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Morbidity in breast-fed and artificially fed infants
May 1977
726
TheJournalofPEDIATRICS
Morbidity in breast-fed and artificially fed infants One-half of the health): newborn infants at a rural medical center were initially breast fec~ the proportion declined to 4% by one year of age. Breast-feeding was associated with significant!y less illness during the first year, especially if continued beyond 41/2 months of age. Breast~feeding was associated with a higher level o f parental education and, by inference, higher socioeconomic status. The health advantage of breast-feeding was still evident after controlling for parental educational status. In better educated families the difference in significant illness between infants who were artificially f e d and those who were breast f e d for prolonged periods of time was two- to threefold.
Allan S. Cunningham, M.D., Cooperstown, N. Y.
IN RECENT YEARS cogent immunologic arguments favoring breast-feeding have been advanced.' :~They have provided theoretical support for older morbiditymortality studies which showed health advantages for breast-fed infants? ~ In spite of this, there is considerable skepticism about the advantages of breast-feeding in a modern industrial society. One small study in middle class families showed no difference in the amount of illness between breast- and bottle-fed babies? Janeway,'" although encouraging breast-feeding in all cultures, suggested that the advantages in the United States were largely " . . . subtle and psychological." Clearly, more recent information regarding the impact of feeding on the health of infants in industrial nations is needed. The following study provides such information for infants seen at a rural medical center in upstate New York.
MATERIAL
AND METHODS
The medical records of all infants born at the Mary Imogene Bassett Hospital during a one-year period (February, 1974, through January, 1975) were reviewed. There were 357 live births. Thirty-one infants who weighed less than 2,500 gm at birth or who had serious problems during the newborn period were excluded from further
From the Department oJ" Pediatrics, The Mary Imogene Bassett Hospital Supported by The Stephen C. Clark Research Fund. Reprint address: The Mary lmogene Bassett Hospital, Cooperstown, N Y 13326.
Vol. 90, No. 5, pp. 726-729
consideration. In the 326 infants remaining, the following items were tabulated from the medical records and birth certificates: birth weight, sex, mode of delivery, Apgar score, mother's age, number of living children, the educational level of each parent, and feeding mode at the time of discharge from the nursery. Two hundred fifty-three infants were seen regularly at the pediatric clinic during the first year of life. The following items were tabulated from entries in the medical record during the first year: duration of breast-feeding, number of outpatient visits for well-child examinations and common complaints (primarily feeding problems, rhinitis, and rashes), and any episode of significant illness. The designation of significant illness was limited to episodes of otitis media, lower respiratory disease (croup, bronchitis, pneumonia, o r any illness accompanied by wheezing), significant vomiting or diarrhea, and any illness requiring hospital admission, excluding trauma or surgery for congenital abnormalities. Duration of breast-feeding was defined as the age at which the last feeding of breast milk was given. An infant was considered breast fed even if substantial amounts of solid food or formula feeding had supplemented breastfeeding. Prolonged breast-feeding was defined as breastfeeding beyond 4% months. Limited breast-feeding was defined as complete weaning to artificial feedings prior to that time. In morbidity and social comparisons (Tables If, IV, and V), infants who had been completely weaned prior to 6 weeks of age were grouped with bottle-fed infants. Indeed, most of these infants received no breast
Volume 90 Number 5
milk past the third week of life. Bottle-fed infants generally received proprietary formula for at least three months before they were given whole cow milk. Breast-feeding was prolonged in 64 infants and limited in 42 infants. There were 147 artificially fed infants; 123 were lotally bottle fed and 24 infants were briefly breast fed, but were weaned to the bottle before 6 weeks of age. To achieve fair morbidity comparisons between bottlefed and breast-fed infants, the aggregate n u m b e r of patient-weeks by feeding mode was calculated. There was a total of 1L156 patient-weeks (253 patients x 52 weeks). Strictly bottle-fed infants accounted for an aggregate of 6,396 patient-weeks (123 patients x 52 weeks). Infants initially breast fed accounted for 2,947 patient-weeks on breast-feeding plus 3,813 patient-weeks receiving only artificial feeds. Standard statistical methods were used to evaluate the data, including the t test and the X" test with the Yates correction for continuity. RESULTS At the time of discharge from the newborn nursery, 164 infants were being breast fed and 162 were receiving only proprietary formula. The groups were comparable with respect to average birth weight, sex distribution, Apgar score, and mode of delivery. In Table I the decline in the proportion of infants being breast fed during the first year of life is summarized. Social factors and feeding mode. Breast-feeding was significantly associated with educational advancement in both parents and with increased maternal age. There was a tendency for prolonged breast-feeding to be associated with smaller family size, but the difference was not statistically significant. Pertinent data are summarized in Table ll. Morbidity and feeding mode. Episodes of significant illness were u n c o m m o n in breast-fed infants. Infants being breast fed accounted for an estimated 22% of all patient-weeks, but for only 9% of all significant illness episodes and 3% of all hospital admissions (one partially breast-fed infant was hospitalized at 4 months of age for what proved to be roseola). Life-threatening illness did not occur in any breast-fed infant. Five bottle-fed infants developed p n e u m o n i a ; another was severely ill with Hemophilus influenzae meningitis. One previously healthy full-term newborn infant was unexpectedly found dead in his crib at age 2 weeks; postmortem examination was consistent with sudden infant death syndrome. These data are summarized in Table III. The age when significant illness occurred, regardless of
Morbidity in breast- and bottle-fed iafants
727
Table I. Decline in breast-feeding during the first year of life
Age
No. still breast fed/total
%
Nursery ~ 6 wk ~ 3 mo _>4 89 _> 6 mo ~9mo 1 yr
164/326" 106/253 84/253 64/253 49/253 33/253 10/253
50 42 33 25 19 13 4
*Thirty-fourinitiallybreast-fed infants and 39 bottle-fed infants were not routinely followed during the first year.
Table 1I. Social determinants of feeding mode
Mean educational level (yr) Fathert Mothers Mean maternal agew Mean No. of living children
Breast Prolonged I Limited 15.5 14.6 26.6 0.9
13.2 13.2 25.2 1.2
art~c~l* 12.2 12.1 24.7 1.0
*Includes infants breast fed less than 6 weeks. tBy t test, p < 0.001 for prolonged-limited and prolonged-artificial comparisons; p < 0.05 for limited-artificialcomparison. Sp < 0.001 for all three feeding-groupcomparisons. w < 0.01 for prolonged-artificialcomparison;other differenceswere not significant.
Table II1, Significant episodes of illness according to feeding mode at time of onset of illness*
Illness Otitis media Acute lower respiratory illness Significant vomiting or diarrhea Hospital admissions$ Total episodes of illness$
Breastt (2,947 patientweeks)
ArtificiaR (10,209 patientweeks)
X~ test
3.4 (10) 0.34 (1)
6.3 (64) 5.5 (56)
p < 0.10 p < 0.001
2.0
(6)
4.9 (50)
p < 0.05
0.34 (1)
2.9 (30)
p < 0.02
5.8 (17)
16.8 (172)
p < 0.001
*Does not include one apparent crib death in a 2-week old, bottle-fed infant. tEpisodes per 1,000patient-weeks(number of episodes). $Includes hospital admissionsfor H. influenzae meningitis,pyloric stenosis, urticaria, or unexplained fever, all in bottle-fed infants; the only breast-fed infant hospitalized proved to have roseola.
728
Cunningham
The Journal of Pediatrics May 1977
IV. Significant episodes of illness, regardless of feeding mode, at onset of illness
Table
Breast* (106 patients) Months of life
1-2 3-4 5-6 7-8 9-10 11-12 First year:~
Prolonged (64)
Limited (42)
Artificial* (147 patientsff
0 (0) 1.6 (1) 6.2 (4) 17.2(11) 10.9 (7) 6.2 (4) 42.2 (27)
4.8 (2) 11.9 (5) 19.0 (8) 7.1 (3) 16.7 (7) 16.7 (7) 76.2 (32)
8.8 (13) 12.9 (19) 19.0 (8) 16.3 (24) 11.6 (17) 19.7 (29) 88.4 (130)
"Episodesper 100 patients (number of episodes). tlncludes infants breast fed less than 6 weeks. :]:ByX~test; p < 0.0l. Table V. First year episodes of illness in families with high and low educational levels Breast* Educational level Prolonged Limit~d
Father >12 years --<12 years Mother >12 years _<12 years
A rtificial~r
X2 test
41 (20/49)* 65 (11/17) 108 (41/38) p < 0.001 47 (7/15) 84 (21/25) 82 (89/109) NS 39 (17/44) 42 (8/19) 75 (30/40) 50 (10/20) 104 (24/23) 93 (100/107)
p < 0.05 NS
NS = n o t significant. '~Episodesper 100 patients (number of episodes/numberof patients). tlncludes infants breast-fedless than 6 weeks. the feeding mode at onset, was tabulated for each of the three feeding groups. The data are summarized in Table IV. The development of significant illness was delayed in infants who were breast fed for prolonged periods of time; peak incidence appeared to occur during weaning. The first year incidence of illness in infants given prolonged breast-feeding was about half that in bottle-fed infants or in those given limited breast-feeding. In part this was due to the tendency for some bottle-fed infants to have repeated episodes of illness. However, the proportion of infants suffering any significant episode of illness increased as the extent of breast-feeding declined. Thirtyfour percent (22/64) of infants given prolonged breastfeeding had one or more episodes during the first year. The figures for limited breast-feeding and bottle-fed infants were 48% (20/42) and 53% (78/147), respectively. These differences were significant (p < 0.05). Infants given prolonged breast-feeding were seen for other common complaints (e.g., "colic," rhinitis, rashes) at an average of 1.5 clinic visits during the year. The figures
for those given limited breast-feeding and for infants given only artificial feedings were 2.3 and 2.1, respectively. These differences were significant (p < 0.01). All three groups were seen, on the average, at five visits for well-child examinations. Since lower morbidity in breast-fed infants could be the result of associated factors such as higher socioeconomic status, feeding groups were subdivided according to each parent's educational level and the incidence of illness within the subgroups was ascertained. These data are summarized in Table V. The health advantages of breastfeeding were independent of educational levels and, by inference, of the family's socioeconomic status. When bottle-fed infants and those fed breast milk for prolonged time periods were compared within the group of better educated families, the morbidity difference favoring the latter was two- to threefold. There was no evidence suggesting underlying chronic illness in individuals in any feeding group which would have biased morbidity data unfavorably. Growth and development in each group appeared to be comparable. Strictly bottle-fed infants were slightly heavier at 6 months of age, on the average, than infants receiving prolonged breast-feeding (7,601 gm and 7,453 gm, respectively) and included a somewhat greater proportion above the ninetieth weight percentile after 41/2 months of age (17% and 8%, respectively). On the other hand, a slightly smaller proportion of bottle-fed infants fell below the tenth percentile (10% and 14%, respectively). These differences were not statistically significant. DISCUSSION Some problems should be anticipated in attempting to study morbidity and mortality in breast-fed infants. Existing studies suggest that the most striking differences will be evident among the p o o r , ' - " and that the differences will be greatest when prolonged, exclusive breastfeeding is compared with exclusive artificial feeding? .~. " Breast-feeding has become a middle-class phenomenon in industrial nations." ':~ In 1966, fewer than one mother in three even initiated breast-feeding in the United States." Although recent estimates suggest an increase in breastfeeding, even now less than 5% of infants in the United States receive any breast milk after 6 months? ~ Furthermore, most breast-fed infants now receive supplements early. All of these trends serve to reduce the number of infants available for a comparison likely to show any health advantages of breast-feeding. General feeding trends are reflected in the group of infants studied here, inasmuch as breast-feeding was practiced more frequently in better educated families and tended to be limited in extent and duration. Nevertheless,
Volume 90 Number 5
it was possible to show that in a small town, rural setting where regular health surveillance is available for all socioeconomic groups, breast-feeding is associated with distinct health advantages. The advantages are demonstrable in the context of good hygiene, intelligent parental care, and readily available medical services, especially when breast-feeding is prolonged. The author is indebted to Dr. Joe H. Cannon and the pediatric staff for suggestions regarding the manuscript and to Mrs. Peg Blumenstock for its preparation. REFERENCES
1. Goldman AS, and Smith CW: Host resistance factors in human milk, J PEDIATR82:1082, 1973. 2. Lead article: Br Med J 1:1167, 1976. 3. Gerrard JW: Breast-feeding: Second thoughts, Pediatrics 54:757, 1974. 4. Woodbury RM: The relation between breast and artificial feeding and infant mortality, Am J Hyg 2:668, 1922. 5. Grulee CG, Sanford HN, and Herron PH: Breast and artificial feeding. Influence on morbidity and mortality of twenty thousand infants, JAMA 103:735, 1934.
Morbidity in breast- and bottle-fed infants
729
6. Grulee CG, Sanford HN, and Schwartz H: Breast and artificially fed infants. A study of the age incidence in the morbidity and mortality in twenty thousand cases, JAMA 104:1986, 1935. 7. Robinson M: Infant morbidity and mortality: A study of 3266 infants, Lancet 1:788, 1951. 8. Stewart A, and Westropp C: Breast-feeding in The Oxford Child Health Survey. Part II. Comparison of bottle- and breast-fed babies, Br Med J 2:305, 1953. 9. Adebonjo FO: Artificial vs breast feeding: Relation to infant health in a middle class American community, Clin Pediatr 11:25, 1972. 10. Janeway CA: The mammary gland-an area of pediatric neglect, The R. Cannon Eley Lecture, Boston, Mass, September 11, 1974. 11. Plank SJ, and Milanesi ML: Infant feeding and infant mortality in rural Chile, Bull WHO 48:203, 1973. 12. Fomon SJ: What are infants fed in the United States? Pediatrics 56:350, 1975. 13. Sloper K, McKean L, and Baum JD: Factors influencing breast feeding, Arch Dis Child 50:165, 1975. 14. Meyer HF: Breast feeding in the United States: Report of a 1966 national survey with comparable 1946 and 1956 data, Clin Pediatr 7:708, 1968.
726
TheJournalofPEDIATRICS
Morbidity in breast-fed and artificially fed infants One-half of the health): newborn infants at a rural medical center were initially breast fec~ the proportion declined to 4% by one year of age. Breast-feeding was associated with significant!y less illness during the first year, especially if continued beyond 41/2 months of age. Breast~feeding was associated with a higher level o f parental education and, by inference, higher socioeconomic status. The health advantage of breast-feeding was still evident after controlling for parental educational status. In better educated families the difference in significant illness between infants who were artificially f e d and those who were breast f e d for prolonged periods of time was two- to threefold.
Allan S. Cunningham, M.D., Cooperstown, N. Y.
IN RECENT YEARS cogent immunologic arguments favoring breast-feeding have been advanced.' :~They have provided theoretical support for older morbiditymortality studies which showed health advantages for breast-fed infants? ~ In spite of this, there is considerable skepticism about the advantages of breast-feeding in a modern industrial society. One small study in middle class families showed no difference in the amount of illness between breast- and bottle-fed babies? Janeway,'" although encouraging breast-feeding in all cultures, suggested that the advantages in the United States were largely " . . . subtle and psychological." Clearly, more recent information regarding the impact of feeding on the health of infants in industrial nations is needed. The following study provides such information for infants seen at a rural medical center in upstate New York.
MATERIAL
AND METHODS
The medical records of all infants born at the Mary Imogene Bassett Hospital during a one-year period (February, 1974, through January, 1975) were reviewed. There were 357 live births. Thirty-one infants who weighed less than 2,500 gm at birth or who had serious problems during the newborn period were excluded from further
From the Department oJ" Pediatrics, The Mary Imogene Bassett Hospital Supported by The Stephen C. Clark Research Fund. Reprint address: The Mary lmogene Bassett Hospital, Cooperstown, N Y 13326.
Vol. 90, No. 5, pp. 726-729
consideration. In the 326 infants remaining, the following items were tabulated from the medical records and birth certificates: birth weight, sex, mode of delivery, Apgar score, mother's age, number of living children, the educational level of each parent, and feeding mode at the time of discharge from the nursery. Two hundred fifty-three infants were seen regularly at the pediatric clinic during the first year of life. The following items were tabulated from entries in the medical record during the first year: duration of breast-feeding, number of outpatient visits for well-child examinations and common complaints (primarily feeding problems, rhinitis, and rashes), and any episode of significant illness. The designation of significant illness was limited to episodes of otitis media, lower respiratory disease (croup, bronchitis, pneumonia, o r any illness accompanied by wheezing), significant vomiting or diarrhea, and any illness requiring hospital admission, excluding trauma or surgery for congenital abnormalities. Duration of breast-feeding was defined as the age at which the last feeding of breast milk was given. An infant was considered breast fed even if substantial amounts of solid food or formula feeding had supplemented breastfeeding. Prolonged breast-feeding was defined as breastfeeding beyond 4% months. Limited breast-feeding was defined as complete weaning to artificial feedings prior to that time. In morbidity and social comparisons (Tables If, IV, and V), infants who had been completely weaned prior to 6 weeks of age were grouped with bottle-fed infants. Indeed, most of these infants received no breast
Volume 90 Number 5
milk past the third week of life. Bottle-fed infants generally received proprietary formula for at least three months before they were given whole cow milk. Breast-feeding was prolonged in 64 infants and limited in 42 infants. There were 147 artificially fed infants; 123 were lotally bottle fed and 24 infants were briefly breast fed, but were weaned to the bottle before 6 weeks of age. To achieve fair morbidity comparisons between bottlefed and breast-fed infants, the aggregate n u m b e r of patient-weeks by feeding mode was calculated. There was a total of 1L156 patient-weeks (253 patients x 52 weeks). Strictly bottle-fed infants accounted for an aggregate of 6,396 patient-weeks (123 patients x 52 weeks). Infants initially breast fed accounted for 2,947 patient-weeks on breast-feeding plus 3,813 patient-weeks receiving only artificial feeds. Standard statistical methods were used to evaluate the data, including the t test and the X" test with the Yates correction for continuity. RESULTS At the time of discharge from the newborn nursery, 164 infants were being breast fed and 162 were receiving only proprietary formula. The groups were comparable with respect to average birth weight, sex distribution, Apgar score, and mode of delivery. In Table I the decline in the proportion of infants being breast fed during the first year of life is summarized. Social factors and feeding mode. Breast-feeding was significantly associated with educational advancement in both parents and with increased maternal age. There was a tendency for prolonged breast-feeding to be associated with smaller family size, but the difference was not statistically significant. Pertinent data are summarized in Table ll. Morbidity and feeding mode. Episodes of significant illness were u n c o m m o n in breast-fed infants. Infants being breast fed accounted for an estimated 22% of all patient-weeks, but for only 9% of all significant illness episodes and 3% of all hospital admissions (one partially breast-fed infant was hospitalized at 4 months of age for what proved to be roseola). Life-threatening illness did not occur in any breast-fed infant. Five bottle-fed infants developed p n e u m o n i a ; another was severely ill with Hemophilus influenzae meningitis. One previously healthy full-term newborn infant was unexpectedly found dead in his crib at age 2 weeks; postmortem examination was consistent with sudden infant death syndrome. These data are summarized in Table III. The age when significant illness occurred, regardless of
Morbidity in breast- and bottle-fed iafants
727
Table I. Decline in breast-feeding during the first year of life
Age
No. still breast fed/total
%
Nursery ~ 6 wk ~ 3 mo _>4 89 _> 6 mo ~9mo 1 yr
164/326" 106/253 84/253 64/253 49/253 33/253 10/253
50 42 33 25 19 13 4
*Thirty-fourinitiallybreast-fed infants and 39 bottle-fed infants were not routinely followed during the first year.
Table 1I. Social determinants of feeding mode
Mean educational level (yr) Fathert Mothers Mean maternal agew Mean No. of living children
Breast Prolonged I Limited 15.5 14.6 26.6 0.9
13.2 13.2 25.2 1.2
art~c~l* 12.2 12.1 24.7 1.0
*Includes infants breast fed less than 6 weeks. tBy t test, p < 0.001 for prolonged-limited and prolonged-artificial comparisons; p < 0.05 for limited-artificialcomparison. Sp < 0.001 for all three feeding-groupcomparisons. w < 0.01 for prolonged-artificialcomparison;other differenceswere not significant.
Table II1, Significant episodes of illness according to feeding mode at time of onset of illness*
Illness Otitis media Acute lower respiratory illness Significant vomiting or diarrhea Hospital admissions$ Total episodes of illness$
Breastt (2,947 patientweeks)
ArtificiaR (10,209 patientweeks)
X~ test
3.4 (10) 0.34 (1)
6.3 (64) 5.5 (56)
p < 0.10 p < 0.001
2.0
(6)
4.9 (50)
p < 0.05
0.34 (1)
2.9 (30)
p < 0.02
5.8 (17)
16.8 (172)
p < 0.001
*Does not include one apparent crib death in a 2-week old, bottle-fed infant. tEpisodes per 1,000patient-weeks(number of episodes). $Includes hospital admissionsfor H. influenzae meningitis,pyloric stenosis, urticaria, or unexplained fever, all in bottle-fed infants; the only breast-fed infant hospitalized proved to have roseola.
728
Cunningham
The Journal of Pediatrics May 1977
IV. Significant episodes of illness, regardless of feeding mode, at onset of illness
Table
Breast* (106 patients) Months of life
1-2 3-4 5-6 7-8 9-10 11-12 First year:~
Prolonged (64)
Limited (42)
Artificial* (147 patientsff
0 (0) 1.6 (1) 6.2 (4) 17.2(11) 10.9 (7) 6.2 (4) 42.2 (27)
4.8 (2) 11.9 (5) 19.0 (8) 7.1 (3) 16.7 (7) 16.7 (7) 76.2 (32)
8.8 (13) 12.9 (19) 19.0 (8) 16.3 (24) 11.6 (17) 19.7 (29) 88.4 (130)
"Episodesper 100 patients (number of episodes). tlncludes infants breast fed less than 6 weeks. :]:ByX~test; p < 0.0l. Table V. First year episodes of illness in families with high and low educational levels Breast* Educational level Prolonged Limit~d
Father >12 years --<12 years Mother >12 years _<12 years
A rtificial~r
X2 test
41 (20/49)* 65 (11/17) 108 (41/38) p < 0.001 47 (7/15) 84 (21/25) 82 (89/109) NS 39 (17/44) 42 (8/19) 75 (30/40) 50 (10/20) 104 (24/23) 93 (100/107)
p < 0.05 NS
NS = n o t significant. '~Episodesper 100 patients (number of episodes/numberof patients). tlncludes infants breast-fedless than 6 weeks. the feeding mode at onset, was tabulated for each of the three feeding groups. The data are summarized in Table IV. The development of significant illness was delayed in infants who were breast fed for prolonged periods of time; peak incidence appeared to occur during weaning. The first year incidence of illness in infants given prolonged breast-feeding was about half that in bottle-fed infants or in those given limited breast-feeding. In part this was due to the tendency for some bottle-fed infants to have repeated episodes of illness. However, the proportion of infants suffering any significant episode of illness increased as the extent of breast-feeding declined. Thirtyfour percent (22/64) of infants given prolonged breastfeeding had one or more episodes during the first year. The figures for limited breast-feeding and bottle-fed infants were 48% (20/42) and 53% (78/147), respectively. These differences were significant (p < 0.05). Infants given prolonged breast-feeding were seen for other common complaints (e.g., "colic," rhinitis, rashes) at an average of 1.5 clinic visits during the year. The figures
for those given limited breast-feeding and for infants given only artificial feedings were 2.3 and 2.1, respectively. These differences were significant (p < 0.01). All three groups were seen, on the average, at five visits for well-child examinations. Since lower morbidity in breast-fed infants could be the result of associated factors such as higher socioeconomic status, feeding groups were subdivided according to each parent's educational level and the incidence of illness within the subgroups was ascertained. These data are summarized in Table V. The health advantages of breastfeeding were independent of educational levels and, by inference, of the family's socioeconomic status. When bottle-fed infants and those fed breast milk for prolonged time periods were compared within the group of better educated families, the morbidity difference favoring the latter was two- to threefold. There was no evidence suggesting underlying chronic illness in individuals in any feeding group which would have biased morbidity data unfavorably. Growth and development in each group appeared to be comparable. Strictly bottle-fed infants were slightly heavier at 6 months of age, on the average, than infants receiving prolonged breast-feeding (7,601 gm and 7,453 gm, respectively) and included a somewhat greater proportion above the ninetieth weight percentile after 41/2 months of age (17% and 8%, respectively). On the other hand, a slightly smaller proportion of bottle-fed infants fell below the tenth percentile (10% and 14%, respectively). These differences were not statistically significant. DISCUSSION Some problems should be anticipated in attempting to study morbidity and mortality in breast-fed infants. Existing studies suggest that the most striking differences will be evident among the p o o r , ' - " and that the differences will be greatest when prolonged, exclusive breastfeeding is compared with exclusive artificial feeding? .~. " Breast-feeding has become a middle-class phenomenon in industrial nations." ':~ In 1966, fewer than one mother in three even initiated breast-feeding in the United States." Although recent estimates suggest an increase in breastfeeding, even now less than 5% of infants in the United States receive any breast milk after 6 months? ~ Furthermore, most breast-fed infants now receive supplements early. All of these trends serve to reduce the number of infants available for a comparison likely to show any health advantages of breast-feeding. General feeding trends are reflected in the group of infants studied here, inasmuch as breast-feeding was practiced more frequently in better educated families and tended to be limited in extent and duration. Nevertheless,
Volume 90 Number 5
it was possible to show that in a small town, rural setting where regular health surveillance is available for all socioeconomic groups, breast-feeding is associated with distinct health advantages. The advantages are demonstrable in the context of good hygiene, intelligent parental care, and readily available medical services, especially when breast-feeding is prolonged. The author is indebted to Dr. Joe H. Cannon and the pediatric staff for suggestions regarding the manuscript and to Mrs. Peg Blumenstock for its preparation. REFERENCES
1. Goldman AS, and Smith CW: Host resistance factors in human milk, J PEDIATR82:1082, 1973. 2. Lead article: Br Med J 1:1167, 1976. 3. Gerrard JW: Breast-feeding: Second thoughts, Pediatrics 54:757, 1974. 4. Woodbury RM: The relation between breast and artificial feeding and infant mortality, Am J Hyg 2:668, 1922. 5. Grulee CG, Sanford HN, and Herron PH: Breast and artificial feeding. Influence on morbidity and mortality of twenty thousand infants, JAMA 103:735, 1934.
Morbidity in breast- and bottle-fed infants
729
6. Grulee CG, Sanford HN, and Schwartz H: Breast and artificially fed infants. A study of the age incidence in the morbidity and mortality in twenty thousand cases, JAMA 104:1986, 1935. 7. Robinson M: Infant morbidity and mortality: A study of 3266 infants, Lancet 1:788, 1951. 8. Stewart A, and Westropp C: Breast-feeding in The Oxford Child Health Survey. Part II. Comparison of bottle- and breast-fed babies, Br Med J 2:305, 1953. 9. Adebonjo FO: Artificial vs breast feeding: Relation to infant health in a middle class American community, Clin Pediatr 11:25, 1972. 10. Janeway CA: The mammary gland-an area of pediatric neglect, The R. Cannon Eley Lecture, Boston, Mass, September 11, 1974. 11. Plank SJ, and Milanesi ML: Infant feeding and infant mortality in rural Chile, Bull WHO 48:203, 1973. 12. Fomon SJ: What are infants fed in the United States? Pediatrics 56:350, 1975. 13. Sloper K, McKean L, and Baum JD: Factors influencing breast feeding, Arch Dis Child 50:165, 1975. 14. Meyer HF: Breast feeding in the United States: Report of a 1966 national survey with comparable 1946 and 1956 data, Clin Pediatr 7:708, 1968.