Seasonality of growth in Shanghai infants (n=4128) born in 11 consecutive years

The Relationship Between Children's Birth Time and Short Stature

BACKGROUND

There are few current reports on the relationship between time of birth and short stature in children. Therefore, we aimed to investigate whether there is an association between time of birth and short stature in children.

MATERIALS AND METHODS

In this study, basic information was collected from 462 children aged 2-14 years old. We collected data on gender, height, height standard deviation score (SDS), weight, body mass index (BMI), serum 25(OH)D levels, date of birth, and whether the above children were short stature. Demographic description, univariate analysis, multivariate logistic regression analysis, smooth curve fitting, and threshold effects were used to explore possible linear or non-linear relationships between children's birth time and short stature.

RESULTS

The mean age of the 462 children was 9.76 ± 3.10 years old, and 52.16% were male. A total of 129 (27.92%) children were defined as 25(OH)D insufficiency, including 107 (38.91%) in the short stature group and 22 (11.76%) in the normal stature group. Fully adjusted logistic regression showed that the risk of short stature was reduced by 56.5% in children born in summer compared with spring (P < 0.05) [odds ratio (OR): 0.435, 95% confidence interval (CI): 0.197-0.959]. A non-linear relationship was found between "sequential day of the year" and short stature from the 1st to the 250th day of the year, the risk of short stature in children is reduced by 0.6% for each day that passes (P = 0.002) (OR: 0.994, 95% CI: 0.990-0.998), and from the 250th to the 365th day of the year, the risk of short stature in children was increased by 0.8% for each day that passed (P = 0.008) (OR: 1.008, 95% CI: 1.001-1.025).

CONCLUSIONS

Children born in summer have a lower risk of short stature than spring. For children born before the 250th day of the year, "sequential day of the year" was negatively associated with short stature, and for children born after the 250th day, "sequential day of the year" was positively associated with short stature.

Early excessive growth with distinct seasonality in preschool obesity

OBJECTIVES

Healthy-weight children tend to gain weight during winter but lose weight during summer. However, overweight elementary school children have shown accelerated summertime weight gain. Whether this seasonal growth variation occurs during preschool period is of substantial interest.

METHODS

Data were derived from a nationwide retrospective cohort of nursery school children. Eight consecutive sets of longitudinal measurements on height and weight were obtained from 15 259 preschool children. Thereafter, growth in height, weight and body mass index (BMI) over a period of 6 months was calculated. Summertime growth was defined as that from April to October, whereas wintertime growth was defined as that from October to April of the following year. Longitudinal growth seasonality was analysed by classifying children according to their BMI status at the age of elementary school entry.

RESULTS

Accelerated summertime weight and BMI gain were observed among children with obesity. This distinctive growth seasonality was detected from around age 2. Children having this growth seasonality at approximately 2 years of age tended to be obese at the age of elementary school entry (OR: 3.7; 95% CI: 2.9 to 4.6; p<0.0001). In height gain, obese children were growing apparently faster than those in the other groups at all ages.

CONCLUSION

Early excessive growth with distinct seasonality was observed in preschool obese children. These findings suggest that individuals involved in child healthcare should pay closer attention to early excessive growth with distinct seasonality in preschool obesity.

Seasonality and determinants of child growth velocity and growth deficit in rural southwest Ethiopia

Background

Ethiopia faces cyclic food insecurity that alternates between pre- and post- harvest seasons. Whether seasonal variation in access to food is associated with child growth has not been assessed empirically. Understanding seasonality of child growth velocity and growth deficit helps to improve efforts to track population interventions against malnutrition. The aim of this study was assess child growth velocity, growth deficit, and their determinants in rural southwest Ethiopia.

Method

Data were obtained from four rounds of a longitudinal household survey conducted in ten districts in Oromiya Region and Southern Nations, Nationality and Peoples Region of Ethiopia, in which 1200 households were selected using multi-stage cluster sampling. Households with a child under 5 years were included in the present analyses (round 1 n = 579, round 2 n = 674, round 3 n = 674 and round 4 n = 680). The hierarchical nature of the data was taken into account during the statistical analyses by fitting a linear mixed effects model. A restricted maximum likelihood estimation method was employed in the analyses.

Result

Compared to the post-harvest season, a higher length and weight velocity were observed in pre-harvest season with an average difference of 6.4 cm/year and 0.6 kg/year compared to the post-harvest season. The mean height of children in post-harvest seasons was 5.7 cm below the WHO median reference height. The mean height of children increased an additional 3.3 cm [95% CI (2.94, 3.73)] per year in pre-harvest season compared to the post-harvest season. Similarly, the mean weight of children increased 1.0 kg [95% CI (0.91, 1.11)] per year more in the pre-harvest season compared to the post-harvest season. Children who had a low dietary diversity and were born during the lean season in both seasons had a higher linear growth deficit. Being member of a highly food insecure household was negatively associated with higher weight gain. Having experienced no illness during the previous 2 weeks was positively associated with linear growth and weight gain.

Conclusion

Child growth velocities and child growth deficits were higher in the pre-harvest season and post- harvest season respectively. Low dietary diversity and being part of a highly food insecure household were significantly risk factors for decreased linear growth and weight gain respectively.

The Use of Electronic Medical Record Data to Analyze the Association Between Atrial Fibrillation and Birth Month

OBJECTIVES

Cardiovascular disease is a condition of enormous public health concern. Recently, a population study newly revealed associations between cardiovascular diseases and birth month. Here, we investigated the association between atrial fibrillation in cardiovascular disease and birth month.

METHODS

We retrospectively extracted birth date data from 6,016 patients with atrial fibrillation (3,876 males; 2,140 females) from our electronic medical records. The number of live births in Japan fluctuates seasonally. Therefore, we corrected the number of patients for each birth month based on a Japanese population survey report. Then, a test of the significance of the association between atrial fibrillation and birth month was performed using a chi-square test. In addition, we compared the results of an analysis of patient data with that of simulated data that showed no association with birth month.

RESULTS

The deviations of birth month were not significant (overall: p = 0.631, males: p = 0.842, females: p = 0.333). The number of female patients born in the first quarter of the year was slightly higher than those born in the other quarters of the year (p = 0.030). However, by comparing the magnitudes of dispersion in the simulated data, it seems that this finding was mere coincidence.

CONCLUSION

An association between atrial fibrillation and birth month could not be confirmed in our Japanese study. However, this might be due to differences in ethnicity. Further epidemiologic studies on this topic may result in reduction of disease risk in the general population and contribute to public health.

Association between birth season and physical development in children under 3 years old residing in low-income counties in western China

OBJECTIVE

To explore the association between birth season and physical development and provide a necessary reference value to inform the implementation of public health services.

DESIGN

Cross-sectional study.

SETTING

Forty-five counties in ten provinces in western China in 2005.

SUBJECTS

A sample of 13,387 children under 3 years old and their mothers were recruited using a stratified, multistage, cluster random sampling method.

RESULTS

The results of the circular distribution analysis suggested that stunting and underweight exhibited time aggregation (Z = 32.57, P<0.05; Z = 10.42, P<0.05) among children under 3 years old. The Z - value for wasting, however, was not statistically significant (P>0.05). The generalized linear mixed models showed that children born in the summer were less likely to exhibit stunting (OR: 0.74~0.97) than were children born in the winter after adjusting for confounders, but no significant differences were identified for the other seasons. In addition, among children aged 25 to 36 months, those born in the summer and autumn were less likely to exhibit stunting after adjusting for confounders than were children born in the winter, but the association between birth in spring and stunting was not statistically significant.

CONCLUSIONS

Stunting was associated with season of birth among children under 3 years old in low-income counties in western China, especially children aged 25 to 36 months, and children born in the summer and autumn were less likely to exhibit stunting than were children born in the winter.

Wasting and Stunting—Similarities and Differences: Policy and Programmatic Implications

Wasting and stunting are often presented as two separate forms of malnutrition requiring different interventions for prevention and/or treatment. These two forms of malnutrition, however, are closely related and often occur together in the same populations and often in the same children. Wasting and stunting are both associated with increased mortality, especially when both are present in the same child. A better understanding of the pathophysiology of these two different forms of malnutrition is needed to design efficient programs. A greatly reduced muscle mass is characteristic of severe wasting, but there is indirect evidence that it also occurs in stunting. A reduced muscle mass increases the risk of death during infections and also in many other different pathological situations. Reduced muscle mass may represent a common mechanism linking wasting and stunting with increased mortality. This suggests that to decrease malnutrition-related mortality, interventions should aim at preventing both wasting and stunting, which often share common causes. Also, this suggests that treatment interventions should focus on children who are both wasted and stunted and therefore have the greatest deficits in muscle mass, instead of focusing on one or the other form of malnutrition. Interventions should also focus on young infants and children, who have a low muscle mass in relation to body weight to start with. Using mid-upper-arm circumference (MUAC) to select children in need of treatment may represent a simple way to target young wasted and stunted children efficiently in situations where these two conditions are present. Wasting is also associated with decreased fat mass. A decreased fat mass is frequent but inconsistent in stunting.

Fat secretes multiple hormones, including leptin, which may have a stimulating effect on the immune system. Depressed immunity resulting from low fat stores may also contribute to the increased mortality observed in wasting. This may represent another common mechanism linking wasting and stunting with increased mortality in situations where stunting is associated with reduced fat mass. Leptin may also have an effect on bone growth. This may explain why wasted children with low fat stores have reduced linear growth when their weight-for-height remains low. It may also explain the frequent association of stunting with previous episodes of wasting. Stunting, however, can occur in the absence of wasting and even in overweight children. Thus, food supplementation should be used with caution in populations where stunting is not associated with wasting and low fat stores.

Seasonal variation of child under nutrition in Malawi: is seasonal food availability an important factor? Findings from a national level cross-sectional study

BACKGROUND

Child under nutrition is an underlying factor in millions of under-five child deaths and poor cognitive development worldwide. Whilst many studies have examined the levels and factors associated with child under nutrition in different settings, very little has been written on the variation of child under nutrition across seasons. This study explored seasonal food availability and child morbidity as influences of child nutritional status in Malawi.

METHODS

The study used the 2004 Malawi Integrated Household Survey data. Graphical analysis of the variation of child under nutrition, child morbidity and food availability across the 12 months of the year was undertaken to display seasonal patterns over the year. Multivariate analysis was used to explore the importance of season after controlling for well-established factors that are known to influence a child's nutritional status.

RESULTS

A surprising finding is that children were less likely to be stunted and less likely to be underweight in the lean cropping season (September to February) compared to the post-harvest season (March to August). The odds ratio for stunting were 0.80 (0.72, 0.90) and the odds ratio for underweight were 0.77 (0.66, 0.90). The season when child under nutrition levels were high coincided with the period of high child morbidity in line with previous studies. Children that were ill in the two weeks prior to survey were more likely to be underweight compared to children that were not ill 1.18 (1.01, 1.38).

CONCLUSION

In Malawi child nutritional status varies across seasons and follows a seasonal pattern of childhood illness but not that of household food availability.

School year versus summer differences in child weight gain: a narrative review

The causes of the current high prevalence of overweight and obesity among children are not clearly known. Schools have been implicated in the causal chain to high child obesity prevalence. Recent studies have compared school year versus summertime changes (herein called seasonal differences) in child adiposity or related phenomena. The most common seasonal pattern in six longitudinal descriptive studies was that overweight and obese children experienced accelerated gain in weight or some BMI indicator during the summer, whereas healthy weight children gained less or not at all. Four physical activity (PA) intervention studies demonstrated that school year fitness improvements were lost during the summer. One study showed that PA declined across the summer. Another study provided conflicting results of lower total energy expenditure in the summer, but no seasonal difference in total energy expenditure after adjusting for fat-free mass. This pattern of fairly rapid seasonal differences suggests that PA is the primary factor contributing to seasonal differences in weight or BMI, but the documented seasonal pattern in PA (i.e., higher in summer) does not support this relationship. Sleep duration has also been inversely related to child adiposity. Seasonal patterns in adiposity, PA, and sleep need to be clearly established separately for overweight and healthy weight children in further longitudinal research to provide a clear focus for national policy.

Seasonal variations of neuromotor development by 14 months of age: Hamamatsu Birth Cohort for mothers and children (HBC Study)

The present study aimed at investigating whether neuromotor development, from birth to 14 months of age, shows seasonal, cyclic patterns in association with months of birth. Study participants were 742 infants enrolled in the Hamamatsu Birth Cohort (HBC) Study and followed-up from birth to the 14th month of age. Gross motor skills were assessed at the ages of 6, 10, and 14 months, using Mullen Scales of Early Learning. The score at each assessment was regressed onto a trigonometric function of months of birth, with an adjustment for potential confounders. Gross motor scores at the 6th and 10th months showed significant 1-year-cycle variations, peaking among March- and April-born infants, and among February-born infants, respectively. Changes in gross motor scores between the 10th and 14th months also showed a cyclic variation, peaking among July- and August-born infants. Due to this complementary effect, gross motor scores at the 14th month did not show seasonality. Neuromotor development showed cyclic seasonality during the first year of life. The effects brought about by month of birth disappeared around 1 year of age, and warmer months seemed to accelerate the neuromotor development.

Early growth velocities and weight gain plasticity improve linear growth in Peruvian infants

Growth velocity patterns have the potential to signal unhealthy responses to environmental insults with long-term consequences. We aimed to investigate velocities in Peruvian infants (n = 259) in relation to attained anthropometric outcomes at 12 months and to identify determinants of velocities during critical periods of infancy. From 1995 to 1997, a randomised controlled trial of maternal zinc supplementation was conducted in a peri-urban slum area of Lima. Infants were followed monthly through 1 year on a range of anthropometric measures. Three types of velocity variables were studied: (1) incremental velocity (1 months and 3 months); (2) proportional changes (% of total size gained/month); and (3) individual velocity variability [standard deviation (SD) of individual child incremental velocities]. Mean individual child SD of weight velocity was 417 g (±126). In multivariate ordinary least squares regression analyses, growth velocities in month 1 and individual weight velocity variability positively predicted attained length and weight by 12 months. Panel regression by generalised least-squares with random effects of length and weight velocities confirmed the exponentially decelerating pace of growth through infancy and the importance of birth size in driving this trajectory. This study contributes evidence to support the importance of early growth velocities and greater degrees of weight gain plasticity for attained length and weight.

Large summer weight gain in relatively overweight preschool Japanese children

BACKGROUND

Children's lifestyles have changed recently in Japan. These changes are thought to be associated with their physical growth. The aim of the present paper was to describe and interpret the growth seasonality of children attending day-nurseries in Osaka Prefecture, Japan.

METHODS

Results were based on a 6 year follow-up study of preschool children aged 0 at baseline to 6 years old at the end of the follow up. Longitudinal growth data for 148 boys and 113 girls, born between April 1990 and March 1991, attending day-nursery were obtained monthly from April 1990 through to March 1996. Children were divided into two groups: those with a normal (<17) or high (≥ 17) body mass index (BMI) at 5 years of age. Weight and height seasonal gains were estimated for each group.

RESULTS

Weight gain was higher during autumn among the group with a normal BMI at 5 years of age. Among high BMI group, weight gain was higher during autumn when they were 0 to 4 years of age, while it was higher during summer when they were 5 years of age. Height gain was higher in spring and summer in both BMI groups. Results were similar in boys and girls.

CONCLUSION

Although the findings are consistent with previous studies for normal BMI children, the present study reports new findings for children with a high BMI at 5 years of age, for whom a large weight gain occurred during summer.

Month of birth, socioeconomic background and height in rural Chinese men

This study examines the effects of birth month and socioeconomic factors on height in rural Chinese men. The analysis of sample data of 833 adult men, 18-52 years of age, collected from 600 families in rural Hebei in 2005, shows that adult men born in winter months (November to January) are, on average, 1.04 cm shorter (p<0.01) than those born during the rest of the year. In addition to the conventional OLS regression models, the household fixed and random effects models also indicate that the month-of-birth effect exists when socioeconomic variables are controlled for. The birth-month effect on height is, however, smaller than effects of socioeconomic variables, including the household registration status, household economy and father's class status.

Higher risk of zinc deficiency in New Zealand Pacific school children compared with their Māori and European counterparts: a New Zealand national survey

Few multi-ethnic national surveys have examined Zn nutriture, despite its importance for optimal growth and development during childhood. We assessed the Zn status of urban and semi-urban children aged 5–15 years from three ethnic groups in New Zealand (NZ) in the 2002 Children's National Nutrition Survey and investigated the factors predisposing them to Zn deficiency. In a 10-month cross-sectional survey, Pacific and Māori children were over-sampled permitting ethnic-specific analyses. Anthropometry, serum Zn and Zn intakes via 24 h recalls were measured. Anthropometriczscores were highest in Pacific children. Overall, mean adjusted serum Zn at 11 years was for males and females, respectively: 11·9 (95 % CI 11·5, 12·3) and 12·5 (95 % CI 12·0, 12·9) μmol/l in NZ European and Other (NZEO) children (n395); 11·9 (95 % CI 11·4, 12·4) and 12·0 (95 % CI 11·4, 12·5) μmol/l in Māori children (n379); and 11·5 (95 % CI 11·1, 11·9) and 11·4 (95 % CI 11·1, 11·8) μmol/l in Pacific children (n589). The predictors of serum Zn were age, serum Se and sex for NZEO children; serum Se and age for Pacific children; and none for Māori children. Pacific children had the highest prevalence of low serum Zn (21 (95 % CI 11, 30) %), followed by Māori children (16 (95 % CI 12, 20) %) and NZEO children (15 (95 % CI 9, 21) %). Prevalence of inadequate Zn intakes, although low, reached 8 % for Pacific children who had the lowest Zn intake/kg body weight. Pacific boys but not girls with low serum Zn had a lower mean height-for-agez-score (P < 0·007) than those with normal serum Zn. We conclude that the biochemical risk of Zn deficiency in Pacific children indicates a public health problem. However, a lack of concordance with the risk of dietary Zn inadequacy suggests the need for better defined cut-offs in children.

Month-of-birth effect on further body size in a pig model

Previous studies unanimously confirmed the existence of a dependence of human body size on the month of birth. The cause of the phenomenon has not been identified yet, although some possible causes were proposed e.g. seasonal changes of climatic and nutritional conditions. This study explored the issue in an animal model of 20,513 pigs. We found that body weights of 6-month-old pigs were the highest for subjects born in February, but for 2-month-old pigs the peak fell in May. Any statistical correlation between the month of birth and later body weight may be induced by (1) a long-term effect of the month of birth on further growth potential (LTE), or by (2) a short-term effect of seasonal factors differentiating the growth rate (STE), so we developed a mathematical method to separate the effects. The analysis proved that (1) the observed correlations resulted only from the STE, with May-June being the months of the highest growth tempo, and that (2) there was no significant LTE. The short-term effect was responsible for differences between patterns of weight for 2- and 6-month-old animals by the month of birth: since a pig monthly gain of weight increases with age, it is favorable for it to be born in February to attain the greatest weight at the age of 6 months, whereas 2-month-old piglets are heaviest when born a month or two before the May/June optimum for growth. The lack of a long-term effect of the month of birth on pigs' weight supports the hypothesis of the cultural character of factor(s) responsible for the relationship between the month of birth and later body size in humans.

The effect of the seasons of the year on malnutrition in North Korea

North Korea's economic isolation as a consequence of its recent nuclear testing could lead to another famine. In this context, the article investigates health determinants of the last famine. Birth season is a reliable proxy for nutritional and epidemiological circumstances in early life, which in turn can systematically influence later-life health outcomes such as stature. The aim of this study is to assess the effect of birth seasons on the development of heights. Height-for-age z-scores for up to 9934 pre-school children measured in 1997 during the North Korean food crisis in the decade of the 1990 s and measured in 2002, are used for the analysis. Using these data, we have verified a number of earlier studies showing that cohorts born in winter are smaller. We have also found that cohorts born in autumn are taller. Additionally, when we control for sex, birthplace, and birth year, these calendar effects remain robust. Ignoring the humanitarian dilemma of any sort, it may be concluded that in totalitarian North Korea, Pyongyang can easily influence the biological welfare of its people by interfering with the birth calendar, in order to reduce the magnitude of a potentially upcoming famine.

Body height differentiation by season of birth: Girls from Cracow, Poland

Published studies world wide demonstrate that measures of human development and health status vary depending on the month of birth but these patterns are not always consistent and sometimes even conflict. Direct factors related to the birth season that may significantly differentiate morphological and functional traits and mechanisms causing these relations have not been found so far. On the basis of cross-sectional material, gathered in the years 1983 and 2000 by the Department of Anthropology of the Academy of Physical Education in Cracow, two main hypotheses have been verified: (1) average body height differences by month of birth are statistically insignificant, (2) the magnitude of these differences does not change with time. Metric data of 4672 girls aged 5-18 years, born in 1965-1978 and 1982-1995, were used. The total sample was also subdivided into prepubertal (5-9 years) and adolescent (10-18 years) groups. The age of the individuals was calculated to the nearest day and the procedure of standardization on the interpolated values of regional norms was applied. A highly significant relationship between the birth month and average values of height was revealed in preadolescent girls. The results obtained for the entire material proved insignificant. The patterns of the month-of-birth effect on body height for girls born in 60./70. and 80./90. show high similarity, though the effect seems weaker in the latter sample. Winter proved to be the most favorable birth season for later body height.

Infant weight-for-length is positively associated with subsequent linear growth across four different populations

Several studies have documented that length gain often lags behind weight gain during infancy and early childhood, suggesting that linear growth is partly regulated by initial body mass or fatness. To investigate this hypothesis, we analysed data from four longitudinal studies on growth of infants in the first 12 months: (1) U.S. breast-fed and formula-fed infants (n = 89); (2) breast-fed infants in Ghana (n = 190); (3) normal birthweight, breast-fed infants in Honduras (n = 108); and (4) term, low-birthweight breast-fed infants in Honduras (n = 119). The dependent variable was length gain during each 3-month interval (1- 4, 2-5, 3-6, 4-7, 5-8, 6-9, 7-10, 8-11 and 9-12 months). Three main independent variables were examined: initial weight-for-length z-score (W/L), weight change during the prior 3 months, and initial skinfold thickness. Controlling for maternal height, infant sex, and initial length-for-age z-score, length gain was positively correlated with initial W/L and prior weight change during all age intervals and with initial skinfold thickness at 3 and 4 months (r = 0.15-0.36; P < 0.01). There was no evidence of a threshold effect. These associations were evident in all four populations, in both boys and girls, and in breast-fed and formula-fed infants. The consistency of this relationship across studies supports the hypothesis that linear growth is partly regulated by initial body mass or fatness in infants.

What causes seasonality of birth in schizophrenia?

An excess of winter-spring births (and/or a decrease of summer births) has consistently been observed in schizophrenia (SCZ). This observation may provide a significant clue about the causes of the disease if specific factors which cause the phenomenon can be determined. This paper reviews several studies which investigated factors correlated with this observation in SCZ, in an attempt to determine which factors more likely cause the seasonality. Among the candidates of the factors are meteorological variables (such as ambient temperature), several infections, maternal hormones, sperm quality, nutrition and external toxins. A variation of procreation might also have an effect. Among the factors, the most extensively studied are temperature and viral infections. Some of them have appeared promising, but further studies are definitely required. Several challenges, including complicated correlations of the factors and determination of the susceptible period during pregnancy, need to be overcome. Comparisons of the data from areas and cohorts with different patterns of the candidate factors may be helpful. Animal studies may also help investigate the molecular and physiological mechanisms of the phenomenon.

Supplementary feeding of underweight, stunted Malawian children with a ready-to-use food

OBJECTIVE

Maize and soy flour mixes are often used in the treatment of moderate malnutrition in Malawi. Their efficacy has not been formally evaluated. A recently developed ready-to-use food (RTUF) effectively promotes growth among severely malnourished children. The authors compared the effect of maize and soy flour with that of RTUF in the home treatment of moderately malnourished children.

METHODS

Sixty-one underweight, stunted children 42 to 60 months of age were recruited in rural Malawi, in southeastern Africa. They received either RTUF or maize and soy flour for 12 weeks. Both supplements provided 2 MJ (500Kcal) of energy daily but had different energy and nutrient densities. Outcome variables were weight and height gain and dietary intake.

RESULTS

Before intervention, the mean dietary intake and weight and height gain were similar in the two groups. During the supplementation phase, the consumption of staple food fell among children receiving maize and soy flour but not among those receiving RTUF. There was thus higher intake of energy, fat, iron, and zinc in the RTUF group. Both supplements resulted in modest weight gain, but the effect lasted longer after RTUF supplementation. Height gain was not affected in either group. Periodic 24-hour dietary recalls suggested that the children received only 30% and 43%, respectively, of the supplementary RTUF and maize and soy flour provided.

CONCLUSIONS

RTUF is an acceptable alternative to maize and soy flour for dietary supplementation of moderately malnourished children. Approaches aimed at increasing the consumption of supplementary food by the selected recipients are needed.

Seasonality of growth and the relationship between weight and height gain in children under three years of age in rural Malawi

AIM

To describe the seasonal pattern of growth and analyse the relationship between weight and height gain in children under 3 y of age.

METHODS

A population-based cohort of 767 children was prospectively followed from birth until 36 mo of age in rural Malawi, southeast Africa. Weight and height measurements were collected at monthly intervals until 18 mo of age and quarterly thereafter. Gains in weight and height and prevalence of malnutrition in different seasons were calculated. The relationship between weight and height gain was analysed using a series of correlation analyses.

RESULTS

Both weight gain and linear growth velocity showed an age-dependent seasonal pattern. After infancy, periods of maximal or minimal height increments systematically occurred 3 mo after those for weight gain. The prevalence of malnutrition also followed a seasonal pattern, peaking a few months after periods of reduced growth. Despite the overall pattern, weight gain and subsequent linear growth were not correlated on an individual level. At any point, however, a child's weight for height was directly, albeit weakly, correlated to height gain in the subsequent 3-mo interval.

CONCLUSION

Growth of children under 3 y of age followed an age-dependent seasonal pattern. The poor correlation between children's weight and height increments suggests that seasonality affected weight gain and linear growth through different mechanisms.