Extended Breastfeeding Research Paper

Abstract

BACKGROUND AND OBJECTIVES: There is mixed evidence from correlational studies that breastfeeding impacts children’s development. Propensity score matching with large samples can be an effective tool to remove potential bias from observed confounders in correlational studies. The aim of this study was to investigate the impact of breastfeeding on children’s cognitive and noncognitive development at 3 and 5 years of age.

METHODS: Participants included ∼8000 families from the Growing Up in Ireland longitudinal infant cohort, who were identified from the Child Benefit Register and randomly selected to participate. Parent and teacher reports and standardized assessments were used to collect information on children’s problem behaviors, expressive vocabulary, and cognitive abilities at age 3 and 5 years. Breastfeeding information was collected via maternal report. Propensity score matching was used to compare the average treatment effects on those who were breastfed.

RESULTS: Before matching, breastfeeding was associated with better development on almost every outcome. After matching and adjustment for multiple testing, only 1 of the 13 outcomes remained statistically significant: children’s hyperactivity (difference score, –0.84; 95% confidence interval, –1.33 to –0.35) at age 3 years for children who were breastfed for at least 6 months. No statistically significant differences were observed postmatching on any outcome at age 5 years.

CONCLUSIONS: Although 1 positive benefit of breastfeeding was found by using propensity score matching, the effect size was modest in practical terms. No support was found for statistically significant gains at age 5 years, suggesting that the earlier observed benefit from breastfeeding may not be maintained once children enter school.

  • Abbreviations:
    DHA —
    docosahexaenoic
    PSM —
    propensity score matching
    SDQ —
    strengths and difficulties questionnaire
    SEM —
    structural equation modeling
  • The medical benefits of breastfeeding for both mother and child are considered numerous and well documented.15 Yet the effect of breastfeeding on general cognitive abilities has been a topic of debate for nearly a century.6 The mechanism argued to be responsible for these effects is the nutrients found in breast milk.7,8 Two specific types of long-chain polyunsaturated fatty acids, namely docosahexaenoic (DHA) and arachidonic acid, have been implicated in both visual and neural development and functioning through neural maturation, which is important for cognitive abilities, such as problem solving.911

    The link with nutrients may also impact specific cognitive abilities like language development. For example, language abilities, such as vocabulary, are highly dependent on working and long-term memory given the consolidation and retrieval processes needed during acquisition.12,13 In rats, deficiency of fatty acids, such as DHA, during lactation resulted in poor memory retention during learning tasks, whereas supplementation of DHA had reversal effects.14 If the hypothesized “causal” mechanism of superior nutrition in breast milk is true, coupled with the specific impact of DHA on memory, breastfeeding should also impact language abilities. To date, ∼20 studies have investigated this association and all but 115 examined a combined measure of language (receptive and expressive) or receptive language only. There remains debate as to whether expressive and receptive language in early childhood form distinct modalities of language,16,17 raising the question of whether breastfeeding would be equally beneficial to each modality in the case of a 2-factor language model.

    Less studied is the impact of breastfeeding on behavior. Breastfeeding may lead to reduced behavioral problems as a result of early skin-to-skin contact, which helps form a secure mother-infant bond.18 Any effects of breastfeeding on cognitive and language development could also prevent the development of behavior problems. The absence of early behavior problems has social, economic, and medical value to society through reduced prevalence of delinquency, incarceration rates, and substance abuse,1921 making this an important area of research. With few exceptions, there remains a dearth of high-quality studies examining behavior,2225 and among them, consensus is not evident.

    Without randomization of mothers to breastfeeding and formula conditions, it is challenging to confirm the causal impact of these hypotheses. One study randomized the provision of a breastfeeding intervention, modeled on the Baby-Friendly Hospital Initiative, and found that the children of mothers in the intervention group had higher intelligence scores compared with controls at age 6 years.26 The strongest effects were for verbal intelligence. This study offers the best support to date for a causal link between breastfeeding and cognitive development. However, it is the only cluster randomized trial on human lactation.

    The majority of studies in this field are observational, thus the causal implications of breastfeeding are questionable given the inherent difficulty in controlling for selection into breastfeeding. For example, initial associations with cognitive development are often reduced after adjustments for confounders, such as parental education/IQ (ie, from an average 5-point to 3-point difference27), and, in some cases, the associations are no longer statistically significant.28 A variety of observational studies now apply quasi-experimental methods to better address the issue of selection bias, making inroads toward a better understanding of potential causal paths. The techniques used include propensity score matching (PSM), instrument variables, and sibling pair models. This study uses PSM because the sibling pair model limits the available pool of participants and instrument variables are extremely sensitive to the validity of the chosen instrumentation, which should be associated with the exposure but not with the outcome except for via the exposure.

    Using a large longitudinal population sample, we applied PSM, which mimics random assignment, in an effort to investigate the potential impacts of breastfeeding on children’s cognitive ability, expressive vocabulary, and behavior problems. Both breastfeeding duration and intensity were examined. Significant advantages for children who were breastfed, after matching, were expected for all outcomes. Grounded in the recommendations of the World Health Organization,29 it was expected that larger effect sizes would be observed for children who were fully breastfed and for longer durations.

    Methods

    Participants

    Participants included families enrolled in the Growing Up in Ireland infant cohort. Families with infants born between December 2007 and May 2008 were identified from the Child Benefit Register and randomly selected to participate. The overall recruitment response rate was 65% (N = 11 134). A detailed description of the study design can be found elsewhere.30 We used data collected at 9 months and 3 and 5 years of age. Only families with complete data for all confounders when children were 9 months and children who were born full term were included (N = 9854; 88.5% of the initial sample). Boys represented 50.6% (N = 4991) of the sample. Attrition across waves reduced the sample size to 8715 children at 3 years and 8032 at 5 years. Some children had missing data on the cognitive and vocabulary scales, resulting in 8535 and 8241 children respectively at age 3 and 7972 and 7942 children respectively at age 5. Additionally, missing teacher reports for behavior at age 5 years resulted in 7478 children being included in these analyses. Demographic characteristics of the families and rates of breastfeeding engagement can be found in Table 1 and Fig 1. Ethics approval was obtained from the Research Ethics Committee, Department of Children and Youth Affairs Ireland, and written consent was collected from parents/guardians before data collection.

    FIGURE 1

    The category “1” on the x-axis represents breastfeeding up to 31 days; “2” represents between 32 and 180 days; and “3” represents ≥181 days.

    TABLE 1

    Family, Maternal, Infant, and Medical Characteristics: Infant Cohort at 9 Months

    Measures

    Children’s cognitive abilities and expressive vocabulary were measured by using 2 scales from the British Abilities Scale31. The pictures similarities scale assessed problem-solving skills and the naming vocabulary scale assessed expressive vocabulary. The construct validity of each scale was derived by using the Wechsler Preschool and Primary Scale of Intelligence-Revised (r = 0.74 and 0.83, respectively).31 Standardized scores that adjusted for performance as compared with other children of the same age, with a mean of 50 and a SD of 10, were used. Age was adjusted in 3-month age bands.

    The Strengths and Difficulties Questionnaire (SDQ32) was used to assess children’s problem behaviors. The parent version was used at age 3 years and both the parent and teacher versions were used at age 5 years. The SDQ is comprised of 5 scales (emotional symptoms, conduct problems, hyperactivity/inattention, peer relationship problems, and prosocial behavior) with ratings of applicability of behaviors on a 3-point scale. A total difficulties scale is included, combining the 4 problem scales, to yield an overall difficulties score. We used the conduct problems, hyperactivity/inattention, and difficulties scales given our focus on externalizing problems. Validation of the SDQ has been extensively documented.33Table 2 reports the correlations between parent and teacher SDQ reports and the means and SDs for all child outcomes.

    Breastfeeding information was collected retrospectively when infants were 9 months old via maternal report. Support for the reliability of recall in previous breastfeeding studies has been established.34 However, given the lower reliability regarding the timing of the introduction of additional fluids/solids, Labbok and Krasovec’s definition of full (ie, exclusive or almost exclusive) and partial breastfeeding are used.35 Two breastfeeding variables were created to assess whether the infant was fully or partially breastfed and the duration of each. Mothers were asked 4 questions: “Was <baby> ever breastfed,” “How old was <baby> when he/she completely stopped being breastfed,” “Was <baby> ever exclusively breastfed,” and “How old was <baby> when he/she completely stopped being exclusively breastfed?” First, infants were grouped by breastfeeding status, both full and partial (5940) and never breastfed (3914). Of those who had ever been breastfed, 4795 had full breastfeeding at some point. Next, breastfeeding duration was grouped into 3 intervals; breastfed up to 31 days, 32 to 180 days, and ≥181 days. Each category of duration was treated as mutually exclusive, dummy coded, and compared against infants who had never been breastfed for the purpose of matching.

    Confounders have been suggested in part to account for the associations found between breastfeeding and child outcomes. We matched groups (breastfed, never breastfed) on 14 of the most pertinent factors. At the child level, factors included sex (boy/girl), birth weight (≥2500 g), and having neonatal intensive care (yes/no). At the maternal level, factors included age (≤24 years, 25–29 years, 30–34 years, or ≥35 years), highest level of education (primary level/no education, second level, or third level), working status before pregnancy (yes/no), ethnicity (Irish, any other white background, African or any other black background, Asian background, or other, including mixed background), depression (a score of ≥11 on the Center for Epidemiologic Studies Depression Scale), and type of delivery (vaginal or caesarean). Family-level factors included having a partner in the residence (yes/no), social class (professional/managerial, other nonmanual/skilled manual, or semiskilled/unskilled), medical card status (free medical care, free general practitioner care, or no free medical care), total number of household members who smoked during the pregnancy (none, or ≥1), and whether the cohort infant had siblings living in the household.

    TABLE 2

    Bivariate Correlations Between Parent and Teacher SDQ Scores and Means (SDs) of Children’s Outcomes at 3 and 5 Years of Age

    Statistical Analysis

    PSM reduces selection bias by matching children who were breastfed to children who were not, but who had a similar probability of being breastfed based on their measured characteristics. We used PSM logit models with nearest neighbor 1:1 matching techniques. In nearest neighbor matching, the sample is randomly ordered with matching occurring sequentially between the treatment (breastfed) and control (not breastfed) group based on participants’ propensity scores. Typically, the pair is then removed from the list and the next match is created. To ensure optimal matches, we imposed a caliper so that pairs could only be matched if the propensity score was within a tenth of a SD of the other. We also allowed matching with replacement given the low rates of longer durations and full breastfeeding in this cohort. Although matching with replacement has been argued to increase variance in the data, it also arguably reduces bias in the sample by ensuring better quality of matches.36 Balance checks in all models revealed substantial reductions of bias between matched groups on all individual confounders (ie, 0%–13.9% remaining bias in partial breastfeeding models, 0%–18.1% remaining bias in full models; data available on request). The remaining overall mean bias across models ranged from 3.2% to 8.5%. The ≤20% remaining bias has been suggested as the acceptable cutoff after matching.37 Thus, we concluded that the analytic matching technique resulted in good matches between conditions. Matching resulted in all participants falling within the area of common support. The average treatment effect on those who were treated (ie, children who were breastfed) is reported. Adjustments were made for multiple hypothesis testing by using the Holmes-Bonferroni method. All statistical analyses for PSM were conducted by using Stata version 13 software (Stata Corp, College Station, TX).

    To note, although PSM is advantageous in mimicking random assignment, a drawback is the challenge in evaluating a linear dose-response association, which has previously been found. Structural equation modeling (SEM) offers an alternative approach to examining this dose-response association. Additionally, SEM uses the full sample and has greater power. Thus, the data were also modeled by using SEM, where confounders were treated as correlated exogenous variables, the duration of breastfeeding was treated as a continuous mediating variable, and child outcomes were treated as correlated, which could be influenced by both breastfeeding and confounders. These results can be found in the Supplemental Material.

    Results

    Postmatching results for children fully breastfed up to 31 days revealed no statistically significant differences between groups on any outcome at age 3 or 5 years (Table 3). Similarly, for children who were fully breastfed between 32 and 180 days, no statistically significant differences were found for any outcomes at either age postmatching (Table 4). Finally, for children who were fully breastfed for ≥6, statistically significant differences were found postmatching for only 2 outcomes, problem solving and hyperactivity at age 3 years. Children who were fully breastfed scored 2.95 (SE = 1.39, P = .048) points higher on the problem-solving scale compared with children who were never breastfed and –0.84 (SE = 0.25, P ≤ .001) points lower on the hyperactivity scale. After adjustment for multiple testing, cognition was no longer statistically significant. However, children who were fully breastfed had slightly lower parent-rated hyperactivity compared with controls, and this remained statistically significant after adjustment (Table 5). Of note, results of the partial breastfeeding models were similar to the full models, however, after adjustment for multiple testing, neither cognitive ability nor hyperactivity at age 3 years remained statistically significant. These results can be found in the Supplemental Material.

    TABLE 3

    Full Breastfeeding up to 31 Days and Child Outcomes at 3 and 5 Years of Age: Pre- and Postmatching

    TABLE 4

    Full Breastfeeding 32 to 180 Days and Child Outcomes at 3 and 5 Years of Age: Results Pre- and Postmatching

    TABLE 5

    Full Breastfeeding ≥181 Days and Child Outcomes at 3 and 5 Years of Age: Results Pre- and Postmatching

    Discussion

    Without randomized controlled trials, the issue of causality will necessarily remain open, however the present results contribute important insights to the long-standing debate of potential “causal effects” versus artifacts of confounding that are not properly accounted for. This study also provides new perspectives on breastfeeding and children’s externalizing behavior. To the best of our knowledge, this is among the first studies to examine expressive vocabulary as an individual outcome and to consider externalizing behavior. It should be noted that our results apply only to infants born full term.

    After adjustment for multiple testing, the initial support found for breastfeeding and better problem solving at age 3 years if the child was breastfed for a minimum of 6 months was no longer statistically significant. In addition, no statistically significant effects were found for cognitive ability at age 5 years. These results are in contrast to some studies that have used PSM techniques to examine the effects of breastfeeding and general cognitive abilities.3840 However, differences in both analytical choices of the PSM approach used (eg, replacement, calipers) and differing selection of covariates may help to explain these differences across studies. Nonetheless, our findings were surprising in the context of the nutrients in breast milk being responsible for increased cognitive development. Regarding expressive vocabulary, no statistically significant advantages were observed for children who were breastfed at either age 3 or age 5.

    The limited research on breastfeeding and behavior problems is inconsistent, despite the relatively consistent reliance on the SDQ. Of interest, studies that have dichotomized the SDQ scales into abnormal scores (ie, at the 85th or 90th percentile) have not found statistically significant differences,2325 suggesting that breastfeeding is not likely to be a contributor to behavioral problems at clinical levels. When the SDQ scales are treated as continuous, small effects under certain conditions have been found.22 In this study, we treated all 3 scales as continuous and found that children who were fully breastfed for ≥6 months had lower parent-rated scores on the hyperactivity scale at age 3 years only. This result remained statistically significant after adjustment for multiple testing. Our results suggest that longer durations of breastfeeding might help to reduce hyperactive behaviors for children who display mild to moderate levels in the short term, but that these benefits are not maintained even in the medium term. This result would seemingly support the recommendation of the World Health Organization, suggesting that breastfeeding for at least 6 months is necessary for early gains to be observed.

    The inherent strengths of this study include the use of a particularly large longitudinal developmental dataset, the use of a quasi-experimental statistical approach, the use of a repeated measures design, the use of multiple informants and simultaneous standardized assessments thereby limiting potential shared method variance, the comparatively large number of confounders controlled (ie, 14) in contrast to previous studies (ie, an average of 7.7 ± 3.4 in higher-quality studies28;), and assessments in both cognitive and noncognitive domains of child development. Despite these strengths, some limitations must be noted. First, information on breastfeeding was collected retrospectively. Although the reliability of recall has been established,34 it must be acknowledged that recall bias may nevertheless be present, particularly regarding the duration of full breastfeeding. Second, only parent-reported SDQs were collected when children were 3 years of age. Studies have found that parents typically rate their children as having higher levels of problem behaviors as compared with teacher reports, with weak associations between these 2 types of informants,24 as was found in the current study for behavior ratings at age 5 years between parents and teachers. Having access to child care staff reports at age 3 years would have increased the reliability of the maternal-rated hyperactivity finding. Third, no information pertaining to direct breastfeeding versus expressed breast milk feeding was collected. Thus, it is not possible to investigate whether the association with reduced hyperactivity at age 3 years was the result of skin-to-skin contact or due to the nutrients in breast milk. This is an important direction for future studies examining behavioral outcomes. Fourth, although maternal education was included as a confounder, maternal IQ was not collected in this cohort. In the few studies that controlled for maternal IQ, the findings suggested that it accounted for a large part of the association between breastfeeding and cognitive outcomes.39,41 Thus, the inclusion of maternal IQ in future studies that employ PSM is warranted. Finally, PSM does not address selection on unobservables. Causal estimates may only be estimated by using PSM if selection is on observable characteristics or, in cases where unobservable factors influence selection into breastfeeding, the balancing on observables also balances on these unobservables. Despite these limitations, the results of this study add to the growing literature by showing that some statistically significant positive noncognitive benefits may result from longer durations of breastfeeding. Yet, beyond the statistical implications, the practical implications appear minimal and short lived. It is important to note, however, that these findings do not contradict the many medical benefits afforded to both mother and child as a result of breastfeeding.

    Acknowledgments

    We thank the Irish Social Science Data Archive for permission to use the infant cohort data from the Growing Up in Ireland study. We also thank the participants and their families for their long-term commitment to this study.

    Footnotes

      • Accepted January 17, 2017.
    • Address correspondence to Lisa-Christine Girard, PhD, School of Public Health, Physiotherapy, and Sports Science, University College Dublin, Geary Institute for Public Policy, Room B205, Belfield, Dublin 4, Ireland. E-mail: lisa.girard{at}ucd.ie
    • An earlier partial version of this work (age 3 data only) was presented as an oral presentation at the Growing Up in Ireland annual research conference; December 2015; Dublin, Ireland; and at 2 university seminar series; Life Course Centre, University of Queensland, Brisbane, Queensland, Australia and Melbourne Institute of Applied Economic and Social Research, Melbourne, Victoria, Australia; February 2016.

    • FINANCIAL DISCLOSURE: The authors have indicated they have no financial relationships relevant to this article to disclose.

    • FUNDING: Dr Girard is supported by a Marie Curie International Incoming Fellowship. The research that led to these results was funded by the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme FP7/2007-2013/ under the Research Executive Agency grant agreement 625014.

    • POTENTIAL CONFLICT OF INTEREST: The authors have indicated they have no potential conflicts of interest to disclose.

    • COMPANION PAPER: A companion to this article can be found online at www.pediatrics.org/cgi/doi/10.1542/peds.2017-0150.

    References

    What’s Known on This Subject:

    The medical benefits of breastfeeding for mother and child are considered numerous, yet the effect of breastfeeding on cognitive abilities remains largely debated given selection into breastfeeding. The effect on behavior is even less well understood.

    What This Study Adds:

    In applying quasi-experimental techniques which mimic random assignment, this study supports limited positive impacts of breastfeeding for children’s cognitive and noncognitive development. Although significant, the effect of breastfeeding on noncognitive development is small in practical terms.

    Abstract

    Lamaze International and Lamaze Certified Childbirth Educators are strong supporters of breastfeeding. This paper reviews eight recent studies that are related to breastfeeding and useful to clinicians and educators.

    Keywords: breastfeeding, childbirth education

    Lamaze International and Lamaze Certified Childbirth Educators are strong supporters of breastfeeding. The Lamaze International Teacher Education Program recommends that breastfeeding topics be discussed in more than one class in a childbirth education series. In this column, we present some recent research findings related to breastfeeding.

    Influences on Breastfeeding Duration

    The United States Health Resources and Services Administration and Centers for Disease Control have set a goal to have half of all newborns still breastfeeding at six months (U.S. Department of Health and Human Services, 2000). Several studies have focused on factors that may be related to the duration of breastfeeding. Ertem, Votto, and Leventhal (2001) studied 64 minority, low-income, single mothers in Connecticut and found that 70% had stopped breastfeeding after two months. More than 90% knew the benefits of breastfeeding. Almost none quit because the mother felt she was not producing enough milk. The mothers who quit early were less likely to believe they would breastfeed longer than two months and more likely to believe their infant preferred the bottle to their breast. The authors suggest that, in teaching about breastfeeding, an important focus should be placed upon enhancing a mother's confidence and changing beliefs about infant preferences.

    Labor Medication

    In another study that measured breastfeeding duration, researchers examined the effect of intravenous and epidural pain medications in labor on both duration and neonatal sucking among a sample of 129 mothers (Riordan, Gross, Angeron, Krumwiede, & Melin, 2000). Using the Infant Breast Assessment Tool, the authors found that a statistically significant difference in sucking existed between those women with no medication and those with either intravenous or epidural medication (p=.001). A statistically significant difference also existed between those women who had one type of medication and those who had both types of medication (p=.001). No difference was found between groups in the duration of breastfeeding measured at six weeks postpartum.

    … in teaching about breastfeeding, an important focus should be placed upon enhancing a mother's confidence and changing beliefs about infant preferences.

    Postpartum Support

    Porteous, Kaufman, and Rush (2000) conducted a randomized controlled trial in Toronto, randomly assigning 51 women to conventional postpartum nursing care or to individualized professional support that continued into the community. At four weeks postpartum, 68% of the women receiving conventional postpartum support continued to breastfeed, while 100% of the women receiving individualized support continued to breastfeed.

    At four weeks postpartum, 68% of the women receiving conventional postpartum support continued to breastfeed, while 100% of the women receiving individualized support continued to breastfeed.

    Complementary Feeding

    In another study, Black, Siegel, Abel, and Bentley (2001) tested the efficacy of an intervention designed to delay the early introduction of complementary feeding other than breast milk or formula. The focus of the intervention was the reduction of cultural barriers in order to promote the delay of introducing solid foods until four to six months postbirth, as recommended by the American Academy of Pediatrics, the World Health Organization, and Women, Infants, and Children programs. The sample consisted of 181 first-time, low-income, African American mothers who were under 18 years old and lived in multigenerational families. The sample was randomized to an intervention that included a home visit every other week for a year by one of two college-educated African American women, who were also mothers. A video was presented during the first visit, along with a specific curriculum and training. Black and colleagues (2001) found that the mothers of infants in the intervention group were four times more likely to delay the introduction of complementary feeding. Beyond the findings of the current study, the intervention model described in this paper may potentially be adapted to other areas where cultural barriers prevent behavior change.

    Benefits of Breastfeeding

    Another study examined one particular benefit of breastfeeding for a longer duration. Bener, Denic, and Galadari (2001) compared 117 children with acute lymphocytic leukemia or lymphoma with 117 healthy children. Those children who were breastfed for six months or less were 2.97 times more likely to develop a lymphoid malignancy than those children who were breastfed for more than six months. All of the children in this study were Bedouin Arabs, so replication of this research in other populations is necessary before the findings can be generalized.

    An additional advantage of breastfeeding was reported by Gillman et al. (2001). In a survey of 15,341 adolescents ages 9 to 14 (8,186 girls and 7,155 boys), the authors found that those who were fed predominantly breast milk in the first six months of life were 22% less likely to be overweight 9 to 14 years later. Moreover, adolescents who were breastfed for at least seven months were approximately 20% less likely to be overweight than those who were breastfed for three months or less. In suggesting that a long-term benefit of breastfeeding may be the prevention of overweight, the authors document yet another advantage.

    Dieting and Breastfeeding

    In their study, Lovelady, Garner, Moreno, and Williams (2000) addressed the subjects of weight and breastfeeding. Traditionally, women have been told not to restrict calories while breastfeeding because of the possibility of reducing the production of milk. Lovelady, a North Carolina nutritionist, and her colleagues studied 40 women from four to 14 weeks postpartum who were approximately 20% overweight. Lovelady reduced their diet by 500 calories a day and placed them on a supervised exercise program in which they initially walked 15 minutes each day and gradually increased to 45 minutes each day. The researchers in this study found that a weight loss of one pound per week did not affect the growth of the babies (the women lost an average of 10.5 pounds over the 10-week period).

    … a weight loss of one pound per week did not affect the growth of the babies [of breastfeeding mothers who were approximately 20% overweight].

    In a second study, Lovelady et al. (2001) examined whether or not women who were dieting and exercising had adequate levels of Vitamin B-6. Low levels of B-6 can affect growth and mental development in the baby and may play a role in depression in the mother. Eleven women with a 500-calorie restriction in their diets and 45 minutes of exercise per day were compared with 11 women who were not dieting and exercising. Both groups took the B-6 supplement. Both groups of women maintained healthy levels of B-6. Lovelady et al. (2001) recommended that women who are dieting and exercising should consider taking a B-6 supplement (2 mg/day), especially if they are not eating a diet rich in B-6. Foods rich in vitamin B-6 include fortified cereals, soybeans, wheat germ, tuna, salmon, and liver.

    Conclusion

    The studies reviewed in this article provide answers to a number of issues that may be addressed by childbirth educators. Does pain medication affect early suckling? It did in the study by Riordan and her colleagues (2000). Can intervention make a difference? Porteous and colleagues (2000) found that an intervention extended the duration of breastfeeding, while Black and colleagues (2001) found that their intervention delayed the introduction of solids. To an already formidable list of breastfeeding benefits, we can cautiously add a decrease in certain cancers (pending replication in populations more similar to those we teach) and prevention of adolescent overweight. And, finally, can women participate in a carefully designed weight loss program while they breastfeed and, at the same time, not cause harm to their infants? Lovelady and her colleagues (2000, 2001) suggest that the answer is “yes.”

    References

    • Bener A, Denic S, Galadari S. Longer breastfeeding and protection against childhood leukaemia and lymphomas. European Journal of Cancer. 2001;37:234–238.[PubMed]
    • Black M, Siegel E, Abel Y, Bentley M. Home and videotape intervention delays early complementary feeding among adolescent mothers. Pediatrics. 2001;107:67–71.[PubMed]
    • Ertem I, Votto N, Leventhal J. The timing and predictors of the early termination of breastfeeding. Pediatrics. 2001;107:543–548.[PubMed]
    • Gillman M, Rifas-Shiman S, Camargo C, Berkey C, Frazier L, Rockett H, Field A, Colditz G. Risk of overweight among adolescents who were breastfed as infants. Journal of the American Medical Association. 2001;285:2461–2467.[PubMed]
    • Lovelady C, Garner K, Moreno K, Williams J. The effect of weight loss in overweight, lactating women on the growth of their infants. New England Journal of Medicine. 2000;342:449–453.[PubMed]
    • Lovelady C, Williams J, Garner K, Moreno K, Taylor M, Leklem J. Effect of energy restriction and exercise on vitamin B-6 status of women during lactation. Medicine and Science in Sports and Exercise. 2001;33:512–518.[PubMed]
    • Porteous R, Kaufman K, Rush J. The effect of individualized professional support on duration of breastfeeding: A randomized controlled trial. Journal of Human Lactation. 2000;16(4):303–308.[PubMed]
    • Riordan J, Gross A, Angeron J, Krumwiede B, Melin J. The effect of labor pain relief medication on neonatal suckling and breastfeeding duration. Journal of Human Lactation. 2000;16(1):7–12.[PubMed]
    • U.S. Department of Health and Human Services. 2000. Healthy people 2010 (2nd ed.): With Understanding and Improving Health and Objectives for Improving Health (2 vols.). Washington, DC: U.S. Government Printing Office. Also available: www.health.gov/healthypeople.

    Articles from The Journal of Perinatal Education are provided here courtesy of Lamaze International

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