significantly protected girls (n=55) but not boys (n=64) against severe acute lung disease; respiratory infections were most severe in girls who were not breastfed. However, there was no difference in the number of infections between the boys and girls, regardless of breastfeeding status. Although this study appears to have been performed according to high study management standards, several limitations exist. First, there are some limitations with the statistics. The sample size is very small; no a priori calculation of the number of subjects needed to show a significant difference was made to convince the reader that the sample size is large enough to detect significant differences. Additionally, this study examines four groups, breastfed and non-breastfed girls and boys; baseline demographics were only provided for only two groups (boys and girls) so that it could not be determined if differences among the four groups existed at baseline. Second, there are some nutritional limitations to this study. The definition of breastfeeding in this study was vague, as it included exclusive breastfeeding (n=4) and any breastfeeding but this amount was not quantified (frequency, duration, etc). Furthermore, no information was presented as to what other types of foods the breastfeeding group was receiving (preterm infants often receive supplemental sources of nutrition); further, there was no mention of infant formula feeding. Conclusions about infant formula, therefore, cannot be made. Likewise, due to the incomplete characterization of breastfeeding, making firm conclusions about the effects of breast milk per se is not possible. The duration of breastfeeding is not presented in relation to the timing of respiratory disease onset; therefore, one cannot tell if the breastfed subjects were receiving breast milk at the time of respiratory infections and what the effect might be. Another limitation is that the infants had very low birth weights and thus represent a very specialized subgroup of infants with specific nutritional needs. The generalizability of the study’s findings to term infants, as has been reported in the media recently, is therefore questionable. The authors conclude that “these findings suggest that breast milk protection is not universally conferred.” However, more studies are needed to determine if gender differences really do exist for respiratory infections and what those differences are. The results of this study should not change the current advice that breastfeeding is the ideal source of infant nutrition. *Klein, M. I., Bergel, E., Gibbons, L. et al. Differential Gender Response to Respiratory Infections and to the Protective Effect of Breast Milk in Preterm Infants. Pediatrics 2008; 121; e1510-e1516. Recent Studies Address Whether Breastfeeding Can Increase a Child's IQ A recent study by Kramer et al. published in Arch Gen Psychiatry in May 2008 provides evidence that breastfeeding promotion to mothers can results in infants with higher IQ than infants whose mothers receive no encouragement to breastfeed. The study design was a large randomized trial where some hospitals used baby friendly hospital practices to promote breastfeeding, whereas other hospitals did not. The mothers in each group were similar at entry regarding maternal education. Prolonged and exclusive breastfeeding was significantly increased in the intervention group, as was IQ of the children in this group at 6.5 years, as measured by two different scales of intelligence (Wechsler Abbreviated Scales of Intelligence (WASI) and teachers’ academic rankings). A strength of this study was the randomization of infants into two groups, which minimized any potential differences between infants. The randomization and the absence of differences in maternal education suggest comparable maternal IQ in the two groups and help to ensure the validity of the relationship between breastfeeding and IQ. One limitation due to the nature of the intervention (cluster hospital based) is that pediatricians who administered the IQ tests were not blinded to the intervention status of the children they examined. However, the authors also conducted blinded audits among a randomly selected subsample, and assessed scores of school performance among those children who had begun school, given by teachers who were blinded to treatment; these supplemental assessments gave similar results as obtained for the full cohort follow-up. The mechanism of how breastfeeding and IQ are related is unknown. Kramer states, “it remains unclear whether the observed cognitive benefits of breastfeeding are due to some constituent of breast milk or are related to the physical and social interactions inherent in breastfeeding.” More research on this topic is needed. *Kramer, M.S., Aboud, F., Mironova, E. et al. Breastfeeding and Child Cognitive Development. Arch Gen Psychiatry. 2008; 65: 578-584. Shorter Sleep Duration in Infancy is Associated with an Increased Risk of Childhood Overweight A recent study titled, “Short Sleep Duration in Infancy and Risk of Childhood Overweight” by Taveras et al. published in Archives of Pediatric Adolescent Medicine found that infants who slept for less than 12 hours a day were twice as likely to be overweight at three years of age than infants who slept greater than 12 hours a day. The authors followed 915 children from Project Viva, a prospective cohort study of maternal and offspring health outcomes of urban and suburban women, and asked mothers questions about their infant’s sleep habits at six months, one year, and two years of age. The authors adjusted their analysis for numerous factors that are independently associated with increased adiposity in children, including maternal education, income, prepregnancy BMI, marital status, prenatal smoking history, breastfeeding duration, child’s race, birth weight, 6 month weight-for length z score, daily television viewing, and daily active play. The authors conclude, that “strategies to improve sleep duration among young children may be an important component of behavioral interventions that promote childhood overweight prevention.” According to the authors, “this is the first study to report associations of infant sleep duration and child adiposity.” The study’s strengths include collecting longitudinal data on sleep duration from six months of age, using measured values of adiposity, such as subscapular and triceps skinfold thickness and height and weight, and adjustment for a number of sociodemographic and environmental predictors of childhood overweight. Some limitations of the study include recall of the mothers of their infants’ sleep habits, a high education and income level of study participants, and the inability to adjust for all possible confounders of this association. *Taveras, E.M., Rifas-Shiman, S.L., Oken, E., Gunderson, E.P., & Gillman, M.W. (2008). Short sleep duration in infancy and risk of childhood overweight. Arch Pediatr Adolesc Med 162, 305-311. International Expert Working Group recently recommended DHA and AA be added to Infant Formula The recommendations of an international group of experts, headed by Berthold Koletzko, that docosahexaenoic acid (DHA) and arachidonic acid (AA) should be added to infant formula were recently published in the Journal of Perinatal Medicine. In this publication, the authors state that “a large database exists concerning not only the safety, but also the efficacy of infant formula containing AA and DHA. These facts, together, support the addition of both AA and DHA when long chain poly unsaturated fatty acids (LC-PUFAs) are added to formula." The position paper outlines the benefits of DHA and AA, including visual and cognitive development and possibly lower mean blood pressure later in life. The publication recommends that infants receive these fatty acids from breast milk, but if an infant is not receiving breast milk, the levels of DHA and AA in breast milk can be matched with the addition of both of these fatty acids to infant formula. Furthermore, the paper recommends that “highly refined oils from single cell organisms (specific algal and fungal organisms), eggs, or fish as sources of DHA and/or AA are appropriate for use in infant formulae and weaning foods if the purity and safety of the specific oil used has been documented.” Noting that formula fed to infants containing DHA and AA does not alter infant growth, the group stated that “the addition of both DHA and AA to infant formula supports growth comparable to that seen in infants fed unsupplemented formula.” Additionally, the working group notes that “at least 0.2% of fatty acids as DHA appears necessary for achieving a benefit on functional endpoints, but DHA levels should not exceed 0.5% of fatty acids.” Based on analysis of recent literature, the members of the working group “unanimously agreed on the conclusions and recommendations provided here, which are supported by the World Association of Perinatal Medicine, the Early Nutrition Academy, and the Child Health Foundation.” These groups all support the addition of DHA and AA to infant formula. References Cited: * Koletzko, B, Lien, E, Agostoni, C. et al. The roles of long-chain polyunsaturated fatty acids in pregnancy, lactation and infancy: review of current knowledge and consensus recommendations. J. Perinat. Med. 2008; 36: 5-14. |
A Critical Evaluation of a Recent Study on the Impact of Commercial Hospital Discharge Packs on Breastfeeding A recent study, “Infant Formula Marketing Through Hospitals: the Impact of Commercial Hospital Discharge Packs on Breastfeeding” was published in the American Journal of Public Health in the February 2008 edition.1 In this study, the authors examined data from the 2000 and 2001 Oregon Pregnancy Risk Assessment Monitoring System (PRAMS), a population-based survey of postpartum women (n=3895), to determine the relationship between exclusive breastfeeding and the receipt of commercial hospital discharge packs (CHDPs). The authors reported that women who received CHDPs containing formula were more likely to exclusively breastfeed for fewer than 10 weeks than were women who had not received CHDPs. In addition, the authors reported that there was no association between nonexclusive breastfeeding for at least 10 weeks and a mother’s receipt of a CHDP. However, it is important to note that the authors report significant unadjusted odds ratios at 2, 6, and 10 weeks, but do not mention the results after adjustment for confounders at 2 and 6 weeks (only for 10 weeks), nor do they indicate if there were data for later points beyond 10 weeks in the survey for which no significant effects were found. This is not the first study to examine the receipt of CHDPs and infant feeding decisions. As the authors described, “since the early 1980s, there have been many studies, of widely varying quality and conclusions, of the impact of CHDPs on breastfeeding.” Of the five studies cited by the authors that compared receipt of discharge packs with formula versus receipt of no discharge packs or of discharge packs without formula, two studies showed an association and three studies showed no association respectively. The present study used a database of information that was over five years old (data from the 2000 to 2001 PRAMS survey). Infant feeding practices have changed over time. In fact, recorded breastfeeding rates in the United States have increased during the past decade, even as CHDPs have continued to be made available. It is not known how the present study, which is based on older data, may reflect current infant feeding decisions and practices. Another concern is that while the authors attempted to control for some variables that might have been associated with exclusive breastfeeding, such as education and maternal age, they did not report data on or control for other important variables, such as maternal employment. Maternal employment is one of the most common reasons women cite for cessation of exclusive breastfeeding. A 2006 study by Ryan et al. found that mothers who were not employed were more than twice as likely to breastfeed at six months than mothers who worked full time.2 Further, one third of mothers return to work within three months of giving birth and mothers cite “going back to work” as one of the most important reasons not to continue breastfeeding.2 The findings of this study could be explained by women returning to the workforce. Although some employers offer six weeks of paid maternity leave and the Family Medical Leave Act (1993) provides for up to 12 weeks of unpaid leave, the majority of working women in the United States are in hourly paid or minimum wage jobs and simply cannot afford not to work. 2 Furthermore, the authors also failed to control for smoking, which is a general indicator of maternal healthy behavior. The mothers who breastfed less than 10 weeks were much more likely to be smokers than those who breastfed for 10 weeks or longer. Given the small association found in this study, it is quite plausible that mothers exclusively breastfeed longer because they themselves were more health conscious, rather than any effect from receipt of a CHDP. Another limitation of this study is its retrospective design; the survey instrument was not designed for this purpose (i.e. measuring the impact of CHDPs). The authors acknowledged there was a potential for recall bias, as there were no data proving women could accurately remember receiving a CHDP. More importantly however, is that the receipt of a CHDP was not a random event. Both hospitals and health care professionals could choose whether and how to distribute CHDPs. Furthermore, mothers could choose whether to receive a CHDP or not. Some previous studies have attempted to control for this by intentionally providing or not providing CHDPs, or providing CHDPs with or without infant formula samples. The present study did not have such controls nor collected any data on how mothers had planned to feed their infants. The majority of mothers report they make the decision about how to feed their newborn baby before giving birth.3-5 In addition, most mothers (more than 9 out of 10) approve of “doctors, hospitals and clinics providing free samples of formula to new mothers.”5 It is not known whether in the present study, mothers who received CHDPs were actually more likely to choose to receive the CHDPs because they had already made the decision to not exclusively breastfeed for an extended period of time. The authors are correct to conclude that, in their study, causality cannot be established. In fact, while the authors acknowledge that for more than 40 years, formula manufactures have provided hospitals with CHDPs containing an infant formula sample, data show that during this same time, United States breastfeeding rates have significantly increased and reached record highs. Lastly, the data were not taken from a representative national sample but were representative of only one state, Oregon, which has the highest rates of exclusively breastfeeding women in the entire United States. Based on this limitation, the authors concluded that their study “cannot be generalized beyond Oregon.” Mothers should be allowed full access to all available information on infant feeding options and practices, as well as samples, where and when the mother and/or the infant’s healthcare provider find it appropriate. This enables informed infant feeding decisions. References Cited: 1 Rosenberg, K. D., Eastham, C.A., and Kasehagen, L. et al. Infant Formula Marketing Through Hospitals: the Impact of Commercial Hospital Discharge Packs on Breastfeeding. American Journal of Public Health. 2008; 98 (2): 290-295. 2 Ryan, A.S., Zhou, W., Arensberg, M.B. The effect of employment status on breastfeeding in 3Bailey, V., & Sherriff, J. Reasons for the early cessation of breastfeeding in women from lower socio-economic groups in Perth, Western Australia. Australian Journal of Nutrition & Dietetics. 1992; 49; 40-43. 4 Dix, D. Why women decide not to breastfeed. Birth. 1991; 18: 222-225. 5 Fairbank, Maslin, Maulin & Associates. National Survey on Infant Feeding. July/August 2005. |
Study shows no association between prolonged exclusive breastfeeding and childhood weight, adiposity, or blood pressure at age 6.5 years. A recent study showed that there were no significant association observed on various measures of adiposity and blood pressure in children who were exclusively breastfed for 6 months compared to those that were not after 6.5 years of follow up. The study, “Effects of prolonged and exclusive breastfeeding on child height, weight, adiposity, and blood pressure at age 6.5 y: evidence from a large randomized trial” by Dr. Michael Kramer was published in the American Journal of Clinical Nutrition in November, 2007. According to Dr. Kramer, this study “is the largest randomized trial ever done in the area of human lactation.” The study examined 13,889 children who had been selected at birth from 31 Belarussian maternity hospitals in the randomized Promotion of the Breastfeeding Intervention Trial (PROBIT). During the PROBIT trial, researchers recruited moms in maternity hospitals and clinics in Belarus who expressed a desire to start breastfeeding prior to birth. Dr. Kramer randomly assigned hospitals to implement breastfeeding promotion practices and standard care, as advised by the Baby Friendly Hospital Initiative. The intervention group was encouraged to breastfeed as long and as exclusively as possible, while the control group received no such support. Women in the intervention group breastfed significantly longer than women in the control group (the number of women who exclusively breastfed at three months was seven times higher in the intervention group). The follow-up took place from December 2002 to April 2005, when the children were six and a half years old. No significant intervention effects were observed for various measures of adiposity, including body mass index, height, waist or hip circumference, triceps or subscapular skinfold thickness, or blood pressure. The authors concluded that “prolonged, exclusive breastfeeding provides no apparent beneficial effects on stature, BMI, or other measures of adiposity, or blood pressure in 6.5 year-old Belarussian children.” The authors further stated that “previously reported beneficial effects on these outcomes may be the result of uncontrolled confounding and selection bias.” It is important to note that the population studied is a Belarussian cohort, which may have lower rates of obesity than the United States. Nonetheless, the authors conclude that “it seems unwise to depend on current efforts to promote exclusive and prolonged breastfeeding as an effective population health strategy for stemming the current obesity.” References Cited: * Kramer, M.S., Matush, L. Vanilovich, I. et al Effects of prolonged and exclusive breastfeeding on child height, weight, adiposity, and blood pressure at age 6.5 y: evidence from a large randomized trial. Am J clin Nutr 2007; 86: 1717-21. |
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Full Breastfeeding Duration and Risk for Iron Deficiency in U.S. Infants A study published in Breastfeeding Medicine suggests that infants fully breastfed for 6 months or more in the United States may be at increased risk of iron deficiency and anemia. This study analyzed data from two nationally conducted cross-sectional surveys, the National Health and Nutrition Examination Survey (NHANES) III, which took place from 1988-1994 and NHANES 1999-2002. Anemia and iron status were compared for five groups: formula fed only, full breastfeeding <1 month, full breastfeeding 1-<4 months, full breastfeeding 4-<6 months, or full breastfeeding > 6 months. Full breastfeeding was defined as the use of breastmilk as the overwhelming majority of the diet. The study found a five fold increased risk of low iron for infants fully breastfed for >6 months compared to those fully breastfed for 1 to <6 months and twice the risk of low iron compared to formula fed infants. The study found that NHANES III infants who were fully breastfed for >6 months had 3-5 times the risk of having a reported history of anemia compared to those fully breastfed for 1 to <6 months and twice the risk compared to formula fed infants. The association held up even when the analysis controlled for factors typically associated with iron deficiency, such as birth weight, demography, race/ethnicity, gender, socioeconomic, status, and education. The authors conclude that their finding “needs confirmation,” but recommend that physicians stress the importance of foods rich in iron to infants and children 6 months of age or older. For a more detailed discussion of this research, please click here. Chantry et al. Full Breastfeeding Duration and Risk for Iron Deficiency in U.S. Infants. Breastfeed Med; 2007; Jun; 2 (2): 63-73. Is Breast Really Best? A critical analysis of Breastfeeding Awareness Campaign A critical analysis of the U.S. Department of Health and Human Services (HHS) and the Ad Council’s National Breastfeeding Awareness Campaigns (NBAC) was published in the Journal of Health Politics, Policy and Law by Joan Wolf, Ph.D. of Texas A&M University. Launched in 2004, the NBAC showed images of pregnant women performing dangerous, irresponsible acts like mechanical bull riding and roller derby skating. These ads implied that the risks of not breastfeeding one’s infant were as great as the risk of harm of pregnant women engaging in these behaviors. According to Wolf, the NBAC neglected “fundamental ethical principles regarding evidence quality, message framing, and cultural sensitivity in public health campaigns.” These messages “consciously attempted to manufacture fear in order to increase breast-feeding rates,” rather than educate women to make the best feeding decision for their babies and for themselves. Thus, the NBAC capitalized on public misapprehension of risk; this approach, according to Wolf, can have deleterious effects. Besides evoking fear as a public health message, the NBAC cited inconsistent, inconclusive science as absolute. According to Wolf, “perhaps the most problematic dimension of the NBAC was the science on which it was based. Medical journals are replete with contradictory conclusions about the impact of breastfeeding… the notion that breast-feeding itself contributes to better health is far less certain, and this is a crucial distinction that breastfeeding proponents have consistently elided.” The type of studies upon which the NBAC was based are subject to confounding, according to Wolf, which “makes it difficult to isolate the protective powers of breast milk itself or to rule out the possibility that something associated with breast-feeding is responsible for the benefits attributed to breast milk.” Additionally, breastfeeding studies are subject to publication bias (the tendency for journals to publish studies that find associations over studies that find no association) and the potential bias of the expert review panels, which have preconceived notions about the superiority of breastfeeding. Given these problems, the “misrepresentation of medical research can lead to exaggerated and unethical claims in public health education.” According to Wolf, the NBAC was insufficiently attentive to the psychological, socioeconomic, and political concerns of its intended audience; women whose reasons for choosing not to breastfeed do not appear to have been given real consideration and were treated essentially as an agent of risk to their babies. In the campaign, unfounded scientific certainty served as justification for breastfeeding at all costs. Wolf suggests that future public health campaigns would benefit from more diverse review panels and from a greater focus on providing accurate risk information about probabilities and trade-offs in order to enable informed decision making. Wolf, JB. Is Breast Really Best? Risk and Total Motherhood in the National Breastfeeding Awareness Campaign. Journal of Health Politics, Policy and Law. Aug. 2007; 32 (4): 595-636. |
Improving rates of exclusive breastfeeding may be linked to education A study in the British Medical Journal found that antenatal (prior to birth) breastfeeding education and postnatal (after birth) lactation support both significantly increased the rates of exclusive breastfeeding up to six months after delivery. In this study, 450 healthy pregnant women in Singapore were randomized into one of three groups: a control group receiving routine care, an antenatal group receiving one breastfeeding education session prior to birth, and a postnatal group receiving two postnatal lactation sessions. Postnatal support was marginally more effective than antenatal education in improving exclusive breastfeeding rates, but both groups showed improved exclusive breastfeeding rates compared to the control group. Women receiving postnatal support were more likely than the control group to breastfeed exclusively at two weeks, six weeks, three months, and six months. Women who received antenatal education were more likely to exclusively breastfeed at six weeks, three months, and six months than the control group. In this study, since the rates of exclusive breastfeeding in the control group at six months were very low (9%), the findings may not be applicable to settings where there is a higher prevalence of exclusive breastfeeding at 6 months, such as the United States and Canada. Although this study suggests that hospital education about breastfeeding can improve exclusive breastfeeding rates, another randomized trial performed in the UK in 2004 with a greater number of women (750) found that offering lactation support did not significantly increase the prevalence of any breastfeeding to six weeks compared to a control group. 1 Su L. et al. Antenatal education and postnatal support strategies for improving rates of exclusive breast feeding: randomised controlled trial. BMJ August 1, 2007; 335; 596-599. http://www.bmj.com/cgi/content/full/335/7620/596 1 Graffy J, et al. Randomised controlled trial of support from volunteer couselors for mothers considering breast feeding. BMJ 2004; 328; 26. |
Effect of prolonged and exclusive breastfeeding on risk of allergy and asthma A recent study published in the September 11 British Medical Journal online found that prolonged and exclusive breastfeeding provided no protective effect against the risk of asthma and allergy. The study, titled “Effect of prolonged and exclusive breast feeding on risk of allergy and asthma: cluster randomized trial,” was performed by McGill University's Dr. Michael Kramer and funded by the Canadian Institutes of Health Research (CIHR). According to Dr. Kramer, this study “is the largest randomized trial ever done in the area of human lactation.” The study examined 13,889 children who had been selected at birth from 31 Belarussian maternity hospitals in the randomized Promotion of the Breastfeeding Intervention Trial (PROBIT). During the PROBIT trial, researchers recruited moms in maternity hospitals and clinics in Belarus who expressed a desire to start breastfeeding prior to birth. Dr. Kramer randomly assigned hospitals to implement breastfeeding promotion practices and standard care, as advised by the Baby Friendly Hospital Initiative. The intervention group was encouraged to breastfeed as long and as exclusively as possible, while the control group received no such support. The follow-up took place from December 2002 to April 2005, when the children were six and a half years old. Asthma and allergies were assessed via the international study of asthma and allergies in childhood (ISAAC) questionnaire as well as a skin prick test of five common allergens (house dust mite, cat, birch pollen, mixed northern grasses, and alternaria). The study found that the percentage of children who had allergies was approximately the same in both groups and there was no significant difference in the percentage of children with asthma. Additionally, there were “highly significant increases” in positive skin prick tests for all allergens tested among those who were exclusively breastfed for three or more months as compared to those exclusively breastfeeding for less than three months. One limitation of this study is that the prevalence of allergic symptoms were lower among PROBIT children than usually seen in the US and Canada. However, in 2002, another study, conducted among 1,037 New Zealand infants, found that babies who had been breastfed for more than four weeks had almost double the risk of contracting asthma and allergies in their childhood compared with counterparts who had been fed on infant formula.* According to Dr. Kramer, “In New Zealand, allergy and asthma are even more common than they are in Canada. This suggests that there is nothing unusual about the PROBIT setting that would explain our results." Therefore, the authors conclude that “public health measures to increase the initiation, duration, and exclusivity of breast feeding seem unlikely to have a major impact on reducing the incidence of atopic diseases.” Kramer MS et al. Effect of prolonged and exclusive breast feeding on risk of allergy and asthma: cluster randomized trial. British Medical Journal advance online publication 11 September 2007; doi: 10.1136/bmj.39304.464016.AE *Sears MR, Green JM, William AR, Taylor DR, Flannery EM, Cowan JO, Herbison GP, Poulton R, Long-term relation between breastfeeding and development of atopy and asthma in children and young adults: a longitudinal study. Lancet, 2002. 360 (9337): 901-7. |
A Longitudinal Study of Infant Feeding and Obesity Throughout the Life Course A Harvard research study, published in the April 2007 edition of International Journal of Obesity, found that women who were breastfed did not have lower incidence of overweight or obesity in adulthood when compared to women who were not breastfed. Researchers acknowledge that breastfeeding promotes the health of both mother and child but concluded, “it is unlikely to play an important role in controlling the obesity epidemic.” This conclusion is based on data collected on 35,526 women participating in the Nurse’s Health Study II (NHS). Information on infant feeding method was provided by the mothers of the NHS participants and was used to evaluate the relationship between infant feeding and the development of overweight and obesity throughout life. To date, the Harvard NHS study is the largest study examining breastfeeding and its influence on adult weight status. In addition to its large sample size, another strength of the study is the repeated measure of body mass index (BMI) during adult life. Further, the study finds that exclusive breastfeeding (for at least six months) is associated with leaner body shape at five years; however this association does not persist into adolescence or adulthood. The findings of this study contradict conclusions of previous epidemiologic studies that report a modest protective effect of breastfeeding on the development of adult overweight and obesity. When asked about these earlier studies, the lead researcher, Dr. Michels, on the Harvard study concluded, “many of those [previous] studies failed to properly account for socioeconomic factors that also may have had an influence [on adult weight].” Michels KB et al. A longitudinal study of infant feeding and obesity throughout life course. International Journal of Obesity. 2007; Jul. 31(7): 1078-85.http://www.nature.com/ijo/journal/v31/n7/full/0803622a.html Breastfeeding, Introduction of Complementary Foods, and Adiposity at 5 Years of Age A study published in the December 2006 edition of the American Journal of Clinical Nutrition concludes that no significant difference exists in the level of body fat among preschoolers who were breastfed compared to those who were formula fed. The study examines 313 children age 5 years. Measurements of body fatness were taken using dual-energy X-ray absorpitometry (DXA). These data, along with information provided by the mothers on infant feeding practices, were recorded along with other variables that potentially influence childhood overweight and obesity. Variables included race, gender, birth weight, and differences in the mothers’ socio-economic status, age, marital status, education level, smoking habits, and body mass index (BMI). The primary conclusion drawn from this research is that body fatness or adiposity is not related to the timing of introductory foods, the use of infant formula, or the duration and exclusivity of breastfeeding. This finding is consistent with two previous studies, also utilizing DXA data to determine differences in body fat levels in young children. Most studies showing a correlation between infant feeding method and risk of later overweigh or obesity use BMI to measure overweight or obesity in children. However, BMI is not the most accurate gauge of adiposity in young children. Body fat percent (BF%) is linked to the major health risks associated with obesity. Information from DXA is currently one of the best ways for measuring the BF%, and thus, provides better information to assess levels of overweight and obesity. Therefore, the authors of the study state health professionals should be “cautious about concluding that breastfeeding protects against later obesity solely on the basis of studies using BMI.” Burdette HL et al. Breastfeeding, introduction of complementary foods, and adiposity at 5 y of age. Am J Clin Nutr. 2006;83:550-8. Effects Of Fortified Milk On Morbidity In Young Children In North India: A November 2006 study published in the British Medical Journal indicates that fortified milks that contain immune-specific minerals and vitamins, such as follow-on formulas, growing up milks or toddler milks, may significantly reduce childhood morbidity in developing countries. Researchers examined the effect of fortified milk on the incidence of childhood illness and death due to lower respiratory tract infection (pneumonia), chronic or acute gastro-enteritis (diarrhea), and severe illness and high fever. Deficiencies in immunity-enhancing vitamins and minerals are widespread among children in developing countries. Fortified milks, which are commonly used internationally, are usually fed to young children, over 1 year of age, to improve their diets and assure nutritional adequacy. This recent study evaluated children between 1 and 3 years of age. The milk, fortified with zinc, iron, selenium, copper, and vitamins A, C and E reduced the incidence, as well as the number of days with severe illness. Further, the findings support the growing consensus that vulnerable groups, including preschool children, should be given additional zinc and iron. Using fortified milk (and other fortified complementary foods) is likely to be the preferred delivery route of these two nutrients in the preschool age population. Sazawal S et al. Effects of fortified milk on morbidity in young children in north India: community based, randomized, double masked placebo controlled trial. BMJ 2007;334:140, doi:10.1136/bmj.39035.482396.55. Effect of Breastfeeding on Intelligence in Children: A study published in the October 2006 edition of the British Medical Journal finds there is no difference in IQ between children who were breastfed compared to those who were formula fed. This study counters the findings of previous research in this area. Researchers examined data on 5,475 children of 3,161 mothers to assess the link between breastfeeding and child intelligence. This study measured IQ of the children using the Peabody individual achievement test (PIAT). This information was paired with data on infant feeding method provided by the mothers. The researchers took into account differences in maternal IQ, age, socioeconomic status and education level, and found that of all the variables, maternal IQ had the strongest influence on the intelligence of the child. Further, the study indicates that contradictory findings linking IQ with breastfeeding are based on research that fails to adjust for maternal intelligence. By adjusting for maternal IQ, the effect of breastfeeding on IQ is effectively eliminated. The study confirms that breastfeeding offers “an unequalled way of providing ideal food for the healthy growth and development of infants,” but improvements in a child’s intelligence cannot be included among those benefits. There is no measurable difference between the IQ of breastfed children compared to formula-fed children. Der G, Batty GD, Deary IJ. Effect of breast feeding on intelligence in children: prospective study, sibling pairs analysis, and meta-analysis. BMJ 2006:389786995, doi:10.1136/bmj.38978.699583.55. The Effect of Employment Status on Breastfeeding in the United States Research reported in the August 2006 edition of Women’s Health Issues indicates that women who are employed full-time are significantly less likely to initiate breastfeeding or to breastfeed their infants at all. Researchers based their conclusions on data examining the relationship between employment status and a mother’s decision to breastfeed. Though rates of breastfeeding are higher now compared to two decades ago, according to the study, full-time employment has a strong negative impact on a mother’s decision to breastfeed. Major factors affecting breastfeeding and full-time employment include lack of space or time to express breast milk, concerns about support from co-workers and employers, and real or perceived low milk supply. Researchers find that lactation programs in the workplace have positive outcomes on breastfeeding rates, absenteeism, productivity, morale, company loyalty and overall health care costs. In fact, 90 percent of employers on the 100 Best Companies for Working Mothers offer workplace lactation programs. Further, the study finds that timing of return to work has a strong influence on breastfeeding rates. Women with longer, paid maternity leaves, compared to unpaid maternity leaves, are more likely to initiate breastfeeding and to breastfeed for longer durations. In the United States, 63 percent of working women are either hourly paid or holding minimum wage jobs, and these positions are less likely to offer paid maternity benefits. Unpaid leave, for example the 12 weeks provided by the Family and Medical Leave Act, may not be an option for the majority of full-time working mothers due to financial constraints. The researchers leading the study suggest that costs of increasing maternity benefits to include paid leaves of absence could be offset by increased productivity, decreased absenteeism, lower health care costs, higher morale and improved company loyalty. In summary, breastfeeding goals for Healthy People 2010 may not be reached without greater support and improved programs for mothers who work full-time and wish to breastfeed. Ryan AS et al. The effect of employment status on breastfeeding in the United States. Women Health Iss. 2006;16:243-251. |