Why Are Breast Fed Babies Less Likelly to Get Infections

Pediatrics. 2014 Sep; 134(Suppl 1): S13–S20.

Breastfeeding and Adventure of Infections at half-dozen Years

Ruowei Li, Md, PhD, ^a Deborah Dee, PhD, MPH,^b Chuan-Ming Li, PhD,^c Howard J. Hoffman, MA,^c and Laurence M. Grummer-Strawn, PhD^a

Ruowei Li

Divisions of ^aNutrition, Physical Activeness and Obesity, and

Deborah Dee

^bReproductive Health, Centers for Affliction Command and Prevention, Atlanta, Georgia; and

Chuan-Ming Li

^cNational Institutes of Health, National Institute on Deafness and Other Communication Disorders, Division of Scientific Programs, Epidemiology and Statistics Plan, Bethesda, Maryland

Howard J. Hoffman

^cNational Institutes of Wellness, National Institute on Deafness and Other Communication Disorders, Division of Scientific Programs, Epidemiology and Statistics Program, Bethesda, Maryland

Laurence M. Grummer-Strawn

Divisions of ^aDiet, Concrete Activity and Obesity, and

Abstract

Background:

Previous studies accept shown that breastfeeding is associated with reductions in the hazard of mutual infections among infants; notwithstanding, whether breastfeeding confers longer term protection is inconclusive.

METHODS:

Nosotros linked data from the 2005–2007 IFPS 2 (Babe Feeding Practices Report II) and follow-up data nerveless when the children were 6 years former. Multivariable logistic regression was used, controlling for sociodemographic variables, to examine associations of initiation, duration, exclusivity of breastfeeding, timing of supplementing breastfeeding with formula, and breast milk intensity (proportion of milk feedings that were breast milk from age 0–half dozen months) with maternal reports of infection (cold/upper respiratory tract, ear, throat, sinus, pneumonia/lung, and urinary) and ill visits in the past year among 6-year-olds (North = 1281).

RESULTS:

The most mutual past-year infections were colds/upper respiratory tract (66%), ear (25%), and throat (24%) infections. No associations were establish betwixt breastfeeding and colds/upper respiratory tract, lung, or urinary tract infections. Prevalence of ear, throat, and sinus infections and number of ill visits differed according to breastfeeding duration, exclusivity, and timing of supplementing breastfeeding with formula (P < .05). Among children ever breastfed, children breastfed for ≥ix months had lower odds of past-year ear (adjusted odds ratio [aOR]: 0.69 [95% confidence interval (95% CI): 0.48–0.98]), throat (aOR: 0.68 [95% CI: 0.47–0.98]), and sinus (aOR: 0.47 [95% CI: 0.30–0.72]) infections compared with those breastfed >0 to <3 months. Loftier chest milk intensity (>66.six%) during the showtime 6 months was associated with lower odds of sinus infection compared with low breast milk intensity (<33.3%) (aOR: 0.53 [95% CI: 0.35–0.79]).

CONCLUSIONS:

This prospective longitudinal study suggests that breastfeeding may protect confronting ear, throat, and sinus infections well beyond infancy.

Keywords: breastfeeding, infection, Infant Feeding Exercise Study II, Year half dozen Follow-Up Report

Homo milk is the all-time source of nutrition for most newborns and infants.¹ In improver, homo milk provides immunologic protection against many infections during infancy.² Given the importance of breastfeeding for the wellness and well-being of mothers and children, the American Academy of Pediatrics recommends breastfeeding for at least 12 months, continued afterward as long as mutually desired by the female parent and child.ⁱⁱⁱ Information technology is well known that human milk contains an array of antimicrobial, antiinflammatory, immunomodulatory, and bioactive molecules and compounds that contribute to its protections confronting infections.ⁱ The mechanisms through which breastfeeding could have an impact on communicable diseases are multiple, including promoting mucosal maturation, balancing the gut microflora, interfering with the attachment of antigens to epithelial cells, stimulating neonatal immune systems, and limiting exposure to the germs from foreign dietary antigens.⁴ ^, ⁵

What is not well understood is whether early consumption of human milk confers long-term benefits confronting infections years after lactation is terminated. It has been suggested that breastfeeding may protect against Helicobacter pylori colonization,^{half dozen} ^– ⁸ Haemophilus influenzae type b infection,⁹ and acute appendicitis and recurrent tonsillitis requiring tonsillectomy afterward in life.¹⁰ ^, ^xi Wheezing affliction has been shown to be decreased for up to six to vii years after the termination of breastfeeding compared with nonbreastfeeding.¹² ^– ^fourteen Wilson et al¹⁴ too demonstrated that children who had been exclusively breastfed for 15 weeks remained better protected against respiratory tract infections for ∼seven years compared with those not breastfed. Saarinen¹⁵ found that any corporeality of breastfeeding for 3 to 4 months decreased the risk of developing otitis media upward to the age of 3 years, whereas Howie et al¹⁶ found that any breastfeeding for at least 13 weeks was not associated with ear infection but was associated with a significantly lower prevalence of gastrointestinal disease in the first two years of life compared with those who were never breastfed or breastfed <13 weeks.

The purpose of the nowadays study was to examine the associations between breastfeeding practices during infancy and various infections at 6 years of age by using data from a longitudinal study in the U.s.a..

Methods

Sample

IFPS Ii (Baby Feeding Practices Report 2), a big longitudinal study conducted by the United states Food and Drug Administration and the Centers for Disease Control and Prevention in 2005–2007, followed up mothers from late pregnancy until ane year afterwards birth by using almost monthly mail surveys during infancy. Mothers enrolled in IFPS II were re-contacted by mail in 2012 to collect in-depth information on their children's diet, schoolhouse services, and behavioral and health outcomes at six years of age. Linking data from IFPS 2 to Y6FU (Year half dozen Follow-Upwardly Study), we identified 1542 mother–child pairs with data from both studies. Detailed information on survey assistants and data collection of Y6FU are available elsewhere in this supplement.¹⁷

Outcome Measures

The primary result measures for our study were infections and the number of sick visits reported past mothers when their children were six years old. Information on children's infections were obtained past asking: "During the past 12 months, how many times did your half-dozen-year-old have the following infections?" The multiple choices on the listing included "ear infection; sinus infection; throat infection, similar strep throat; pneumonia or lung infection; urinary tract infection; and cold or upper respiratory infection." Data on sick visits were obtained past asking: "During the past 12 months, how many times did you accept your 6-twelvemonth-old to a doctor or other health professional for any of the following reasons?" Ill visit was i of the reasons listed in improver to routine well-kid visit, follow-up visit, and emergency department visit due to illness. For each question on infection and ill visit, response options were either "none" or the "number of times (1, two, iii, 4, 5, 6 or more times)" occurred in the past 12 months. We dichotomized each infection into "0" or "≥1" time during the past 12 months, with "0" as the referent. Considering ∼70% of children had at least 1 sick visit during the past 12 months, we dichotomized sick visit every bit "0–2" or ">2" times, with "0–2" every bit the referent.

Main Exposures

Breastfeeding practices were categorized according to initiation, elapsing, exclusivity, intensity of breastfeeding, and timing of supplementing breastfeeding with formula. Breastfeeding initiation was based on the IFPS II neonatal survey question "Did you ever breastfeed or try to breastfeed your baby, either in the hospital or birth center, or after you went home?" Other breastfeeding measures were developed but among mothers who initiated breastfeeding. Breastfeeding elapsing to any extent was obtained past using two questions in each postpartum survey of IPFS Ii (∼1, 2, iii, 4, five, half-dozen, 7, 9, x.5, and 12 months of historic period): "Have you completely stopped breastfeeding and pumping milk for your infant?" and, if yes, "How onetime was your baby when y'all completely stopped breastfeeding and pumping milk?" We then categorized breastfeeding duration into >0 to <3, 3 to <6, six to <ix, and ≥nine months. Exclusive breastfeeding information were obtained by asking almost the frequency of liquids (including breast milk, formula, other milks, juices, carbohydrate sweet beverages, and water) and foods the infant was fed during the by 7 days at each postpartum survey. Exclusive breastfeeding was defined for each survey as chest milk only without whatever other liquids or solids fed to infants in the by vii days; we estimated its elapsing as the midpoint of infant ages between the last questionnaire when the mother indicated sectional breastfeeding and the first questionnaire when she indicated nonexclusive breastfeeding. Exclusive breastfeeding duration was categorized into >0 to <iv, 4 to <6, and ≥6 months, simply information technology was coded every bit "unknown" if infants left the surveys earlier 6 months while exclusively breastfeeding (n = 22). To test whether the timing of formula introduction while breastfeeding is associated with infections, a composite variable was created amidst mothers who initiated breastfeeding: breastfeeding <six months with formula supplemented earlier 6 months, breastfeeding ≥half dozen months with formula supplemented before half-dozen months, and breastfeeding ≥six months without formula supplemented earlier 6 months. To test whether infection was associated with chest milk intensity, defined as the percent of milk feedings that were chest milk ([number of breast milk feedings/(breast milk + formula + cow's milk + other milk feedings) × 100%]), nosotros calculated the mean percentage of milk feedings being chest milk during the first vi months and further categorized it as low (>0% to <33.3%), medium (33.3% to 66.6%), or high (>66.vi%) chest milk intensity.

Other Measures

To command for potential misreckoning furnishings, we adjusted for a series of maternal and child characteristics from IFPS Two and Y6FU as shown in Table 1. All maternal sociodemographic variables were from IFPS Two, including maternal age (18–24, 25–29, 30–34, or ≥35 years); maternal race/ethnicity (not-Hispanic white, non-Hispanic black, Hispanic, or other); maternal education (≤loftier school, some college, or college graduate); household income as poverty income ratio according to 2008 census definitions (<185%, 185%–349%, or ≥350%); marital condition (yes or no); parity (primiparous or multiparous); postpartum participation in the Special Supplemental Diet Programme for Women, Infants, and Children program; and prepregnancy BMI (<xviii.5, 18.5–24.9, 25.0–29.nine, or ≥xxx.0). Infant covariates were from IFPS 2, including gender, birth weight (≤4000 or >4000 g), and babe care assessed by whether the baby was cared for by someone other than the parent on a regular schedule during the past 4 weeks at the calendar month 3 survey (yep, no, or unknown). Both child covariates were from Y6FU, including whether the child attended after-school child intendance that was outside the home and the blazon of school the child attended at vi years of age (public, individual, or abode based).

Table ane

Prevalence of at Least i Occurrence of Infection in the By Twelvemonth Among 6-Year-Onetime U.s. Children According to Maternal, Babe, and Child Characteristics, IFPS II (2005–2007) and Y6FU (2012)

Variable	N	Past-Year Infections at Age 6 Years (%)
Variable	N	Common cold or Upper Respiratory Tract	Ear	Throat	Sinus	Pneumonia or Lung	Urinary Tract
Full	1281	65.7	25.one	23.7	15.6	4.6	3.viii
Maternal historic period, y
18–24	178	60.7	27.5	23.6	15.two	3.9	three.4
25–29	416	66.6	25.vii	24.3	13.7	5.five	iv.3
30–34	426	69.vii	21.six	25.ane	eighteen.1	5.2	4.2
≥35	261	61.3	28.0	20.7	14.9	ii.7	2.7
Race/ethnicity
White	1119	66.vii	25.7	24.7	16.i	4.5	4.0
Black	42	57.ane	21.four	16.7	9.5	7.one	0.0
Hispanic	68	57.4	23.five	xix.i	14.seven	ii.9	four.four
Other	52	63.5	15.iv	15.4^a	11.5	7.7	i.nine
Maternal education
≤High school	207	61.8	30.4	21.seven	19.iii	ane.9	3.9
Some college	467	64.7	25.1	23.8	16.1	6.2	four.three
College graduate	607	67.ix	23.2	24.iv	14.0	four.3	3.five
Poverty–income ratio, %
<185	438	61.0	26.nine	21.7	17.viii	3.vii	4.3
185–350	490	65.ix	24.7	26.9	13.7	5.3	3.vii
>350	353	71.4^a	23.2	21.8	15.6	4.8	3.four
Married
No	205	61.0	22.9	18.1	fifteen.6	4.iv	5.9
Yes	1076	66.6	25.five	24.viii^a	15.6	4.7	3.4
Parity
Primiparous	352	69.6	23.iii	26.i	15.6	5.one	5.ane
Multiparous	929	64.iii	25.seven	22.8	fifteen.half dozen	4.iv	3.3
Postpartum WIC participation
Yes	388	61.nine	28.6	23.seven	17.viii	four.1	iv.four
No	893	67.4	23.5	23.7	14.vii	four.eight	iii.6
Prepregnancy BMI
Underweight (<18.5)	48	72.ix	22.ix	31.iii	18.8	8.three	6.iii
Normal (18.v–24.ix)	577	66.9	22.5	23.1	13.5	3.6	3.half dozen
Overweight (>25.0–29.nine)	329	67.5	28.3	21.0	xiv.vi	6.7	3.iii
Obese (≥xxx.0)	327	sixty.9^a	26.vi	26.6	19.ix^a	3.seven	iv.3
Infant's gender
Male person	630	66.five	25.1	23.five	15.iv	3.3	0.8
Female	651	65.0	25.0	24.0	15.8	5.8^a	6.8^a
Birth weight, g
≤4000	1117	65.7	25.1	23.6	xv.5	4.seven	3.9
>4000	164	65.9	25.0	24.4	xvi.v	iii.seven	3.7
Infant cared for by someone other than parent at 3 mo
Yes	388	67.0	25.iii	27.1	21.4	3.4	2.8
No	738	66.4	25.3	22.viii	13.4	five.eight	4.vii
Unknown	155	59.4	23.2	xx.0^a	xi.6^a	1.9	one.9
Attend subsequently-schoolhouse child intendance at 6 y
Yeah	347	67.7	24.v	25.7	sixteen.4	6.one	4.0
No	934	65.0	25.three	23.0	fifteen.3	four.1	3.8
School type at half-dozen y
Public	1049	65.vii	26.2	25.seven	15.6	4.7	3.8
Private	156	67.3	25.6	21.3	18.0	v.i	3.ix
Home-based	76	63.two	7.9^a	1.3^a	x.5	ii.6	4.0

Statistical Analysis

Α χ² test was used to examine the rough relationships between infections and breastfeeding practices, with P < .05 as the cutoff for statistical significance. Multivariable logistic regression analyses were used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs) of by-year infection in 6-twelvemonth-olds according to various breastfeeding practices after adjusting for the aforementioned misreckoning variables. Similarly, χ² tests and multivariable logistic regression analyses were applied to examine the relationships between various breastfeeding practices during infancy and the likelihood of seeing a physician for a sick visit during the past 12 months at vi years of age. All statistical analyses were performed by using SAS version 9.3 (SAS Institute, Inc, Cary, NC).

Results

Amongst 1542 female parent–child pairs who participated in both IFPS II and Y6FU, 5% (n = 73) did not study on infections at half dozen years of historic period, and 2% (n = 34) had missing data on breastfeeding practices during infancy. After excluding an additional 10% (n = 154) who were missing data on the covariates, the final analytical sample included 1281 female parent–child pairs with complete data. Women excluded considering of missing data were more likely to have only a high school didactics or less (19.5% vs 16.2%; P = .03) and exist a participant in the Special Supplemental Diet Programme for Women, Infants, and Children (39.9% vs xxx.two%; P < .01) but less probable to have their kid attend child care at iii months of age (22% vs 34%; P < .01). There were no significant differences for all other comparisons (data not shown).

Amidst 6-year-old children, 66% had at least 1 cold or upper respiratory tract infection, 25% had at least 1 ear infection, 24% had at least 1 throat infection, and 16% reported at least 1 sinus infection in the previous 12 months. Both pneumonia or lung infection and urinary tract infection were relatively uncommon (5% and 4%, respectively) (Table 1). Maternal characteristics that were significantly associated with children's past-year infections reported at age 6 years were maternal race/ethnicity and marital condition (for pharynx infection), poverty–income ratio (for cold or upper respiratory tract infection), and prepregnancy BMI (for common cold or upper respiratory tract and sinus infection). Child characteristics that were significantly associated with by-year infections were infant gender (for pneumonia or lung and urinary tract infection) and type of school the child attended at age 6 years (for ear and throat infection) (P < .05 based on χ² tests). Specifically, boys had a lower prevalence of pneumonia or lung infection (3.3% vs 5.eight%) and urinary tract infection (0.8% vs 6.eight%) than girls. The proportions of ear and throat infections reported past mothers were everyman among children who were beingness home-schooled.

In this study, 86% of mothers initiated breastfeeding. Among them, 28% stopped breastfeeding earlier iii months, and 79% stopped exclusive breastfeeding earlier 4 months (Table 2). Common cold or upper respiratory tract infection, pneumonia or lung infection, and urinary tract infection was not significantly associated with any infant feeding measures. However, the proportion of vi-twelvemonth-old children reported to accept past-year throat and sinus infections was lower among ever-breastfed children. When the relationships between breastfeeding and infections were examined only amid children who initiated breastfeeding, meaning associations were observed for ear, throat, and sinus infection by any and sectional breastfeeding duration and formula supplementation. The proportions of ear, throat, and sinus infections were everyman among those breastfed for ≥9 months, exclusively breastfed for ≥six months, or breastfed for ≥6 months without formula supplementation before six months. Although sinus infection was the only past-year infection significantly related to breast milk intensity during the first half-dozen months, P values for both ear (P = .05) and throat (P = .06) infection approached the significant level.

Table two

Prevalence of Past-Year Infections Among six-Year-Old US Children According to Breastfeeding Practices, IFPS II (2005–2007) and Y6FU (2012)

Variable	N (%)	By-Year Infections at Age 6 Years (%)
Variable	N (%)	Common cold or Upper Respiratory Tract	Ear	Pharynx	Sinus	Pneumonia or Lung	Urinary Tract
Full	1281 (100)	65.7	25.1	23.vii	15.half dozen	4.6	3.eight
Ever breastfed
No	175 (13.6)	65.7	28.0	29.7	22.3	4.six	4.half-dozen
Yep	1106 (86.4)	65.vii	24.half-dozen	22.8	14.six	4.vi	3.seven
		P = .99^a	P = .33	P = .04^b	P < .01^b	P = .98	P = .58
Duration of any breastfeeding	1106 (100)
>0 to <iii mo	311 (28.1)	65.6	28.1	26.1	twenty.nine	four.eight	iv.5
three to <6 mo	143 (12.ix)	58.0	28.0	25.2	15.4	4.9	2.8
6 to <ix mo	134 (12.one)	67.9	24.half dozen	23.1	13.four	2.ii	3.vii
≥9 mo	518 (46.ix)	67.4	21.4	xx.1	10.8	v.0	3.v
		P = .32	P = .02^b	P = .04^b	P < .01^b	P = .97	P = .55
Duration of exclusive breastfeeding	1106 (100)
>0 to <4 mo	868 (78.5)	65.iv	26.4	24.two	15.9	4.viii	3.five
4 to <6 mo	195 (17.six)	65.one	19.5	20.0	11.3	four.1	5.1
≥6 mo	43 (3.ix)	74.4	11.6	7.0	2.three	ii.three	two.3
		P = .44	P < .01^b	P < .01^b	P < .01^b	P = .41	P = .63
Formula supplementation	1106 (100)
Breastfed <6 mo with formula before 6 mo	445 (40.two)	63.eight	28.1	25.8	nineteen.1	iv.9	4.0
Breastfed ≥half-dozen mo with formula before half dozen mo	285 (25.8)	66.0	24.half-dozen	23.v	thirteen.0	5.iii	3.9
Breastfed ≥6 mo without formula earlier 6 mo	376 (34.0)	67.eight	xx.5	eighteen.6	10.four	3.7	3.2
		P = .23	P = .01^b	P = .01^b	P < .01^b	P = .42	P = .52
Chest milk intensity (% milk feedings beingness breast milk) during the outset 6 mo	1106 (100)
Low (>0 to <33.3%)	309 (27.9)	64.4	28.2	25.nine	20.vii	five.two	4.5
Medium (33.iii% to 66.six%)	120 (x.eight)	61.7	26.7	25.viii	15.0	five.0	4.2
High (>66.half dozen%)	677 (61.3)	67.1	22.vi	20.viii	eleven.7	four.3	3.iii
		P = .35	P = .05	P = .06	P < .01^b	P = .52	P = .31

Consistent with the crude analysis, multivariable analysis likewise showed that ear, throat, and sinus infections at 6 years of historic period were significantly associated with breastfeeding duration and intensity afterward controlling for the confounding factors included in the present study (Tabular array iii). Specifically, among children who were always breastfed, the adjusted odds of ear, throat, and sinus infection at 6 years of historic period were lowest among children who were breastfed for ≥ix months (versus breastfed >0 to <three months), exclusively breastfed for ≥half dozen months (versus exclusively breastfed >0 to <4 months), and breastfed for ≥six months without formula supplementation before 6 months (versus breastfed <6 months with formula supplementation before 6 months). The adjusted odds of sinus infection at half dozen years of age were as well significantly lower for children fed with high breast milk intensity during the start 6 months (aOR: 0.53 [95% CI: 0.35–0.79] versus low breast milk intensity).

Table 3

Adjusted Odds of By-Yr Infections Among 6-Yr-Onetime United states Children According to Breastfeeding Practices, IFPS Two (2005–2007) and Y6FU (2012); N = 1281

Variable	Cold or Upper Respiratory Tract Infection		Ear Infection		Pharynx Infection		Sinus Infection		Pneumonia or Lung Infection		Urinary Tract Infection
Variable	aOR^a	95% CI	aOR	95% CI	aOR	95% CI	aOR	95% CI	aOR	95% CI	aOR	95% CI
E'er breastfed (n = 1281)
No	Ref		Ref		Ref		Ref		Ref		Ref
Yep	0.93	0.65–1.32	0.94	0.65–i.36	0.74	0.51–i.07	0.70	0.47–1.06	0.89	0.40–1.99	0.78	0.34–1.78
Duration of whatsoever breastfeeding (n = 1106)
>0 to <3 mo	Ref		Ref		Ref		Ref		Ref		Ref
3 to <half-dozen mo	0.68	0.45–ane.04	1.04	0.66–1.64	1.00	0.62–1.61	0.71	0.41–1.23	0.81	0.31–2.15	0.55	0.17–1.81
vi to <9 mo	one.02	0.65–1.61	0.84	0.51–1.37	0.87	0.52–1.44	0.61	0.33–1.10	0.37	0.x–ane.39	0.73	0.23–2.37
≥9 mo	0.98	0.lxx–1.36	0.69^b	0.48–0.98^b	0.68^b	0.47–0.98^b	0.47^b	0.30–0.72^b	0.77	0.37–ane.threescore	0.54	0.23–i.25
Elapsing of exclusive breastfeeding (due north = 1106)
>0 to <4 mo	Ref		Ref		Ref		Ref		Ref		Ref
4 to <half-dozen mo	0.88	0.62–1.25	0.69	0.46–1.03	0.77	0.51–1.xvi	0.71	0.43–1.xviii	0.67	0.xxx–1.52	one.29	0.57–2.92
≥6 mo	i.32	0.64–ii.73	0.37^b	0.14–0.98^b	0.23^b	0.07–0.76^b	0.13^b	0.02–0.97^b	0.34	0.04–2.61	0.46	0.06–iii.65
Formula supplementation (n = 1106)
Breastfed <6 mo with formula earlier 6 mo	Ref		Ref		Ref		Ref		Ref		Ref
Breastfed ≥half-dozen mo with formula before half dozen mo	ane.08	0.77–i.50	0.81	0.56–one.xvi	0.86	0.59–1.24	0.65	0.42–one.01	0.92	0.44–i.ninety	0.83	0.35–1.94
Breastfed ≥6 mo without formula earlier 6 mo	1.07	0.78–1.48	0.66^b	0.46–0.94^b	0.63^b	0.44–0.92^b	0.50^b	0.32–0.78^b	0.61	0.29–1.29	0.57	0.25–1.32
Breast milk intensity (% milk feedings being breast milk) during the first 6 mo (north = 1106)
Depression (>0 to < 33.3%)	Ref		Ref		Ref		Ref		Ref		Ref
Medium (33.three% to 66.6%)	0.84	0.54–1.32	0.98	0.60–1.61	i.06	0.64–1.74	0.73	0.41–1.31	0.83	0.30–2.29	0.92	0.31–two.76
Loftier (>66.6%)	ane.03	0.75–i.41	0.77	0.54–one.08	0.73	0.51–1.03	0.53^b	0.35–0.79^b	0.62	0.31–1.26	0.51	0.23–1.xiv

Table 4 presents the proportions and adjusted odds of children having sick visits ≥2 times during the by 12 months at 6 years of age according to various breastfeeding practices during infancy. There was no human relationship between sick visits and ever breastfeeding. However, amidst children who were ever breastfed, the proportions of six-twelvemonth-olds who had ≥2 sick visits during the past 12 months were highest amongst those who were breastfed to any extent for <iii months, exclusively breastfed for <4 months, breastfed for <vi months with formula supplementation before half-dozen months, and those breastfed with low breast milk intensity during the showtime half dozen months. Like patterns were observed in the multivariable analysis.

TABLE 4

Prevalence and Adjusted Odds of half-dozen-Twelvemonth-Former US Children Having at Least 2 Sick Visits to the Medico Within the Past 12 Months According to Breastfeeding Practices, IFPS II (2005–2007) and Y6FU (2012)

Variable	Prevalence of ≥2 Sick Visits		Odds of ≥ii Sick Visits
Variable	N	Pct	aOR^a	95% CI
Total	1259	40.67
Ever breastfed
No	171	42.69	Ref
Yes	1088	40.35	0.97	0.69–ane.36
		P = .56^b
Duration of any breastfeeding
>0 to <3 mo	308	48.70	Ref
3 to <6 mo	141	35.46	0.60^c	0.39–0.92^c
vi to <nine mo	130	36.fifteen	0.63^c	0.xl–0.99^c
≥9 mo	509	37.72	0.69^c	0.50–0.94^c
		P < .01^c
Duration of exclusive breastfeeding
>0 to < 4 mo	854	43.09	Ref
4 to <6 mo	192	32.81	0.68^c	0.48–0.97^c
≥six mo	42	19.05	0.33^c	0.15–0.75^c
		P < .01^c
Formula supplementation
Breastfed <6 mo with formula before 6 mo	440	44.55	Ref
Breastfed ≥half dozen mo with formula before six mo	279	41.94	0.96	0.69–1.32
Breastfed ≥6 mo without formula before 6 mo	369	34.xv	0.seventy^c	0.51–0.95^c
		P < .01^c
Breast milk intensity (% milk feedings comprising breast milk) during the first half dozen mo
Low (>0 to < 33.3%)	307	48.53	Ref
Medium (33.3% to 66.half dozen%)	117	37.61	0.67	0.43–one.05
High (>66.half-dozen%)	664	37.05	0.67^c	0.50–0.91^c
		P < .01^c

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Our study establish that, among 6-yr-onetime children, ∼1 in 4 had an ear or throat infection, and almost 1 in vi had a sinus infection at least once in the past year. Although ear, throat, and sinus infections were non significantly associated with breastfeeding initiation, the odds of 6-yr-old children experiencing these infections in the past 12 months seemed to exist reduced by 31% to 53% if they were breastfed for ≥9 months (versus >0 to <3 months), by 63% to 87% if mothers exclusively breastfed for ≥6 months (versus >0 to <4 months), and past 34% to 50% if mothers breastfed for ≥6 months without formula supplementation before half-dozen months (versus breastfed for >0 to <6 months with formula supplementation before 6 months). Similarly, the odds of six-yr-old children having ≥2 sick visits in the by 12 months were significantly associated with duration and exclusivity of breastfeeding, the timing of supplementing breastfeeding with formula, and chest milk intensity. No association was establish between breastfeeding and colds or upper respiratory tract, pneumonia or lung, or urinary tract infections.

The ear, throat, and paranasal sinus are all common sites of infection amid children. Otitis media accounts for at least 24 one thousand thousand clinic visits each year in the U.s. and is the nearly mutual condition for which antibiotics are prescribed.¹⁸ ^, ^nineteen A previous meta-assay of 266 studies found that among children of all ages who present with sore throat, the pooled prevalence of grouping A streptococcus was 37% and the prevalence of grouping A streptococcus wagon amidst well children with no signs or symptoms of pharyngitis was 12%.²⁰ Although the exact prevalence and incidence of sinus infection are unknown, it is estimated that up to one billion cases of astute sinusitis occur in the United States each twelvemonth, with $two.two billion spent on nonprescription and prescription medications for viral and bacterial sinusitis.²¹

Homo milk contains a wealth of immunologic factors that fight against infections during infancy. However, the mechanisms past which human milk confers protective furnishings that last beyond infancy and afterwards breastfeeding ends are unclear. It has been speculated that immunologic factors in breast milk influence the development of the infant's immune system such that they influence the pathogenesis of illness afterward in life. For example, the thymus is a key organ in the immune system, responsible for the proper development of T lymphocytes. Using an ultrasound technique to measure out thymic index size, Hasselbalch et al²² plant that, at iv months of historic period, infants who were exclusively breastfed had significantly larger thymus glands than those who were partially breastfed or formula-fed only. Jeppesen et al²³ later published a study that not merely substantiated their previous findings regarding increased thymus size with breastfeeding, but it also constitute a correlation between breastfeeding and CD8+ T cells. Alho et al²⁴ found that one of the major risk factors for otitis media was the being of a previous episode of otitis media, and the odds were even stronger (odds ratio: 3.74 [CI: 3.40–4.10]) if the previous episode had occurred within the preceding 3 months. This finding suggests that breastfeeding's protective effects on ear infections later in life could be as well mediated through lower prevalence of otitis media during infancy.

At that place are several strengths of the present study. First, data were gathered from a detailed longitudinal study on baby feeding practices in the U.s., and potential reporting bias for the feeding variables was minimized past a brusque 7-day retrospective recall at near-monthly intervals throughout the showtime twelvemonth. Furthermore, the potentially confounding effects of other variables were limited by controlling for a wide range of variables in the multivariable analysis. In improver, various indicators of breastfeeding practices during infancy were explored, and we captured multiple aspects of babe feeding exposures, including initiation, duration, intensity, and exclusivity of breastfeeding, as well as the timing of supplementing breastfeeding with formula.

Yet, our results are subject to some limitations. Get-go, because black and Hispanic mothers were underrepresented in this study, our results may not be applicable to the entire U.s. population. 2nd, infections were self-reported past mothers who were not specifically instructed to report infectious illnesses that must be established by doctor diagnoses during an office or clinic visit. Even if the diagnoses were established in this manner, there is great variability with regard to "certainty" of diagnoses, depending on the knowledge and training of the examining physician. For instance, the diagnosis of sinus infections (sinusitis or inflammation of the paranasal sinuses) is extremely difficult clinically to distinguish from common rhinitis (inflammation of the nasal passages) without resorting to a sinus radiograph. Because it is unlikely that the misclassification of infections depended on early breastfeeding practices given the longitudinal pattern of this written report (nondifferential misclassification), the reporting errors well-nigh likely bias the results toward the null.²⁵

Conclusions

This national prospective study of long-term associations of breastfeeding and infections amongst half-dozen-twelvemonth-olds in the The states suggests that breastfeeding may protect against ear, throat, and sinus infections well beyond infancy. Given the potentially harmful and costly effects of these infections, improving breastfeeding practices amidst US mothers could prove beneficial. Breastfeeding mothers demand to be encouraged and supported in making their decisions to initiate breastfeeding and to maintain sectional breastfeeding for the showtime 6 months as recommended by the American Academy of Pediatrics,^three and to go on breastfeeding for at to the lowest degree ane year and as long thereafter as they want. With optimal breastfeeding practices, the incidence of ear, throat, and sinus infections in later babyhood has the potential to be reduced, thereby improving the health and well-existence of many Usa children.

Acknowledgments

The authors thank the mothers/other caregivers, children, and families who participated in this longitudinal study.

Glossary

aOR	adjusted odds ratio
CI	confidence interval

Footnotes

Dr Li conducted the analysis and drafted the manuscript. All authors had technical input for the analytic design and contributed to and canonical the last manuscript.

The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Affliction Control and Prevention.

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

FUNDING: This study was funded by the The states Nutrient and Drug Assistants, Centers for Disease Control and Prevention, Office on Women'south Health, National Institutes of Health, and Maternal and Kid Health Bureau in the US Department of Health and Human Services.

POTENTIAL CONFLICTS OF INTEREST: The authors have no conflicts of involvement relevant to this commodity to disclose.

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Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4258846/