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

Month of birth and height. A case study in rural Spain

INTRODUCTION

Season of birth correlates to a wide range of health conditions throughout life measured by anthropometrics. This study explores whether the month of birth and weather during gestation influence male adult height, based on Spain's rural population before the end of the modernization process.

METHODS

The database of heights (N = 16.266) is composed of conscripts who reached the age of 21 between 1908 and 1985 (birth cohorts 1886-1965). The population sample has been taken from a municipality in inner Spain: Hellín, in the region of Castilla-La Mancha, mainly an agrarian area, with poor resources and low income until the 1970 s/1980 s. Two different methodologies have been implemented: a harmonic regression using sinusoidal covariables and a random forest model.

RESULTS

we find that being born at the end of the summer and during the autumn was favorable to height. The birth month with the highest statures is September, with heights 0.5 cm above the annual average and 0.9 cm above February, the birth month with the lowest average height. Furthermore, we can observe that rainfall and temperature during gestation had little additional influence due to a substitution effect with the birth month variable.

CONCLUSIONS

Our results suggest that the seasonal effects on height can be significant and that it can be partially affected by environmental factors during early life. Our findings could be of interest for low-income populations and developing rural societies.

Maternal Brown Fat Thermogenesis Programs Glucose Tolerance in the Male Offspring

Environmental temperature is a driving factor in evolution, and it is commonly assumed that metabolic adaptations to cold climates are the result of transgenerational selection. Here, we show in mice that even minor changes in maternal thermogenesis alter the metabolic phenotype already in the next generation. Male offspring of mothers genetically lacking brown adipose tissue (BAT) thermogenesis display increased lean mass and improved glucose tolerance as adults, while females are unaffected. The phenotype is replicated in offspring of mothers kept at thermoneutrality; conversely, mothers with higher gestational BAT thermogenesis produce male offspring with reduced lean mass and impaired glucose tolerance. Running-wheel exercise reverses the offspring's metabolic impairments, pointing to the muscle as target of these fetal programming effects. Our data demonstrate that gestational BAT activation negatively affects metabolic health of the male offspring; however, these unfavorable fetal programming effects may be negated by active lifestyle.

A systematic review on the association of month and season of birth with future anthropometric measures

BACKGROUND

Prenatal factors might have some health impacts later in life. This study aims to systematically review the current literature on the association between season and month of birth with birth weight as well as with weight status in childhood.

METHODS

The search process was conducted in electronic databases, including papers published until April 2019 in ISI Web of Science, PubMed, Scopus, and Google Scholar. The following search strategy was used with MeSH terms: ("Seasons"[Mesh]) AND ("Obesity"[Mesh] OR "Pediatric Obesity"[Mesh] OR "Obesity, Abdominal"[Mesh] OR "Overweight"[Mesh] OR "Birth Weight"[Mesh] OR "Body Height"[Mesh]). After the selection process, 50 papers were included in this systematic review.

RESULTS

This review showed that individuals who are born in cold season (winter month) have higher body mass index (BMI) and weight in childhood. Birth in March was associated with lower weight and BMI in boys according to most studies. All studies, except one of them, showed that season/month of birth was not associated with birth weight.

CONCLUSIONS

This systematic review confirms a relationship between season and month of birth with birth weight and body size in childhood; however, the impact of confounding factors, for example, vitamin D status, should be considered in the underlying pathway of this association.

IMPACT

The results provide evidence for the effect of season and month of birth on body size in childhood. Our systematic review suggests that there is no pattern between birth weight and season/month of birth, and the occurrence of low birth weight was more frequent among infants who were born in summer than others. Further research should focus on identifying the impact of confounding factors, for example, vitamin D status in the underlying pathway of this association. There was response to the controversial findings about the effect of environment factors, such as season and month of birth, and future anthropometric indices, such as obesity, weight, height, and birth weight. Obesity is a complex and multifactorial disorder; the findings of the current study would be useful in determining the relationship pathway between the season and the month of birth with other underlying factors for childhood obesity.

Season of birth and biomarkers of early-life environment

OBJECTIVE

Early-life conditions play an important role in human development, affecting health status and survival. Conditions in utero partly depend on the external environment and thus vary in relation to the season of birth. The aim of this study was to investigate if people born in different seasons of the year differ in values of biomarkers that reflect conditions during fetal development.

METHODS

The study was conducted among Polish rural women recruited at the Mogielica Human Ecology Study Site. The participants were 234 women aged 45 to 92 (mean = 60.2; SD = 10.44). The indicators of early-life environment analyzed in the study were: Absolute Finger Ridge Count (AFRC), the difference between mean number of ridge counts in both thumbs and both little fingers (Md15), overall facial fluctuating asymmetry (OFA), central facial asymmetry (CFA), right and left hand 2D:4D.

RESULTS

Values of biomarkers of fetal development did not vary among groups of women born in different seasons of the year.

CONCLUSIONS

Lack of differences in values of biomarkers according to birth season may indicate that: (a) season of birth is not a good indicator of early-life conditions; (b) tested biomarkers do not reliably reflect the prenatal environment; (c) season of birth does not fully overlap with the sensitive periods of biomarker development and thus fails to capture differences in developmental conditions.

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.

Season of birth and subsequent body size: the potential role of prenatal vitamin D

OBJECTIVES

The relationship between season of birth and various physical and psychological outcomes was reported in many studies, although the underlying mechanism still remains unrecognized. The aim of this study was to explore the season-of-birth effect on body size in the sample of 1,148 eight-year-old Polish urban children and propose the mechanism responsible for this effect.

METHODS

The children were examined three times at their birthdays and at two cross-sectional surveys. Effects of the season of birth were checked by fitting the cosine function to empirical values and by comparison between two groups born in different periods of the year.

RESULTS

Data gathered at three examinations led to the same results: season-of-birth effect occurred only in boys and only in those relatively shortly breastfed and/or descended from the families of low-socioeconomic status. Specifically, the individuals born in October-April were taller (by 2-3 cm), heavier (by 2-3 kg), and fatter than those born in May-September.

CONCLUSIONS

The following explanatory mechanism has been formulated: insolation in Poland is minimal in November-February (winter period), and so ultraviolet absorption and vitamin D production is then the lowest. Vitamin D regulates embryo's cellular differentiation, and its deficiency triggers permanent developmental changes. Therefore, individuals conceived in autumn (i) are at the greatest risk of early vitamin D deficiency, (ii) are born in summer, and (iii) are relatively small in their further lives. The contribution of low-socioeconomic status, short breastfeeding, and being a male to the occurrence of the season-of-birth effect is also discussed.

Association of birth weight and length with air temperature, sunlight, humidity and rainfall in the city of Warsaw, Poland

Several studies have shown the month of birth effect on birth weight and height of children. The mechanism of this phenomenon is not fully explained. Using data from Warsaw hospitals, the influence of four climatic factors (temperature, sunlight, humidity and rainfall) on birth outcomes was studied. The sample consisted of 10,631 neonates (5450 boys and 5181 girls) born between May 2004 and April 2005. Individual values for birth weight and length were standardised on the overall mean and standard deviation for all subjects, separately for each sex. Differences in means of Z-score birth outcomes between months, seasons and semi-annual periods of birth were assessed by one-way analysis of variance, separately for each sex. The relation between average values of four atmospheric factors and average neonatal outcomes for each month of birth was assessed by a weighted Spearman rank correlation. The results revealed significant differences in average Z-scores of neonate weight and length between months of birth for boys and girls. Significant seasonal variation in Z-scores means was only found for birth length in boys. The correlation between four atmospheric factors during pregnancy and birth length was the highest for boys and occurred in the second trimester. Second trimester of fetal growth is the period most sensitive to influences of climatic factors.