American Research on Seasonal Variation in Stature and Body Weight.

The Journal of Pediatrics, Volume 10, Issue 6, June 1937, p. 819-831.

 

Critical Reviews

 

A REVIEW OF AMERICAN RESEARCH ON SEASONAL VARIATION IN STATURE AND BODY WEIGHT

 

EVERETT L. MARSHALL, PH.D.NORMAL, ILL.[1]

 

Over a century and a half has passed since the first reported observation was published on the relation between the season of the year and growth in stature. Research literature for the interim between 1777 and the present gives evidence of a recurrent interest in the factor of season as related to bodily size and fluctuation in rate of growth.  In the United States no less than 23 studies on seasonal variation have appeared to date.  It is thus timely that a critical review be made available that will provide a synthetic picture of the current status of American research on this problem.

 

While the central purpose of this paper is to review American research bearing on the question on whether or not there exists a relation between the season of the year and growth in body weight or in total stature, it will be advantageous at various points to articulate American research with the larger body of European research.

 

The earliest findings on seasonal variation were reported by Buffon[2] in his “Histoire Naturelle” in 1777.  This report was based on stature observations taken on a single individual by Montbeillard who measured his oldest son semiannually from the date of his birth in 1759 until he was nearly eighteen years of age. He found no seasonal variation difference under five years of age. Between the ages of five and ten the stature increments in the summer months were nearly double those in the winter months.  Beyond ten years of age the increase continued to be greater in the summer than in the winter but this difference was less marked.

 

The first reference to seasonal variation in growth published in America was made by a Doctor Nichols in discussing Bowditch’s 1872 paper.  Nichols stated:“...that five-sixths of his own height was due to growth during the summer months, he having been measured every April and September from the age of six months to that of twenty-one years.”[3] (P. 435).

 

Wretlind[4] [5] who weighed a number of Swedish girls before and after summer vacation, was the first (1878) to find differential weight increments for a group.  He attributed the large gain made in the summer months to the effects of the sun and freedom from school but it remained for Malling-Hansen[6]  [7] in 1883 to explain the phenomenon as seasonal variation and to substantiate the findings with his own observations on Danish children.

 

The earliest scientific investigation on seasonal variation in growth in America was reported by Hitchings and Fitz[8]and will be discussed subsequently in greater detail. In reviewing the American investigations, each one will be placed in one of three groups according to the ages of the subjects studied. The first group deals entirely with newborn infants, the second with infants and preschool children, and the third with children of school age or above.

 

 

NEWBORN INFANTS

 

In 1920 Faber[9] reported the first work on seasonal variation in birth weights in America. His observations extended over a period of thirteen years and included birth weights of 299 boys and 281 girls. These were distributed throughout the calendar year and were obtained at the baby clinic of Stanford University Medical School in San Francisco. Considering each sex separately, the mean birth weight was calculated for each quarter of the year, i.e., January-March, April-June, July-September, and October-December. The results show that there was no seasonal variation in the birth weights of girls but for boys the mean birth weight in the January-March quarter exceeded that in the July-September quarter by 150 grams. The mean birth weight of the six-month period from October to March was 100 grams larger than the mean for the six-month period between April and September.

 

The next study on birth weights was made by Brenton[10] and appeared in 1922. It was based on more than 2,000 Minnesota birth records taken at the Minnesota General Hospital, The Swedish Hospital, and the University Hospital during the four-year period, 1915-1919. The mean birth weight for each sex was computed for each month of each year and later combined to arrive at an average for each month of the year. Although a slight fluctuation occurred from month to month, no significant or consistent seasonal variation was found for either sex.

 

Bakwin and Bakwin[11] in 1929 reported the results of a study involving 3,315 birth weights for the years 1926-1927 at Bellevue Hospital, New York. The mean birth weight for each quarter of the year was found but no appreciable difference was noted. In 1934, the same investigators[12] published the results of another study with 1,219 newborn infants as subjects. The mean birth length in addition to mean birth weight was determined for each quarter but no seasonal difference for either measurement was found. The sex of the subjects was not stated in either study.

 

The birth weights of 4,799 infants from Iowa City, Atlanta, St. Petersburg, Los Angeles, and New Haven were analyzed by Bivings[13] in 1934. Without differentiation as to sex, he found that there was a tendency for birth weights to follow the curve of sunshine – low in fall and winter (mean of 7 pounds 4 ounces) and high in spring and summer (mean of 7 pounds 7 ounces). However, no seasonal variation was noted in the birth weight of the Iowa City infants.

 

An investigation to determine the influence of seasons on weight loss in infants during the first two weeks of life was made by Bakwin and Bakwin in 1929 (see footnote 11).  The mean weight loss for each month was figured from records of 3,315 infants born at Bellevue Hospital, New York, in 1926-27. It was found that for both sexes the mean weight loss in the winter months was 8.78 per cent of the birth weight while in the summer months it was 7.5 per cent of the birth weight or 15 per cent less than in the winter months.

 

Information concerning race and measurement procedures was lacking in all the studies and only in the investigations by Bakwin and Bakwin was socio-economic status of the subjects indicated.

 

Summary. – The results of the five studies on birth weight and one on total birth length are indicated in Table I.

 

TABLE I.

 

PERIODS OF MAXIMUM AND MINIMUM BIRTH WEIGHTAS FOUND BY FIVE AMERICAN INVESTIGATORS

 

INVESTIGATOR	SUBJECT	PERIOD OF MAXIMUM BIRTH WEIGHT	PERIOD OF MINIMUM BIRTH WEIGHT
Faber 1920	299 boys	Winter	summer
Faber 1920	281 girls	None	none
Brenton 1922	52 boys	None	none
Brenton 1922	979 girls	None	none
Bakwin and Bakwin 1929	3,315 boys and girls	None	none
Bakwin and Bakwin 1934	1,219 boys and girls	None	none
Bivings 1934	4,799 infants	spring-summer	fall-winter

 

NB: Bakwin 1934 also investigated total birth length for this group but found no seasonal variation.

 

Three of the investigators found no seasonal variation in birth weight for either sex while the fourth investigator found it for but not for girls. The study by the fifth investigator showed that birth weights for about 5,000 infants (sex not stated) were larger in spring and summer than those for fall and winter.

 

In contrast with these results, eleven European studies on approximately 100,000 infants indicate that the period of maximum birth weight occurs in the summer and fall while the minimum occurs in winter and spring. One European investigator found that infants born in the summer were lighter than infants born in the winter while a second investigator found no seasonal variation. The study on seasonal variation in weight loss following birth reveals that in both sexes the loss in the winter months was 15 per cent greater than in the summer months.

 

INFANCY AND PRESCHOOL YEARS

 

Seasonal variation in weight gains for the first two years of life was reported by Bleyer[14] in 1917. The data were accumulated over a five-year period prior to 1917 from 3,800 weight records of 1,000 infants at the Well Baby Clinic of Washington University, St. Louis. An average of three weighings at monthly intervals were taken on each subject and none were included who showed signs of illness on the weighing day.

 

The first-year infants showed the largest gain in weight in the summer months but the second-year infants apparently had two maxima, one in February and March and another in October with a minimum in June. In considering the results, that fact that the data are discontinuous (subjects not measured for 12 consecutive months) should be recognized. The sex of the infants was not stated.

 

Faber[15] kept records on 200 breast- and bottle-fed infants and reported that maximum growth of the former group occurred in March and November and for the latter in February and August.  Careful inspection of his graphs does not reveal a marked seasonal growth trend since there are numerous fluctuations but it seemed to be slightly the best for gains in both groups in the autumn months.

 

Berkson[16] in 1930 presented statistical evidence of a seasonal cycle in growth by analyzing the data in Woodbury’s report, “Stature and Weight of Children Under Six Years of Age.”  Means, each based on approximately 15,000 cases, were available for stature and weight below seventy-two.  By comparing the theoretical value of the mean for any given month of age as read from a parabolic curve fitted to the means by least squares with the obtained means for that age, Berkson obtained a statistically significant difference at many ages.  In consideration of these results, he concluded that there is a seasonal variation in growth because most of the obtained means above the theoretical  means came in one season of the year and those below came in another season.  He did not state the season in which the rate of growth appeared to be most rapid.

 

Wallis[17] computed the main gain in stature and weight for two periods, November to May and May to November for 120 New York private school children between the ages of two and eight years.  Stature was measured without shoes and weight was taken in the nude. The measurements which cover a five-year period, 1926-1930, were taken by the person making the investigation. Each sex was treated separately and the following conclusions were made:

 

That time of the year does not affect increments of stature and therefore a large proportion of spring or winter measurements in any age group would not emphasize or weaken the expected gain . . . This is in accord with recent belief that under good environmental conditions there is no real seasonal variation in the amount of a child’s growth (Wallis p. 31).

 

No seasonal differences in amount of weight gained were found among the New York children. The increments of weight conform closely to those of stature in illustrating the absence of seasonal influence on the increase of bulk (Wallis p. 37).

 

In 1931, the same year in which Wallis’ publication appeared, Mckay and Brown[18] reported the results of a three-year investigation covering the same age range.  Consecutive monthly measurements of height and weight for a period of one year on 114 Ohio preschool children, found by a pediatrician to be in good physical condition, constituted the data for the study.  Indoor clothing minus shoes and sweaters was worn when weight was taken and stature was secured with the subject in stocking feet. The measurements were made about the same time of day each month by one investigator and were checked by another.

 

The mean monthly increments were determined but for purposes of this study the year was divided into two periods of six months each – May to October and November to April.  The same trends were found for each sex. Conclusions from the study were:

 

There is a decided tendency toward a seasonal variation in the rate of growth in weight of preschool children, the period of most rapid growth being in the late summer and early fall, with the period of minimum gain in winter and spring.

 

Seasonal variations in increase in height were so small as to be insignificant. This may indicate that as far as increases in height are concerned, environment is less a factor than is the case with increase in weight.[19]

 

Summary.  -  The two investigations on stature  (McKay and Brown, and Wallis) reveal no seasonal variation in growth rate for either sex. The four studies dealing with seasonal variation in weight gains in infants and preschool children are summarized in Table II.  It is noted that 1) three investigators found the summer and autumn months most conducive to weight gains, and 2) no seasonal variation in weight increments was found by the fourth investigator. The results of European investigations on this age range are so inconclusive that a comparison would not be profitable.

 

 

TABLE II

 

PERIOD OF MAXIMUM AND MINIMUM WEIGHT INCREMENTS FOR INFANTS AND PRESCHOOL CHILDREN FOUND BY FOUR INVESTIGATORS

 

 

INVESTIGATOR	SUBJECT	PERIOD OF MAXIMUM CHANGE	PERIOD OF MINIMUM CHANGE
Faber 1920	200 infants	fall	spring
Bleyer 1917	1,000 infants	summer	late spring
Wallis 1931	About 60 boys	none	none
Wallis 1931	About 60 girls	none	none
Mckay and Brown 1931	About 60 boys	Summer-fall	Winter-spring
McKay and Brown 1931	About 60 girls	Summer-fall	Winter-spring

 

SCHOOL AGE OR ABOVE

 

As previously stated, Hitchings and Fitz[20] published the first quantitative American study on seasonal Variation in 1901. The subjects were 20 boys between seven and fourteen years of age at the Dedlam Boys’ Home, a branch of the Boston Children’s Friend Society. Weight was taken weekly in the nude and height was measured quarterly for an unknown period of years. Findings from the investigation are:

 

The variations in weight amounting to as much as five pounds were observed in most of the boys from week to week. The variations were so numerous and so marked as to suggest that any single test of an individual is liable to a plus or minus error of several pounds and that successive weighings are necessary for accuracy.

 

Over 90 per cent of the total increase in weight occurred during the period from June to December.

 

During the period from January to June the weight fluctuated without definite gain or loss, constituting a period of minimum growth.

 

The general form of the curve of growth in weight was found common to all the individuals studied (20), covering the ages seven to fourteen. The larger minor fluctuations were also found to be common to the majority of the boys, suggesting that the causes were general rather than individual, and that growth throughout this age period has the same general seasonal variation.

 

Growth in height in the majority of cases showed either a continuous increase at the same rate throughout the year or more rapid growth during the period of most rapid growth in weight. Only three boys showed correspondence with Malling-Hansen’s conclusions, that is, more rapid growth in height during the resting period of growth in weight. (Hitching and Fitz p. 511 and 512).

 

The preceding statements, although based on few cases, merit consideration in the planning of any study on seasonal variation in growth.

 

In 1918, Holt[21] reported the results of a study on seasonal variation in weight and stature. The mean weight increment for two periods, November to May and May to November, was secured for 703 boys ranging in ages from five to sixteen in the Browning School, New York. The average gain was one and one-fourth pounds greater in the May-November period than in the November-May period.

 

Mean monthly height increments on 544 boys were found to be 0.36 inch larger in the summer months than in the winter months. Holt believed this due to a more active life and lack of colds and diseases in the summer. A description of the measurement conditions were lacking.

 

A major investigation on seasonal variation in weight was conducted by Porter[22] and extended over an eight-year period. Starting in 1911, Porter secured weight and height on several thousand of the youngest school children in Boston. With numerous exceptions, he was able to observe these two measurements monthly on the same children until 1919. The clothing[23] worn by the subjects at the time of weighing was shown by Porter to have no effect on the results. For all boys born in 1905, the mean monthly gain in weight from January through May was 0.21 pound and from June through December was 0.77 pound. The same trend was noted in each of the eight years of the investigation. No seasonal variation in stature gain had been found by Porter at the time of publication of the results on weight gain.

 

A study of seasonal variation in weight and height was made by Hunt, Johnson and Lincoln[24] on two groups of Russian and Austrian boys in New York City in 1919-20. A nutrition class of 44 boys between the ages of five and seven who averaged 11.6 per cent underweight and an equal number of control boys who averaged 0.83 per cent underweight in September, 1919, were weighed and measured in October, February, June and October.  Both measurements were taken without shoes or coats but no account of the technique employed was given. The results show that the October-February period was most conducive to weight gains for both groups although more marked for the nutrition class. Height increments were greater for both groups in the February-June and June-October periods.

 

Holt and Fales[25] in 1920-22 investigated periodic growth of children in a Catholic institution for the poor. They secured 2,995 monthly weights on 151 boys and 195 girls of French, Italian, Spanish and Irish parentage. Each subject was weighed from one to twelve times, the weight of the clothes being subtracted from the observed weight in each instance. According to the authors, the general physical condition was above that of children in private homes because they followed a routine schedule of living habits. The results indicate that while wide fluctuations occurred from month to month, little if any seasonal variation in weight occurred for these institutional children.  The mean June-to-December gain for 187 girls was 3.26 pounds and the mean December-to-June gain for 144 girls was 3.34 pounds. For 113 boys in the summer months the mean gain was 3.50 pounds while in the winter months for 85 boys it was 2.44 pounds.

 

Another study on New York City children was carried out by Gebhart[26] . He took consecutive monthly weights on 363 Italian boys and 614 Italian girls between two and twelve years of age for periods of three to five months each.  The average period of observation was 3.8 months for boys and 4.5 months for girls. The average monthly gain for each age and sex was computed but because there were so few in each age group the average monthly gains were converted by proper weightings into gains for the nine-year-old group since the greatest number was in this group. The conversion was accomplished by multiplying the monthly gain for each age by the percentage ratio between the average expected annual gain for that age and the average expected annual gain for the nine-year-olds. The expected annual gains below six years of age were taken from Woodbury’s figures and those above six years were from Burk-Boas. Weight was taken in indoor clothing but no other account of technique was given. The validity of his procedure of combining short periods of observations to determine the amount of seasonal variation in weight may be questioned. The results show that the greatest gain in weight for both sexes occurred in September, October, and November while the least gain occurred in May and June.

 

Dividing the year into three equal parts, Veeder and Rohlfing[27] made weight observations in October, January, and May on 534 selected boys between the ages ten and eighteen at the St. Louis Country Day School. The time of day or order of measurement was not given but weight was taken in the nude and all records of sick, injured, underweight, and overweight boys were excluded. There were between 50 and 97 subjects in each age group except the eighteen-year-old one which had 24. The boys between the ages of ten and fourteen gained weight fairly uniformly throughout the year but from age fifteen to eighteen most of the gain occurred in the October-to-January period of the year. The authors pointed out that the average gain cannot be applied to the individual rigidly since there is a wide range used in obtaining the average.

 

In 1926, Porter and Baird[28] reported that at certain equal ages in months, two groups of boys, one born in February and the other in August, differed markedly in median weight.  The February group was heavier at some ages (107 and 109 months), the August group at other ages (109 and 121 months), while the two were approximately equal at any age in months which was divisible by 12 (72, 84, or 96).

 

The authors explained this phenomenon on the basis of Porter’s findings on seasonal variation in 1920[29]. It was noted that the advantage held by each group appeared at regular intervals depending on the number of good growing months which each one had had. The same trend occurred for both sexes for those individuals born between January 1 and June 30 and those born between July 1 and December 31. The number of cases was not given but the results seem to substantiate Porter’s previous findings.

 

Monthly measurements of stature and weight on 833 children for a period of one year were obtained by Emerson.[30]  Eighty per cent of these children who represented three geographic localities, New York, Toronto, and Honolulu, made irregular gains in weight. Although no seasonal trend for weight was found by Emerson, he was of the opinion that the regular monthly increment of the remaining 20 per cent was contrary to expectations. Stature gains appeared not to be influenced by seasons. Other than the fact that “measurements were free from any gross error of clothing or posture,” nothing is known concerning the procedure or sex.

 

From 1920 to 1928, Gould[31] secured stature and weight measurements in the fall and spring on 875 college girls for a period of four years each.  The mean increase in stature in four years was only 0.33 inch but 0.27 inch of it occurred in the winter months.  There was a mean weight increment of less than one pound for the same period but during the winter months a mean decrement of about one pound was noted while a slightly larger increment occurred in the summer months.

 

Between 1925 and 1929, an unpublished study of seasonal variation in weight of children attending the Kansas State School for the Deaf was made by Chaney and Justin.[32]  Three groups of each sex between the ages of six and ten furnished the data for the study. One group received two medium-sized oranges daily in addition to their regular fare, another group received daily treatment from an Alpine Sun Lamp while the third was a control group. With a few exceptions, monthly weights were secured on about 40 boys and 40 girls for the three school years 1926-1929 but for the purpose of this study the school year was broken into two parts – September through December and January through April. Weight was taken at the same hour each observation period with the subject in indoor clothing but without shoes, sweaters, or coats.  Each year was considered separately and therefore results were computed on 187 “case years.”

 

The investigators found the gain in weight to be greatest in all groups in the fall months for children between six and nine years of age but no significant difference was noted for ten-year olds.

 

An important investigation on weight increments was reported in 1933 by Palmer[33] as part of a health demonstration project at Hagerstown, Maryland. The subjects for this study were 2,500 native-born white children between the ages of sex and sixteen  who were in attendance at the eight elementary schools of Hagerstown. Weights on the children were secured each school month from September, 1923, to May, 1928.  Grades 1,2,3, and 4 were used for the first year; 2,3,4, and 5 the second year, etc.  Children with less than 80 per cent of a complete record for four of the five years were not used in the analysis.

 

One person took all the weights with the subjects wearing only regular indoor clothing without shoes. Palmer pointed out the validity of this procedure since the greatest gains in weight did not occur when heavier garments were worn by the children using them nor did the smallest gain occur when the heaviest garments were discarded. The day of the month varied as did the time of day. Palmer felt that the time of day was negligible and he made corrections for the difference in number of days between weighing periods. The children were placed in one-year age groups using the age of the birthday nearest January first and the exact mean age of each group since this was considered more accurate.

 

A table was compiled which shows the number of days for each age and sex, the number of cases, and mean gain for each period indicated. There is also a graph which shows the fluctuation in the gain in weight by month for each of the ten age groups used.  The procedure employed in making the statistical analysis was carefully described.

 

Palmer summarized his findings in relation to seasonal variation in weight as follows:

 

Maximum rates of average growth in weight are observed during the fall months, intermediate rates during the winter, and minimum rates during the spring. The average rate of growth during the summer period is approximately equal to the rates observed during February and March. The same cyclic changes are observed and for each yearly age group from the sixth through the fourteenth year.  These findings are in agreement, with few exceptions, with the previous work on the subject.[34] (p. 231).

 

Davenport, Steggarda, and Drager[35] in a study of Letchworth Village boys noted that:

 

. . . Growth in stature in our series is most rapid in the spring; while growth in weight is most rapid at the same time and also hardly less so in the autumn. There is a physiologic need for autumnal acceleration in weight that hardly exists for stature. (p. 283).

 

The last statement of the preceding quotation is taken to mean that the extra weight acts as an added protection against winter cold. The number of subjects and conditions surrounding the measurements were not given for this study.

 

One of the most recent studies on seasonal variation and also one of the most thoroughly executed was published in 1935 by Whitacre.[36] Observations were made on 2,542 white, Mexican, and negro boys and girls between the ages of five and nineteen in attendance in three San Antonio public schools with division as to race and sex as follows:

 

 

RACE	BOYS	GIRLS	TOTAL
White	519	462	981
Negro	362	369	731
Mexican	421	409	830
Total	1,302	1,240	2,542

 

Weight was taken monthly from January 1929 to April 1931 except in summer vacation. A periodically checked scales was used and each child removed his clothes and wore a robe, the weight of which was subtracted from the observed weight to give the child’s actual weight. Height was taken once a semester or five times in all by means of a Baldwin measuring tape fastened securely to a specially constructed vertical board. All measurements were taken two or more times to insure accuracy.

 

Individuals were weighed at the same time of day as far as possible and each child went to the toilet to empty the bladder before weighings. The longest interval between weighings during the school year was forty-two days in October 1929 and the shortest was twenty days in November 1929. The number of weights secured each month varied because of changes, absentees, and because a record of loss in weight over the weight at the preceding weighing period due to illness was not used.  Weights as great as, or larger than, preceding weights were considered valid and were used even though the child had been ill. Age was figured from January first and was used throughout the calendar year.

 

The following excerpts from Whitacre’s study explain some of the procedure and give the results of the investigation.

 

Evidence of seasonal variation of growth in weight was sought on the bases of 1) average net gains per child derived from group weights, 2) comparison of the contribution made by gainers and losers to the net monthly gain, 3) examination of the individual records of 98 pupils (42 white, 28 each of Mexican and negro) who showed no loss between any two consecutive weighings. The spring season included February, March, and April; the summer period extended from May through September; and fall included October, November, December, and January. (p.69).

 

The effect of seasons on weight gains for each of the three races is as follows:

 

The results in all analyses show that race likenesses are much more pronounced and consistent than race differences. For all three races, fall was slightly the best season for gaining . . . Among the three races, October was conspicuous for consistently excellent gains (from 11.3 per cent to 16.1 per cent of the yearly gain), and April, for uniformly poor gains (from 1.4 per cent to 6.4 per cent of the yearly gain).

 

The records of individual monthly weight changes show that all three races have higher ratios of gainers agreed with the trends shown from group weights . . . . Each child should be regarded individually in his course of growth. A child’s failure to gain should not be attributed complacently to the season of the year. Too much departure from regularity of gain calls for special attention, although the degree of uniformity to be expected in normal growth must be determined by further study.

 

Seasonal variation of growth in weight appeared not to be influenced by sex, age, birth-month, type of body build, or living conditions as indicated by the average number of rooms per person in the house and the presence or absence of a bathroom.

 

No explanation of the excellent gains made in October or the poor gains in April was afforded by examination of the records of weight changes in relation to the records 1) of food eaten for from two to four days within the weighing period, 2) of the minor illnesses, especially colds, or 3) of climatic conditions as indicated by U.S. Weather Bureau records. (pp 69-71).

 

Findings on height increments are:

 

Average monthly gains in height, both standing and sitting, for both the entire group of each race and age groups of white and negro children show exceedingly small and negligible differences in spring-to-fall and fall-to-spring periods . . . . It appears from the data of this study that growth in height was relatively uniform through the year, or perhaps marked difference in rate was confined to shorter time intervals than those used in this study. (p.71).

 

Summary. – The results of the ten American studies on seasonal variation in weight gains of school children of one or both sexes are shown in Table III.

 

TABLE III

 

PERIODS OF MAXIMUM AND MINIMUM GAIN IN WEIGHT OF CHILDREN OF SCHOOL AGE OR ABOVE AS FOUND BY ELEVEN INVESTIGATORS

 

INVESTIGATOR	SUBJECT	PERIOD OF MAXIMUM GAIN	PERIOD OF MINIMUM GAIN
Hitchings and Fitz 1901	20 boys	June-December	January-May
Holt 1918	703 boys	May-November	November-May
Porter 1920	Several thousand boys and girls	June-December	January-March
Hunt, Johnson and Lincoln 1921	90 boys	October-February	June-September
Holt and Fales 1923	113 boys	June-December	December – June
Holt and Fales 1923	187 girls	none	None
Gebhart 1924	363 boys	Sept- Nov	May-June
Gebhart 1924	614 girls	Sept - Nov	May-June
Veeder and Rohlfing 1927	534 boys	October-January	May-September
Emerson 1927	833 children	none	None
Chaney and Justin 1930	187 boys and girls	Sep - Dec	January – April
Palmer 1933	About 1,250 boys	Sep - Dec	March – June
Palmer 1933	About 1,250 girls	Sep - Dec	March – June
Whitacre 1935	1,302 boys	Oct - Dec	April
Whitacre 1935	1,240 girls	Oct - Dec	April

 

No seasonal variation was reported in two, one on a group of which sex is not known and the other on a group of girls in an institution. The latter study marks the only sex difference reported – the boys who were observed by the same investigator showed a seasonal variation in weight gains which agrees with the results of the other eight investigations. Fall was found to be the optimum time of year for weight increase with summer second best while winter and spring were least conducive to growth in weight. The three major investigations[37] each based on consecutive measurements of 2,500 children agree on these results as do the majority of European studies.

 

Four of the six investigations on seasonal variation in stature yielded results indicating an absence of seasonal growth. The other two investigators reported that the spring and summer months were the most favorable to increase in stature with winter the least favorable. Table IV shows the results.

 

TABLE VI

 

PERIODS OF MAXIMUM AND MINIMUM GAIN IN STATURE OF CHILDREN OF SCHOOL AGE OR ABOVE AS FOUND BY SIX INVESTIGATORS

 

INVESTIGATOR	SUBJECT	PERIOD OF MAXIMUM GAIN	PERIOD OF MINIMUM GAIN
Hitchings and Fitz 1901	20 boys	none	none
Holt 1918	544 boys	summer	winter
Porter 1920	Several thousand boys and girls	none	none
Hunt, Johnson and Lincoln 1920	90 boys	February - October	October - February
Emerson 1927	833 children	none	none
Whitacre 1935	1,302 boys	none	none
Whitacre 1935	1,240 girls	none	none

 

 

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