Clinical Scenario:
A 31-year-old G1P0 Female, currently 30 weeks pregnant with her first child, presents to the emergency department for GERD-like symptoms. During the encounter, while talking about her pregnancy, she expresses that she is currently considering whether she should breastfeed, or formula-feed the baby. She says that she has been reading articles online that say breastfeeding can help prevent certain health conditions, like asthma and food allergies. She asks for your advice/opinion on the matter.
Search Question:
Does breastfeeding help prevent the development of asthma in comparison to formula feeding?
PICO Table:
| Population | Intervention | Comparison | Outcome(s) |
| Pediatrics | Breastfeeding | Formula feeding | Development of asthma |
| Newborns | Human milk | Asthma during childhood | |
| Infants | |||
Search Strategy and Databases Used:
PubMed:
- Breastfeeding OR formula AND asthma: 30
- Formula feeding causing asthma in kids: 6
JAMA:
- Linking breastfeeding OR formula with childhood asthma: 6
JAMA Pediatrics:
- Breastfeeding AND childhood asthma: 5
Google Scholar:
- Linking breastfeeding or formula to asthma: 3,480
- Breastfeeding vs formular feeding and “childhood asthma”: 1,480 (Top results overlap heavily with PubMed)
I put the strength of the evidence first into consideration when selecting my final articles for inclusion. Because of the nature of my search question, when systematic reviews and meta-analyses were no longer available, chose to expand to include both randomized control trials and cohort studies. These types of studies would make it possible to compare breastfeeding directly to alternatives like formula feeding and the prevalence of asthma in children. I then considered how recently the articles had been published. Since they must have taken into account the most recent evidence, I favored articles that were published within the last five years.
Research Used:
Article 1: Breastfeeding and risk of childhood asthma: a systematic review and meta-analysis
| Citation | Xue, Mike, et al. “Breastfeeding and Risk of Childhood Asthma: A Systematic Review and Meta-Analysis.” ERJ Open Research, vol. 7, no. 4, 26 Aug. 2021, pp. 00504–2021., https://doi.org/10.1183/23120541.00504-2021. |
| Abstract | Objective: To investigate the relationship between breastfeeding and the development of paediatric asthma. Methods: A systematic review and meta-analysis was conducted with MEDLINE, Embase, CINAHL and ProQuest Nursing and Allied Health source databases. Retrospective/prospective cohorts in children aged <18 years with breastfeeding exposure reported were included. The primary outcome was a diagnosis of asthma by a physician or using a guideline-based criterion. A secondary outcome was asthma severity. Results: 42 studies met inclusion criteria. 37 studies reported the primary outcome of physician-/guideline- diagnosed asthma, and five studies reported effects on asthma severity. Children with longer duration/more breastfeeding compared to shorter duration/less breastfeeding have a lower risk of asthma (OR 0.84, 95% CI 0.75–0.93; I2 = 62.4%). Similarly, a lower risk of asthma was found in children who had more exclusive breastfeeding versus less exclusive breastfeeding (OR 0.81, 95% CI 0.72–0.91; I2=44%). Further stratified analysis of different age groups demonstrated a lower risk of asthma in the 0–2-years age group (OR 0.73, 95% CI 0.63–0.83) and the 3–6-years age group (OR 0.69, 95% CI 0.55–0.87); there was no statistically significant effect on the ⩾7-years age group. Conclusion: The findings suggest that the duration and exclusivity of breastfeeding are associated with a lower risk of asthma in children aged <7 years. |
| Link: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8666625/ |
Article 2: Infant milk-feeding practices and food allergies, allergic rhinitis, atopic dermatitis, and asthma throughout the life span: a systematic review
| Citation | Güngör, Darcy, et al. “Infant Milk-Feeding Practices and Food Allergies, Allergic Rhinitis, Atopic Dermatitis, and Asthma throughout the Life Span: A Systematic Review.” The American Journal of Clinical Nutrition, vol. 109, no. Supplement_1, 1 Mar. 2019, https://doi.org/10.1093/ajcn/nqy283. |
| Abstract | Background: During the Pregnancy and Birth to 24 Months Project, the USDA and Department of Health and Human Services initiated a review of evidence on diet and health in these populations. Objectives: The aim of these systematic reviews was to examine the relation of 1) never versus ever feeding human milk, 2) shorter versus longer durations of any human milk feeding, 3) shorter versus longer durations of exclusive human milk feeding prior to infant formula introduction, 4) feeding a lower versus higher intensity of human milk to mixed-fed infants, and 5) feeding a higher intensity of human milk by bottle versus breast with food allergies, allergic rhinitis, atopic dermatitis, and asthma. Methods: The Nutrition Evidence Systematic Review team con- ducted systematic reviews with external experts. We searched CINAHL, Cochrane, Embase, and PubMed for articles published between January 1980 and March 2016, dual-screened the results according to predetermined criteria, extracted data from and assessed the risk of bias for each included study, qualitatively synthesized the evidence, developed conclusion statements, and graded the strength of the evidence. Results: The systematic reviews numbered 1–5 above included 44, 35, 1, 0, and 0 articles, respectively. Moderate, mostly observational, evidence suggests that 1) never versus ever being fed human milk is associated with higher risk of childhood asthma, and 2) among children and adolescents who were fed human milk as infants, shorter versus longer durations of any human milk feeding are associated with higher risk of asthma. Limited evidence does not suggest associations between 1) never versus ever being fed human milk and atopic dermatitis in childhood or 2) the duration of any human milk feeding and allergic rhinitis and atopic dermatitis in childhood. Conclusions: Moderate evidence suggests that feeding human milk for short durations or not at all is associated with higher childhood asthma risk. Evidence on food allergies, allergic rhinitis, and atopic dermatitis is limited. |
| Link: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6500928/ |
Article 3: Effect of Avoiding Cow’s Milk Formula at Birth on Prevention or Asthma or Recurrent Wheeze Among Young Children: Extended Follow-up from the ABC Randomized Clinical Trial
| Citation | Tachimoto, Hiroshi, et al. “Effect of Avoiding Cow’s Milk Formula at Birth on Prevention of Asthma or Recurrent Wheeze among Young Children.” JAMA Network Open, vol. 3, no. 10, 2 Oct. 2020, https://doi.org/10.1001/jamanetworkopen.2020.18534. |
| Abstract | Importance: Children with food allergies may develop asthma or recurrent wheeze. Objective: To evaluate whether asthma or recurrent wheeze among children were changed by avoiding supplementing breastfeeding (BF) with cow’s milk formula (CMF) in the first 3 days of life. Design, Setting, and Participants: This randomized, unmasked, clinical trial was conducted at 1 university hospital in Japan beginning October 2013 with follow-up examinations occurring until January 2020. A total of 312 newborns at risk for atopy were randomized and assigned to either BF with or without amino acid–based elemental formula (EF) or BF with CMF, with follow-up examinations for participants showing signs of atopy conducted at 24 months. Follow-up examinations ran through January 2020. Interventions: Immediately after birth, newborns were randomly assigned (1:1ratio) to either breastfeeding with or without amino acid–based elemental formula for at least the first 3 days of life (no CMF group) or breastfeeding supplemented with CMF (5 mL/d) from the first day of life to 5 months of age (CMF group). Main Outcomes and Measures: Asthma or recurrent wheeze diagnosed by the pediatric allergy specialists of this trial; subgroups were stratified by serum levels of 25-hydroxyvitamin D and IgE. Results: Of 312 infants (156 [50.0% ] randomized to the no CMF group), 302 (96.8%) were followed up at their second birthday: 77 of 151 (51.0%) in the no CMF group and 81 of 151 (53.6%) in the CMF group underwent extended follow-up because of having atopic conditions. Asthma or recurrent wheeze developed in 15 (9.9%) of the children in the no CMF group, significantly less than the children in the CMF group (27 [17.9%]; risk difference, −0.079; 95% CI, −0.157 to −0.002). In participants with vitamin D levels above the median at 5 months of age, asthma or recurrent wheeze developed in 5 (6.4%) children in the no CMF group, significantly less than in the children in the CMF group (17 [24.6%]; risk difference, −0.182; 95% CI, −0.298 to −0.067; P for interaction = .04). In the highest quartile group of total IgE at age 24 months, asthma or recurrent wheeze developed in 2 children (5.3%) in the no CMF group, significantly less than the children in the CMF group (14 [43.8%]; risk difference, −0.385; 95% CI, −0.571 to −0.199; P for interaction = .004). Conclusions and Relevance: The findings of this study suggest that avoiding CMF supplementation in the first 3 days of life has the potential to reduce the risk of asthma or recurrent wheeze in young children, especially among those with high vitamin D or high IgE levels. |
| Link: | https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2771187 |
Article 4: Prospective Cohort Study of Breastfeeding and the Risk of Childhood Asthma
| Citation | Lossius, Anne Kristine, et al. “Prospective Cohort Study of Breastfeeding and the Risk of Childhood Asthma.” The Journal of Pediatrics, vol. 195, Apr. 2018, https://doi.org/10.1016/j.jpeds.2017.11.065. |
| Abstract | Objectives: To study whether the duration of breastfeeding and time for introduction of complementary foods was associated with the risk of childhood asthma. Study Design: We used data from the Norwegian Mother and Child Study, a nation-wide prospective cohort study which recruited pregnant women from across Norway between 1999 and 2008. Children with complete data of breastfeeding up to 18 months and current age >7 years were eligible (n=41 020). Asthma as the primary outcome was defined based on ≥2 dispensed asthma medications at age 7 years registered in the Norwegian Prescription Database. We used log- binomial regression models to obtain crude relative risks (RR) in the main analysis, and adjusted for selected confounders in multivariable analyses. Results: For duration of any breastfeeding, 5.9% of infants breastfed <6 months (adjusted relative risk [aRR] 1.05, 0.93-1.19) and 4.6% breastfed 6-11 months (aRR 0.96, 0.87-1.07) had dispensed asthma medications at 7 years as compared with 4.6% of infants breastfed ≥12 months (Ptrend 0.62). Infants still breastfed at 6 months, but introduced to complementary foods <4 months and 4-6 months, had an aRR of 1.15 (0.98-1.36) and 1.09 (0.94-1.27) respectively, as compared with infants fully breastfed for 6 months (Ptrend 0.09). Age at introduction of solids or formula separately were not significant predictors (Ptrend 0.16 and 0.08, respectively). Conclusion: We found no association between duration of breastfeeding or age of introduction to complementary foods and asthma at age 7. |
| Link: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5869148/ |
Article 5: Modes of Infant Feeding and the Risk of Childhood Asthma: A Prospective Birth Cohort Study
| Citation | Klopp, Annika, et al. “Modes of Infant Feeding and the Risk of Childhood Asthma: A Prospective Birth Cohort Study.” The Journal of Pediatrics, vol. 190, Nov. 2017, pp. 192–199., https://doi.org/10.1016/j.jpeds.2017.07.012. |
| Abstract | Objective: To determine whether different modes of infant feeding are associated with childhood asthma, including differentiating between direct breastfeeding and expressed breast milk. Study Design: We studied 3296 children in the Canadian Healthy Infant Longitudinal Development birth cohort. The primary exposure was infant feeding mode at 3 months, reported by mothers and categorized as direct breastfeeding only, breastfeeding with some expressed breast milk, breast milk and formula, or formula only. The primary outcome was asthma at 3 years of age, diagnosed by trained healthcare professionals. Results: At 3 months of age, the distribution of feeding modes was 27% direct breastfeeding, 32% breastfeeding with some expressed breast milk, 26% breast milk and formula, and 15% formula only. At 3 years of age, 12% of children were diagnosed with possible or probable asthma. Compared with direct breastfeeding, any other mode of infant feeding was associated with an increased risk of asthma. These associations persisted after adjusting for maternal asthma, ethnicity, method of birth, infant sex, gestational age, and daycare attendance (some expressed breast milk: aOR, 1.64, 95% CI, 1.12-2.39; breast milk and formula, aOR, 1.73, 95% CI, 1.17-2.57; formula only: aOR, 2.14, 95% CI, 1.37-3.35). Results were similar after further adjustment for total breastfeeding duration and respiratory infections. Conclusions: Modes of infant feeding are associated with asthma development. Direct breastfeeding is most protective compared with formula feeding; indirect breast milk confers intermediate protection. Policies that facilitate and promote direct breastfeeding could have impact on the primary prevention of asthma. |
| Link: | https://www.thrivediscovery.ca/uploads/8/9/1/2/89121762/klopp_2017_-_bf_modes___asthma__j_pediatrics.pdf |
Article 6: Breastfeeding and wheeze-related outcomes in high-risk infants: A systematic review and meta-analysis
| Citation | Harvey, Soriah M, et al. “Breastfeeding and Wheeze-Related Outcomes in High-Risk Infants: A Systematic Review and Meta-Analysis.” The American Journal of Clinical Nutrition, vol. 113, no. 6, 7 Apr. 2021, pp. 1609–1618., https://doi.org/10.1093/ajcn/nqaa442. |
| Abstract | Background: The risk of wheezing is high in infancy and is heightened in infants with a family history of asthma/atopy. The role of breastfeeding in influencing respiratory health for these high-risk infants is unclear. Objectives: To systematically appraise evidence for the association between breastfeeding and wheeze incidences and severity in high-risk infants. Methods: Studies identified through electronic databases and reference lists were eligible if they assessed breastfeeding and respiratory outcomes in infants with a family history of asthma/atopy. The primary outcome was wheeze incidences in the first year of life. Secondary outcomes were wheeze incidences in the first 6 months of life, indicators of wheeze severity (recurrent wheeze, health-care utilization, and medication use), and other wheeze-related outcomes [bronchiolitis, pneumonia, croup, and incidence of lower respiratory tract infection (LRTI)] up to 12 months old. Meta-analyses were conducted where possible. Results: Of 1843 articles screened, 15 observational studies met the inclusion criteria. Breastfeeding was associated with 32% reduced odds of wheezing during the first year of life (ever vs. never: OR, 0.68; 95% CI: 0.53, 0.88; n = 9 studies); this association was even stronger in the first 6 months (OR, 0.45; 95% CI: 0.27, 0.75; n = 5 studies). Breastfeeding for a “longer” versus “shorter” time (approximately longer vs. shorter than 3 months) was associated with 50% reduced odds of wheezing at the age of 6 months (OR, 0.50; 95% CI: 0.39, 0.64; n = 3 studies). Conclusions: Breastfeeding was associated with reduced odds of wheezing in high-risk infants, with the strongest protection in the first 6 months. More research is needed to understand the impact of breastfeeding intensity on wheezing and to examine additional respiratory outcomes, including wheeze severity. |
| Link: | https://academic.oup.com/ajcn/article/113/6/1609/6214420 |
Summary of Evidence:
| Author (Date) | Level of Evidence | Sample/Setting (# of subjects/ studies, cohort definition etc. ) | Outcomes Studied | Key Findings | Limitations and Biases |
| Xue, Mike, et al. (2021) | Systematic review and meta-analysis | 42 studies met inclusion criteria. Exclusive breastfeeding: Based on World Health Organization (WHO) criteria, where infants received only breastmilk with no other liquids or solids. Only studies with either physician-diagnosed asthma or appropriate strict guidelines for asthma definition were included. Alternatively, included studies could use secondary outcomes of asthma severity such as hospitalization, medication use and spirometry | Primary outcome: Diagnosis of asthma by a physician or using a guideline-based criterion. Secondary outcome: Asthma severity. | Children with exclusive breastfeeding for ⩾6 months compared to <6 months had a 30% lower risk of asthma. There is a reduced risk of asthma development in children with ⩾3 months of exclusive breastfeeding when compared with those <3 months. Additionally, any breastfeeding for ⩾3 months and ⩾6 months showed a significant benefit for asthma prevention. Babies who do not meet the 6 months of exclusive breastfeeding guidelines may still receive some protection against asthma development with partial or intermittent breastfeeding. | Observational data was restricted to cohort studies, limiting the total number of studies available. Limited data addressing maternal atopy and its influence on breastfeeding effects. Similarly, we were unable to stratify by sex, which has been highlighted as a risk factor in recent literature with evidence that childhood asthma severity and frequency are differentially affected by the pubertal stage between males and females [67]. |
| Güngör, Darcy, et al. (2019) | Systematic review | For search question 1 in the next column, twenty-one articles presented evidence about never versus ever being fed human milk and asthma in childhood. The evidence differed between the studies that included children only and the studies that included children as well as adolescents For search question 2, one cluster randomized controlled trial and seventeen prospective cohort studies that looked at asthma in childhood and adolescence. Search questions 3 through 5 did not yield any results that met inclusion criteria in this study. | Collectively, 5 search questions respectively compared: Never versus ever feeding human milk… Shorter versus longer durations of any human milk feeding… Shorter versus longer durations of exclusive human milk feeding prior to infant formula introduction… Feeding a lower versus higher intensity of human milk to mixed-fed infants… Feeding a higher intensity of human milk by bottle versus breast… …with food allergies, allergic rhinitis, atopic dermatitis, and asthma | These studies provided consistent evidence of an inverse association between the duration of any human milk feeding and asthma risk in children and adolescents. Findings suggest that longer durations of any human milk feeding are associated with higher relative risk of asthma in childhood and adolescence | Many of the articles used for search question 2 made generalizations of the US population, however they lacked racial and ethnic diversity. Infant milk feeding research can be prone to detection bias because infant milk-feeding data are often collected through the use of parent-reporting methods that may not be valid and reliable. Confounding can arise because differences between feeding groups are rarely mitigated by randomization (due to ethical issues around allocating infants to be fed less or no human milk) and infant-feeding decisions can be strongly socially patterned. |
| Tachimoto, Hiroshi, et al. (2020) | Randomized clinical trial | A total of 312 newborns at risk for atopy were randomized and assigned to either breastfeeding (BF) with or without amino acid–based elemental formula (EF) or BF with cow’s milk formula (CMF), with follow-up examinations for participants showing signs of atopy conducted at 24 months. | The primary outcome of this study was the incidence of asthma or recurrent wheeze based on the asthma predictive index. | In the overall study population, asthma or recurrent wheeze developed in 15 of 151 infants (9.9%) in the no CMF group, significantly less than in the CMF group (27 of 151 infants, 9.9%). The incidence of asthma or recurrent wheeze was not different among the no CMF group and the groups in which mothers switched from no CMF to CMF either within or after 14 days. In this RCT, by avoiding exposure to CMF for at least the first 3 days of life, the risk of asthma or recurrent wheeze appeared to have been decreased compared with supplementing with CMF from the first day of life. | Only participants with atopic conditions at their second birthdays were followed to the maximum age of 6 years. Asthma or recurrent wheeze could have developed in participants whose follow-up ended at their second birthday Second, the present study was conducted in a single center in Japan, so that the results may not be relevant for other racial/ethnic groups and countries with different food cultures. Last, this trial was performed in the central area of Tokyo. Participants tended to be in a high socioeconomic class, and their children may have a high risk of atopic disease such as food allergy. |
| Lossius, Anne Kristine, et al. (2018) | Prospective cohort study | 41,020 children with complete data of breastfeeding up to 18 months and current age >7 years were eligible. Children who had at least one dispensed prescription for asthma medications in the past year at the age of 7, in addition to a second dispensed prescription within 12 months of the first, were defined as asthma cases. Children were classified with asthma into 3 groups; early transient (asthma at only 3 years), late-onset (asthma onset after 3 years) and persistent asthma (asthma at both 3 and 7 years). | The primary outcome was current asthma at 7 years as defined based on dispensed prescriptions in the NorPD (Norwegian Prescription Database). Secondary outcome: Current asthma at 3 years and 7 years based on maternal report through questionnaire | The risk of asthma for children with no or any breastfeeding <6 months compared with ≥12 months was increased before adjustments. However, in the adjusted analysis, we observed no significant differences among categories. When looking at age for introduction of formula separately, the risk of asthma was increased when formula was introduced between 4-5.9 months as compared with 6 months or later. For early transient asthma, there was a significantly increased risk for children breastfed less than 6 months compared with 12 months or longer. There was no significant associations between duration of breastfeeding with late-onset asthma or persistent asthma. | The high prevalence of breastfeeding in the study limits the power to study the subgroup who did not receive breastmilk, but it provides a good opportunity to study duration of breastfeeding and the introduction of complementary foods. The accuracy of the asthma diagnosis is a limitation as there was no access to individual medical records to verify the diagnosis. The strict diagnostic criteria though should reduce risk of misclassification. |
| Kloop, Annika, et al. (2017) | Prospective cohort study | 3296 children in the Canadian Healthy Infant Longitudinal Development birth cohort. The primary exposure was infant feeding mode at 3 months, reported by mothers and categorized as direct breastfeeding only, breastfeeding with some expressed breast milk, breast milk and formula, or formula only | The primary outcome was asthma at 3 years of age, diagnosed by trained healthcare professionals. | At 3 months of age, the distribution of feeding modes was 27% direct breastfeeding, 32% breastfeeding with some expressed breast milk, 26% breast milk and formula, and 15% formula only. At 3 years of age, 12% of children were diagnosed with possible or probable asthma. Compared with direct breastfeeding, any other mode of infant feeding was associated with an increased risk of asthma. | There was an inability to quantify the relative proportion of direct breast milk, expressed breast milk, and formula provided, which precludes evaluation of dose effects. The frequency and timing of expressed milk feeding within the first 3 months was not reported, leading to potential exposure misclassification for feeding mode “at 3 months of age.” Although our asthma diagnosis was based on a structured history and physical examination, there can also be diagnostic uncertainty with that age group. |
| Harvey, Soriah, et al. (2021) | Systematic review and meta-analysis | 15 observational studies included a total of 9,164 infants with a family history of asthma/allergic disease. 13 were prospective cohort studies and 2 were retrospective. In 6 studies, 100% of the population had a family history of asthma/allergic disease. For the other 9 studies, the proportion of infants with a family history of asthma/allergic disease ranged from 12% to 79% of the study population; only data from the high-risk infants in these studies were used in this review. | The primary outcome was wheeze incidences in the first year of life. Secondary outcomes were wheeze incidences in the first 6 months of life, indicators of wheeze severity and other wheeze-related outcomes [bronchiolitis, pneumonia, croup, and incidence of lower respiratory tract infection (LRTI)] up to 12 months old. | Breastfeeding was associated with 32% reduced odds of wheezing during the first year of life and even stronger in the first 6 months Breastfeeding for a “longer” versus “shorter” time (approximately longer vs. shorter than 3 months) was associated with 50% reduced odds of wheezing at the age of 6 months. | Varying methods of data collection and different frequencies of follow-ups (weekly/fortnightly vs once or twice per year) for the outcome(s) of interest between studies. There were also different categories of breastfeeding duration and intensity examined, with some studies comparing ever breastfeeding with never breastfeeding, others comparing breastfeeding duration groups, and some comparing breastfeeding Exclusivity. |
Conclusion: (Briefly summarize the conclusions of each article then provide an overarching conclusion)
Article 1 (Xue, 2021): Both longer duration of any breastfeeding and exclusive breastfeeding is associated with a decreased likelihood of developing asthma, particularly in children aged <7 years. The results of longer duration of any breastfeeding demonstrated similar protective effects compared to prior reviews; however, this review is the first to clearly demonstrate a pooled protective effect of longer duration of exclusive breastfeeding.
Article 2 (Güngör 2019): Moderate evidence suggests that never, in comparison to ever, being fed human milk is associated with higher risk of childhood asthma.
Article 3 (Tachimoto 2020): In this RCT, by avoiding exposure to CMF for at least the first 3 days of life, the risk of asthma or recurrent wheeze appeared to have been decreased compared with supplementing with CMF from the first day of life.
Article 4 (Lossius 2018): The duration of breastfeeding is not associated with asthma at 7 years. Weaning before 6 months was associated with increased risk of asthma at age 3.
Article 5 (Kloop 2017): Any mode of infant feeding other than direct breastfeeding is associated with an increased likelihood of possible or probable asthma by 3 years of age. Compared with infants who received direct breast milk only, those who received some expressed milk had a 43% increased odds of this diagnosis, and those who received only formula had a 79% increased odds.
Article 6 (Harvery 2021): Breastfeeding ever versus never was shown to be protective against wheezing at 12 months of age in infants with a family history of asthma/allergy, reducing the odds of wheezing by 32%.
Overarching: Up until roughly six years of age, exclusive breastfeeding seems to be linked to a decreased risk of recurrent asthma-related symptoms. However, in the studies included, the protective impact of breastfeeding seems to be the largest in the first two years of life as opposed to later in childhood.
Clinical Bottom Line:
- Weight of the evidence – summarize the weaknesses/strengths of the articles and explain how they factored into your clinical bottom line (this may recap what you discussed in the criteria for choosing the articles)
- Article 1 (Xue, 2021) – The most recent and relevant systematic review and meta-analysis to my search question. Including 43 studies, this tracked incidence of the diagnosis of asthma when compared to the different variations of feeding. Additionally, these numbers were tracked through the first 7 years of life.
Article 2 (Güngör 2019) – Slightly older than the systematic review above, this article posed 5 different scenarios in which articles were included. Additionally, outcomes of asthma and the other diagnoses that were studied were tracked from birth through the first two years of life.
Article 6 (Harvey 2021) – A third systematic review and meta-analysis, though more recent than article 2, this review of 15 observational studies including over 9,000 infants, only tracked incidence and wheezing severity (not of the diagnosis of asthma) through the first year of life.
Article 3 (Tachimoto 2020) – Next highest on the evidence pyramid, a 7-year continuous follow-up of a RCT of 300 newborns. Each group adhered to these conditions until age 5 months and then followed up to their second birthdays. The population studied were newborns that were breastfed with and without supplementation of cow’s milk formula.
Article 4 (Lossius 2018) – While this prospective cohort study looked at over 40,000 children that were breastfed up to 18 months, asthma as a primary outcome was defined as having 2+ dispensed asthma medications at 7 years of age, not of an official diagnosis.
- Article 5 (Kloop 2017) – Another prospective cohort study, this was a smaller population than article 4 and only looked at the diagnosis of asthma by 3 years of age.
- Article 1 (Xue, 2021) – The most recent and relevant systematic review and meta-analysis to my search question. Including 43 studies, this tracked incidence of the diagnosis of asthma when compared to the different variations of feeding. Additionally, these numbers were tracked through the first 7 years of life.
Magnitude of any effects
Using the evidence from these studies, until roughly six years of age, exclusive breastfeeding seems to be linked to a decreased risk of recurrent asthma-related symptoms. However, the protective impact of breastfeeding seems to be the largest in the first two years of life as opposed to later in childhood. Nevertheless, the benefits of breastfeeding concerning the overall health of the child have been proven to outweigh any potential disadvantages.
Clinical significance (not just statistical significance)
According to the CDC, about 6 million children in the US (1 in 12) have asthma. Due to its high prevalence, vast research has been done to see if there are things that can be done from birth to lower its incidence later in life. For the first six months of an infant’s life, human milk is the best source of nutrients. Governmental and medical professional groups strongly advocate breastfeeding for all infants due to its recognized advantages in terms of nutrition, gastrointestinal function, immediate protection against infectious disease, and psychological well-being. Additionally, research has shown that breastfeeding reduces the number of clinically significant respiratory tract infections in infants and would therefore be expected to reduce wheezing associated with these infections.
