- Email: [email protected]
Illnesses within the first year of life
I L L N E S S E S W I T H I N T I l E F I R S T Y E A R OF I~IFE ~IILDIIE.D ~'k. NORVAL, MI.I)., AND I{OGER l]. J . KENNEDY, M.I). ]~OC HESTER, MINN.
L T I I O U G H the morbidity rate is said to be highest in the first year of life, few artie]es in the literature supply definite information about illnesses in lhis period. The purpose of this i)ape~" is to present data obtained in a study o[ illnesses that occurred among 417 infants during their fb'st year of life. Illness was interpreted as a continuous period of " i n f e c t i o n " i'egardless of eomplieation. This definition ruled out sueh conditions as infantile eolie, injuries, operations, the more simple dermatologie conditions, and congenital defects such as clubfeet. If one condition was reported as the p r i m a r y cause and was assoeiated with other conditions, only the p r i m a r y cause was tabulate& If there was more than one cause of illness, the disease most specifically associated with the period of sickness was preferred over a minor condition which preceded or accompanied it. Records obtained in this manner were of the incidence of attacks I'ather than of illnesses in the sense of chronic illhealth.
A
The infants in this series were born of residents of Rochester, Minn., during 1944 through 194:6. Owing to the uniquely coordinated program of medical care for children in this city, most of the infants are seen at a well child clinic each month during their first year of life. For their more serious illnesses most of these ehihlren are attended by a pediatrician. To be assured that the i n f o f mation concerning the illnesses was collected from the infants' mothers at frequent intervals, only those infants were selected who had attended the Well Child C.1inie at least nine times d u r i n g their firsl year of life. At each of these conferences with the mother, the physician inquired about any illnesses that the child might have had since his last visit, and recorded the diagnosis, approximate date, and whether a physician attended the child during the illness. As a cheek that all illnesses were reported, the pediatricians' reeords on these children weI'e reviewed and a record of any additional illnesses was inserled. This selection of infants does eliminate the few children who were chronically ill and needed prolonged care by a pediatrician, or who might have died before the end of the first year, but we have included any illness that was o~:served by the mother, no matter how mild. Among this group of 417 infants there were recorded 679 illnesses, which wm'e distributed equally between the boys and tile girls. This is not in agreenlent with the illness study by Collins, ~ who found the ill,less rates for ~nales to be eonsistently greater than those for females except in the age period ] to 2 months. Data for his study were obtained from five different illness studies conducted by pe~'iodic canvasses of families within the past twenty-five years. F~'orn the Depal'lrnent of Pediatrics, Mayo Foundation and Mayo Clinic.
43
44
THE
JOURNAL
OF P E D I A T R I C S
I n eaeh survey the :families were visited at intervals of two to fOUl' months, and a record was made of any illness of the infants under observation by month of age up to twelve months. Falk and his assoeiates ~ had f o u n d in a public health survey that illnesses in the first fifteen years of life were equally distributed between the two sexes. Illness was defined by Falk as " a n y disorder that wholly or partially disabled an individual for one or more days or as an experience for which mediea] service of any kind is received. Any condition, symptom or disorder {or which drugs costing fifty cents or more are purchased is considered an illness." 2.6 ~4 --
Z0-q
t6 --
tz
l~e~?~atovy
6
..o.-,
4
0
!
Ga stt~o-intestinal
2
Birth
t
2.
3
5
6
7
I
I
5
9
/
I i0
ll
A~e -months J~'ig. 1 . - - T h e
i n e i d e n e e of i l l n e s s i n r e l a t i o n
to t h e a g e of t h e i n f a n t .
Tile incidence of illness for this group of infants was 1.63 per infant for tile age period studied. This is a higher incidenee of illness than was found by l%lk and his associates, Collins, or Sydenstrieker, a but lower than Stevenson 4 reported. Falk found that the incidence rate of illness during' the first year of life varied between 1.29 and 1.39 per infant depending on the income level of the families. Collins f o u n d an illness rate of 1.45 per person for infants less than 1 year of age. I n the Hagerstown morbidity study, a the rate was 1.59 per person for ehildren less than 5 years of age. Stevenson found among 263 infants in Bost(m, who were carefully followed in a longitudinal study of child health and development, that the average number of infeetions per infant varied from 1.79 to 2.43 per year aceording to the method of feeding. Some variations in the reported ineidence rate of illness can be aeeounted for by different definitions of illness, the variety of income groups surveyed, the geographic location of the subjects, and the ages of the individuals observed.
NORVAL AND K E N N E D Y :
ILLNESSES ~vVITHIN FIRST YEAR OF LIF E
45
Of the 417 infants in this series, 22.8 per cent were reported as not being ill during their first year of life, 28.5 per cent had one illness, 26.2 per cent had two illnesses, and 22.5 per cent had three or more. Among nearly 40,000 persons of all ages, Collins found that 48 per cent did not suffer from illness during a year, 32 per cent were ill once, 13 per cent twice, and 7 per cent three or more times. Similar figures were obtained by Falk and his associates from a study of members of 9,000 white families in seventeen states. The distribution of illnesses according to the age of the infant is shown in Fig. 1. There is a steady rise in the nmnber of illnesses from all causes as the infants approach their first birthday, as well as in the illnesses due to respiratory and gastrointestinal disease. The illnesses during the last six months of the first year are approximately three times the number during the first six months of life; this increase is of the same order among the respiratory and the g'astrointestinal diseases. Grulee and his associates 5, G investigated the morbidity from infections among 20,000 artificially-fed and breast-fed infants who were followed for as long as nine months by Chicago's I n f a n t Welfare Society during 1924 to 1929. They found a rise in the illness rate each month until the fifth month with all types of infant feeding; the rate then decreased in the breast-fed and partially breast-fed groups but in the artificially-fed group the rise continued through the ninth month. Collins found that illnesses from all causes start with a high rate for the first month of life and drop to the lowest rate in the second month, followed by a gradual increase to a level of about 1.5 illnesses per infant throughout the last half of the first year of life. The digestive diseases had a high rate in the first month of life; then the rate fell rapidly and remained quite stable throughout the first year, while the respiratory diseases increased during the period observed. I t has been generally recognized that respiratory infections and gastrointestinal illnesses are the principal causes of illness in this age period. I n Table I are shown the illnesses during the first year of life. In this group respiratory TABLE
I,
CAUSES
OF ILLNESS
WITHIN
THE
Respiratory diseases Coryza, "cold,~' pharyngitis, tonsillitis, and upper respiratory infection Otitis media with respiratory infection Laryngitis Bronchitis Influenza Pneumonia Gastrointestinal diseases Diarrhea Gastroenteritis Contagious diseases Chickenpox Rubella Whooping cough Rubeola .Poliomyelitis Mumps Roseola infantum Other
FIRST
YEAI~ OF LIFE
CASES
PEg CENT OF TOTAT,
495
72.9
388 36 12 42 13 4 130 93 37 29 9 7 6 3 3 1 19 6
57.] 5.3 1.8 6.2 1.9 0.6 19.]. ] 3.7 5.4 4.3 L4 1.1 0.9 0.4 0.4 0.1 2.8 0.9
46
TtlP
JOURNAL
OF P E D I A T R I C S
disease was the most frequent and accounted for 72.9 pe~' cent of the illnesses. Coryza, " c o l d , " and infections of the respiratory tract comprised ahnost 86 per rent of the respiratory illnesses. I n Sydenstricker's r report of :i]lnesses among a general population group, 61 per cent were due to respirato~'y infection. Ilolland s foImd that minor respiratory and acute tOlmnurdcable disease accounted for three-fourths of the illnesses of children aged less than ]5 years. Gastrointestinal illnesses were next in frequency and comprised 19.1 per tent of the total number of illnesses. The latter were aI1 cases o:f quite mild diarrhea and gastroenteritis, and none of the infants required hospital care. Con> munieable disease caused 4.3 per cent of the illnesses, chickenpox and rubella being the most f r e q u e n t Since there was s u c h a small number of eommlmieablt diseases tht rates eannot be compared with those in @odb'ey's/~ H o l l a n d ' s / ~ and Collins's ~ studies. Roseola infantum was the diagnosis in 2.8 per cent o[ the illnesses and other' diseases accounted for 0.9 per tent. 2~0
/7
15
Ail co.u~5e-~
i6
q
14
I
t2 % "~ iO
%
-/ /
-
5
6
4
I
I
--
.
I
.
.
.
.
.
J
Jan. Feb. i"Ia~ Ap~ May d~ne Jaly Auo0. Sept. Oct. Nov. Dec. Month of the y e a ~ Fig. 2.--Seasonal
incidence of illness.
A seasonal variation in the incidence of infection was expected and this tendency is cleaNy shown in Fig. 2. Tilt rate of the respiratory illnesses follows tlosely the frequency of total illnesses throughout the entire year. The peaks for both were in December and F e b r u a r y and the lowest levels were in June and July. Since there was no seasonal flnetuation in tile rate of the gastrointestinal illnesses in this group of infants, it was not depicted in the graph. I n (h'ulee and his associates'~ study the respiratory in [ections were greatest in the spring and the gastrointestinal disturbances were highest in the summer.
NOI{VAL AND K E N N E D Y : TABLE i 1 .
ILLNESSES \ V I T I I [ N FIRST
T H E DURATION OF ]~I%EAST [!~EEDINGIN ~EI,ATION q?O Tk[E :RATE OP ILLNESS ILLNESS RATE B[WPK 6 MO.
DURATION BHEAST FEEDING (5[0.)
Less
0 than 3-5 6-8 9}-
47
YEAf{ OI!' L I F E
3
AL:IS INFANTS
CAUSES
," IiESPIRATORV
55 202 59 73 28
0.33 0.49 0.37 0.32 0.32
0.27 0.37 0.31 0.25 0.25
6-12 ~[0.
ALL (2zkUSES 0.83 1.34 1.]4 1.25 ]. ] 8
I~ESPIR~ ATORY 0.58 0.98 0.73 0.88 0.93
TOTe\I, J.]0 1.83 1.51 1.57 1.50
has beeu said eoneerning the influenee of breast milk on morbidity Ornlee a n d h i s a s s o e i a l e s a, (~ found lower morbidity a n d mortality rates among breast-fed and partially breast-fed infants than among the artifieially-fed infants. Stevenson found a significant difference between the average number of respiratory infections i~1 breast-fed and in artificially-fed infants but not in the number of gastrointestinal and other infections, tIowever, Stevenson found no significant difference between the number of respiratory infections per infant in the breast-fed and the artificially-%d groups within the first six months of life but he did find a difference in the second six months of life. In Table I1 it is shown that the duration of breast feeding among the 417 infants did not influence the rate of incidence of all types o[' illness and respiratory infections t)er infant within the first year of life. The illness rate for the breast-fed babies (1.69+ 0.07 per infant) was significantly big'her than the rate for those (1J6 + 0.16 per infant) who were never put to breast at any time. This increased incidence for illness occurs during the second six months of life and is directly opposite to the conclusion reached by Stevenson. Respiratory illness showed a similar pattern, ttowever, many other faetors may influence the number of illnesses noted. Ebbs and his assoeiates '*a f o u n d that the incidence of illness in babies up to the age of 6 month and the number of deaths resulting from these illnesses were many times greater in the group whose mothers had poor prenatal diets. The supplementary diet of mothers during breast feeding' and the diets of the infants, exposure to older children and adults, and housing conditions, at'e possible factors in the incidence of illness. These factors may obliterate the influence of breast feeding. Mueh
i n this age period.
SUM3/IARY
Among 417 infants observed for attacks of illness within their first year of life, the incidence of illness was not influenced by sex. The incidence of illness was 1.63 pel" infant per year. The frequency of illness increased as tim infants approached ] year of age. There was a definite seasonal fluctuation in the incidence of' respiratory illnesses but not in the incidence of gastrointestinal ilhmsses. Respiratory illnesses comprised nearly the first year of life.
73
per
cent ot: the illnesses during
'i~
THE JOU/~NAL OF PEDIATRICS
F r o m a s t a t i s t i c a l s t a n d p o i n t t h e d u r a t i o n of b r e a s t f e e d i n g d i d n o t inf l u e n c e t h e r a t e of i l l n e s s e s f o r t h e p e r i o d s t u d i e d . H o w e v e r , i t n m s t be r e m e m b e r e d t h a t m a n y o t h e r f a c t o r s p r e d i s p o s i n g to i l l n e s s m a y h a v e o b l i t e r a t e d t h i s single influence. R.EEF~RIgNCES 1. Collins, S. D.: Pub. IIealth Rep. 63: 637, 1948. 2. Falk, L S., Xlem, Margaret C., and Sinai, Nathan: The Incidence of Illness and the Receipt and Costs o:f Medical Care Among" Representative Families; Experience in Twelve Consecutive ~onths During ~1928-1931, Chicago, 1933~ The University of Chicago Press. 3. Sydenstrieker, Edgar: Pub. Health Rep. 42: 1565, 1927. 4~. Stevenson, S. S.: J. PEDIAT. 31: 616, 1947. 5. @rulee, C. G, Sanford, HI. N., and Herron, P. H.: J. A. M. A. 103: 735, 1934. 6. Grulee, C. G., Sanford, H. N., and Schwartz, Harry: J. A. 3/2. A. 104~" 1986, 1935. 7. Sydenstrieker, Edgar: P~b. Health Rep. 41: 2069, 1926. 8. Holland, Dorothy F.: Pub. ttealth Rep. 55: 227, 194~0. 9. @odfrey~ E. S., J r . : Am. J. Pub. Health 18: 616, 1928. 10. 7Iolland, Dorothy F.: Pub. ]~ealth Rep. 55: 135, 1940. 11. Collins, S. D.: Pub. ]Iealth Rep. 50: 237, 1935. 1 2 . C-rulee, C. G, Sanford, IX. N., and Xanter-Amtoman, Jennie: J. PEDXAT. 6: 825, 1935. 13. Ebbs, J. H., Tisdall~ F. F., and Seo~zt~ W. A.: J. Nutrition 22: 515, 1941.
L T I I O U G H the morbidity rate is said to be highest in the first year of life, few artie]es in the literature supply definite information about illnesses in lhis period. The purpose of this i)ape~" is to present data obtained in a study o[ illnesses that occurred among 417 infants during their fb'st year of life. Illness was interpreted as a continuous period of " i n f e c t i o n " i'egardless of eomplieation. This definition ruled out sueh conditions as infantile eolie, injuries, operations, the more simple dermatologie conditions, and congenital defects such as clubfeet. If one condition was reported as the p r i m a r y cause and was assoeiated with other conditions, only the p r i m a r y cause was tabulate& If there was more than one cause of illness, the disease most specifically associated with the period of sickness was preferred over a minor condition which preceded or accompanied it. Records obtained in this manner were of the incidence of attacks I'ather than of illnesses in the sense of chronic illhealth.
A
The infants in this series were born of residents of Rochester, Minn., during 1944 through 194:6. Owing to the uniquely coordinated program of medical care for children in this city, most of the infants are seen at a well child clinic each month during their first year of life. For their more serious illnesses most of these ehihlren are attended by a pediatrician. To be assured that the i n f o f mation concerning the illnesses was collected from the infants' mothers at frequent intervals, only those infants were selected who had attended the Well Child C.1inie at least nine times d u r i n g their firsl year of life. At each of these conferences with the mother, the physician inquired about any illnesses that the child might have had since his last visit, and recorded the diagnosis, approximate date, and whether a physician attended the child during the illness. As a cheek that all illnesses were reported, the pediatricians' reeords on these children weI'e reviewed and a record of any additional illnesses was inserled. This selection of infants does eliminate the few children who were chronically ill and needed prolonged care by a pediatrician, or who might have died before the end of the first year, but we have included any illness that was o~:served by the mother, no matter how mild. Among this group of 417 infants there were recorded 679 illnesses, which wm'e distributed equally between the boys and tile girls. This is not in agreenlent with the illness study by Collins, ~ who found the ill,less rates for ~nales to be eonsistently greater than those for females except in the age period ] to 2 months. Data for his study were obtained from five different illness studies conducted by pe~'iodic canvasses of families within the past twenty-five years. F~'orn the Depal'lrnent of Pediatrics, Mayo Foundation and Mayo Clinic.
43
44
THE
JOURNAL
OF P E D I A T R I C S
I n eaeh survey the :families were visited at intervals of two to fOUl' months, and a record was made of any illness of the infants under observation by month of age up to twelve months. Falk and his assoeiates ~ had f o u n d in a public health survey that illnesses in the first fifteen years of life were equally distributed between the two sexes. Illness was defined by Falk as " a n y disorder that wholly or partially disabled an individual for one or more days or as an experience for which mediea] service of any kind is received. Any condition, symptom or disorder {or which drugs costing fifty cents or more are purchased is considered an illness." 2.6 ~4 --
Z0-q
t6 --
tz
l~e~?~atovy
6
..o.-,
4
0
!
Ga stt~o-intestinal
2
Birth
t
2.
3
5
6
7
I
I
5
9
/
I i0
ll
A~e -months J~'ig. 1 . - - T h e
i n e i d e n e e of i l l n e s s i n r e l a t i o n
to t h e a g e of t h e i n f a n t .
Tile incidence of illness for this group of infants was 1.63 per infant for tile age period studied. This is a higher incidenee of illness than was found by l%lk and his associates, Collins, or Sydenstrieker, a but lower than Stevenson 4 reported. Falk found that the incidence rate of illness during' the first year of life varied between 1.29 and 1.39 per infant depending on the income level of the families. Collins f o u n d an illness rate of 1.45 per person for infants less than 1 year of age. I n the Hagerstown morbidity study, a the rate was 1.59 per person for ehildren less than 5 years of age. Stevenson found among 263 infants in Bost(m, who were carefully followed in a longitudinal study of child health and development, that the average number of infeetions per infant varied from 1.79 to 2.43 per year aceording to the method of feeding. Some variations in the reported ineidence rate of illness can be aeeounted for by different definitions of illness, the variety of income groups surveyed, the geographic location of the subjects, and the ages of the individuals observed.
NORVAL AND K E N N E D Y :
ILLNESSES ~vVITHIN FIRST YEAR OF LIF E
45
Of the 417 infants in this series, 22.8 per cent were reported as not being ill during their first year of life, 28.5 per cent had one illness, 26.2 per cent had two illnesses, and 22.5 per cent had three or more. Among nearly 40,000 persons of all ages, Collins found that 48 per cent did not suffer from illness during a year, 32 per cent were ill once, 13 per cent twice, and 7 per cent three or more times. Similar figures were obtained by Falk and his associates from a study of members of 9,000 white families in seventeen states. The distribution of illnesses according to the age of the infant is shown in Fig. 1. There is a steady rise in the nmnber of illnesses from all causes as the infants approach their first birthday, as well as in the illnesses due to respiratory and gastrointestinal disease. The illnesses during the last six months of the first year are approximately three times the number during the first six months of life; this increase is of the same order among the respiratory and the g'astrointestinal diseases. Grulee and his associates 5, G investigated the morbidity from infections among 20,000 artificially-fed and breast-fed infants who were followed for as long as nine months by Chicago's I n f a n t Welfare Society during 1924 to 1929. They found a rise in the illness rate each month until the fifth month with all types of infant feeding; the rate then decreased in the breast-fed and partially breast-fed groups but in the artificially-fed group the rise continued through the ninth month. Collins found that illnesses from all causes start with a high rate for the first month of life and drop to the lowest rate in the second month, followed by a gradual increase to a level of about 1.5 illnesses per infant throughout the last half of the first year of life. The digestive diseases had a high rate in the first month of life; then the rate fell rapidly and remained quite stable throughout the first year, while the respiratory diseases increased during the period observed. I t has been generally recognized that respiratory infections and gastrointestinal illnesses are the principal causes of illness in this age period. I n Table I are shown the illnesses during the first year of life. In this group respiratory TABLE
I,
CAUSES
OF ILLNESS
WITHIN
THE
Respiratory diseases Coryza, "cold,~' pharyngitis, tonsillitis, and upper respiratory infection Otitis media with respiratory infection Laryngitis Bronchitis Influenza Pneumonia Gastrointestinal diseases Diarrhea Gastroenteritis Contagious diseases Chickenpox Rubella Whooping cough Rubeola .Poliomyelitis Mumps Roseola infantum Other
FIRST
YEAI~ OF LIFE
CASES
PEg CENT OF TOTAT,
495
72.9
388 36 12 42 13 4 130 93 37 29 9 7 6 3 3 1 19 6
57.] 5.3 1.8 6.2 1.9 0.6 19.]. ] 3.7 5.4 4.3 L4 1.1 0.9 0.4 0.4 0.1 2.8 0.9
46
TtlP
JOURNAL
OF P E D I A T R I C S
disease was the most frequent and accounted for 72.9 pe~' cent of the illnesses. Coryza, " c o l d , " and infections of the respiratory tract comprised ahnost 86 per rent of the respiratory illnesses. I n Sydenstricker's r report of :i]lnesses among a general population group, 61 per cent were due to respirato~'y infection. Ilolland s foImd that minor respiratory and acute tOlmnurdcable disease accounted for three-fourths of the illnesses of children aged less than ]5 years. Gastrointestinal illnesses were next in frequency and comprised 19.1 per tent of the total number of illnesses. The latter were aI1 cases o:f quite mild diarrhea and gastroenteritis, and none of the infants required hospital care. Con> munieable disease caused 4.3 per cent of the illnesses, chickenpox and rubella being the most f r e q u e n t Since there was s u c h a small number of eommlmieablt diseases tht rates eannot be compared with those in @odb'ey's/~ H o l l a n d ' s / ~ and Collins's ~ studies. Roseola infantum was the diagnosis in 2.8 per cent o[ the illnesses and other' diseases accounted for 0.9 per tent. 2~0
/7
15
Ail co.u~5e-~
i6
q
14
I
t2 % "~ iO
%
-/ /
-
5
6
4
I
I
--
.
I
.
.
.
.
.
J
Jan. Feb. i"Ia~ Ap~ May d~ne Jaly Auo0. Sept. Oct. Nov. Dec. Month of the y e a ~ Fig. 2.--Seasonal
incidence of illness.
A seasonal variation in the incidence of infection was expected and this tendency is cleaNy shown in Fig. 2. Tilt rate of the respiratory illnesses follows tlosely the frequency of total illnesses throughout the entire year. The peaks for both were in December and F e b r u a r y and the lowest levels were in June and July. Since there was no seasonal flnetuation in tile rate of the gastrointestinal illnesses in this group of infants, it was not depicted in the graph. I n (h'ulee and his associates'~ study the respiratory in [ections were greatest in the spring and the gastrointestinal disturbances were highest in the summer.
NOI{VAL AND K E N N E D Y : TABLE i 1 .
ILLNESSES \ V I T I I [ N FIRST
T H E DURATION OF ]~I%EAST [!~EEDINGIN ~EI,ATION q?O Tk[E :RATE OP ILLNESS ILLNESS RATE B[WPK 6 MO.
DURATION BHEAST FEEDING (5[0.)
Less
0 than 3-5 6-8 9}-
47
YEAf{ OI!' L I F E
3
AL:IS INFANTS
CAUSES
," IiESPIRATORV
55 202 59 73 28
0.33 0.49 0.37 0.32 0.32
0.27 0.37 0.31 0.25 0.25
6-12 ~[0.
ALL (2zkUSES 0.83 1.34 1.]4 1.25 ]. ] 8
I~ESPIR~ ATORY 0.58 0.98 0.73 0.88 0.93
TOTe\I, J.]0 1.83 1.51 1.57 1.50
has beeu said eoneerning the influenee of breast milk on morbidity Ornlee a n d h i s a s s o e i a l e s a, (~ found lower morbidity a n d mortality rates among breast-fed and partially breast-fed infants than among the artifieially-fed infants. Stevenson found a significant difference between the average number of respiratory infections i~1 breast-fed and in artificially-fed infants but not in the number of gastrointestinal and other infections, tIowever, Stevenson found no significant difference between the number of respiratory infections per infant in the breast-fed and the artificially-%d groups within the first six months of life but he did find a difference in the second six months of life. In Table I1 it is shown that the duration of breast feeding among the 417 infants did not influence the rate of incidence of all types o[' illness and respiratory infections t)er infant within the first year of life. The illness rate for the breast-fed babies (1.69+ 0.07 per infant) was significantly big'her than the rate for those (1J6 + 0.16 per infant) who were never put to breast at any time. This increased incidence for illness occurs during the second six months of life and is directly opposite to the conclusion reached by Stevenson. Respiratory illness showed a similar pattern, ttowever, many other faetors may influence the number of illnesses noted. Ebbs and his assoeiates '*a f o u n d that the incidence of illness in babies up to the age of 6 month and the number of deaths resulting from these illnesses were many times greater in the group whose mothers had poor prenatal diets. The supplementary diet of mothers during breast feeding' and the diets of the infants, exposure to older children and adults, and housing conditions, at'e possible factors in the incidence of illness. These factors may obliterate the influence of breast feeding. Mueh
i n this age period.
SUM3/IARY
Among 417 infants observed for attacks of illness within their first year of life, the incidence of illness was not influenced by sex. The incidence of illness was 1.63 pel" infant per year. The frequency of illness increased as tim infants approached ] year of age. There was a definite seasonal fluctuation in the incidence of' respiratory illnesses but not in the incidence of gastrointestinal ilhmsses. Respiratory illnesses comprised nearly the first year of life.
73
per
cent ot: the illnesses during
'i~
THE JOU/~NAL OF PEDIATRICS
F r o m a s t a t i s t i c a l s t a n d p o i n t t h e d u r a t i o n of b r e a s t f e e d i n g d i d n o t inf l u e n c e t h e r a t e of i l l n e s s e s f o r t h e p e r i o d s t u d i e d . H o w e v e r , i t n m s t be r e m e m b e r e d t h a t m a n y o t h e r f a c t o r s p r e d i s p o s i n g to i l l n e s s m a y h a v e o b l i t e r a t e d t h i s single influence. R.EEF~RIgNCES 1. Collins, S. D.: Pub. IIealth Rep. 63: 637, 1948. 2. Falk, L S., Xlem, Margaret C., and Sinai, Nathan: The Incidence of Illness and the Receipt and Costs o:f Medical Care Among" Representative Families; Experience in Twelve Consecutive ~onths During ~1928-1931, Chicago, 1933~ The University of Chicago Press. 3. Sydenstrieker, Edgar: Pub. Health Rep. 42: 1565, 1927. 4~. Stevenson, S. S.: J. PEDIAT. 31: 616, 1947. 5. @rulee, C. G, Sanford, HI. N., and Herron, P. H.: J. A. M. A. 103: 735, 1934. 6. Grulee, C. G., Sanford, H. N., and Schwartz, Harry: J. A. 3/2. A. 104~" 1986, 1935. 7. Sydenstrieker, Edgar: P~b. Health Rep. 41: 2069, 1926. 8. Holland, Dorothy F.: Pub. ttealth Rep. 55: 227, 194~0. 9. @odfrey~ E. S., J r . : Am. J. Pub. Health 18: 616, 1928. 10. 7Iolland, Dorothy F.: Pub. ]~ealth Rep. 55: 135, 1940. 11. Collins, S. D.: Pub. ]Iealth Rep. 50: 237, 1935. 1 2 . C-rulee, C. G, Sanford, IX. N., and Xanter-Amtoman, Jennie: J. PEDXAT. 6: 825, 1935. 13. Ebbs, J. H., Tisdall~ F. F., and Seo~zt~ W. A.: J. Nutrition 22: 515, 1941.