Development of birthweight and length for gestational age and sex references in Yucatan, Mexico.

OBJECTIVE: To develop sex- and gestational age specific reference percentiles and curves for birth weight and length for Yucatec neonates using data from birth registers of infants born during 2015-2019. MATERIAL AND METHODS: Observational, descriptive, epidemiologic study in a 5-year period including every registered birth in the state of Yucatan, Mexico using birth registries. A total of 158 432 live, physically healthy singletons (76 442 females and 81 990 males) between 25 and 42 weeks of gestation were included in the analysis. We used the LMS method to construct smoothed reference centiles (3rd, 10th, 25th, 50th, 75th, 95th, and 97th) and curves for males and females separately. RESULTS: Mean maternal age was 26 (SD = 6.22) years. Fifty-two percent of births occurred by vaginal delivery, 37% were firstborn and similar proportions were second (33%) and third or more (30%) born. 5.5% of newborns included in the references corresponds to neonates born before 37 weeks of gestation (5.9% boys and 5.1% girls). In both sexes, the percentage of infants with a birthweight less than 2500 g was 6.7%. The birthweight at the 50th percentile for males and females at 40 weeks of gestation in this cohort was 3256 and 3167 g, respectively, and the corresponding values for birth length were 50.23 and 49.84 cm (mean differences between sexes: 89 g and 0.40 cm, respectively). CONCLUSION: The reference percentile and curves developed in this study are useful for research purposes and can help health practitioners to assess the biological status of infants born in Yucatán.

The relationship between pre-pregnancy BMI and energy and macronutrients intakes during pregnancy in women from Yucatan, Mexico.

In this observational study, our aim was to analyse the association between pre-pregnancy BMI and adequacy rates of energy and macronutrient intakes in a sample of pregnant women from Yucatan, Mexico. From September to December 2019, we collected data on socioeconomic, pregnancy, and dietary characteristics, and took anthropometric measurements of women during household visits. Pre-pregnancy BMI was calculated from measured height and self-reported body weight. Energy and macronutrient intakes (obtained from three 24-h dietary recalls) were compared with the estimated trimester-specific requirements to calculate adequacies (%). Multiple linear regression models showed that after accounting for maternal socioeconomic characteristics and perinatal variables, each unit increase in pre-pregnancy BMI was associated with decreases of 2%, 2%, and 2.6% in energy, carbohydrate, and total fat intakes, respectively. These results were significant when under- and over-reporters were excluded from the analyses. Women who enter pregnancy with higher BMI values may voluntarily or involuntarily reduce their food intake.IMPACT STATEMENTWhat is already know about this subject? Some studies have analysed the relationship between pre-pregnancy BMI categories (normal weight, overweight, and obesity) and diet quality during pregnancy, but few studies have focussed on quantitative energy and macronutrient intakes or their adequacies in relation to pre-pregnancy BMI.What do the results of this study contribute? In this sample of Mexican women belonging to a middle socioeconomic status, we found that after excluding under- and over-reporters from the analyses and accounting for maternal socioeconomic characteristics and perinatal variables, BMI was negatively associated with adequacy intake rates of energy, carbohydrates, and total fats during pregnancy.What are the implications of these findings for clinical practice and/or further research? Women who enter pregnancy with higher BMI values may voluntarily or involuntarily reduce their food intake. These results can be used to accordingly plan diet counselling during pregnancy.

Birth weight and body composition in 6-to-8 years old Maya children.

OBJECTIVE: To test the hypothesis that fetal growth, indexed by birth weight (BW), induce metabolic adjustments in the fetus that will be reflected in differences in body composition in a sample of 6-to 8-years old urban Maya children from Yucatan, Mexico. METHODS: We measured height (cm), weight (kg) and triceps skinfold (mm) in 260 children (boys: 132, girls: 128), and height (cm) and weight (kg) in their mothers. Body composition was estimated in children through bioelectrical impedance analysis. Outcome variables were fat free-mass index (FFMI = fat-free mass [kg]/height [m]2 ) and fat mass index (FMI = fat mass [kg]/height [m]2 ). The main independent variable was BW z-scores. Multiple linear regression models were used to analyze the association between BW z-scores and outcome variables measured during childhood. Separate analyses were done for boys and girls. Complementary models were run using outcomes as z-scores. Models were adjusted for location, children's and mothers' age, mother's body mass index and household overcrowding index. RESULTS: BW in boys was positively associated with FFMI and FMI. FFMI increase 0.34 kg/m2 per 1-SD increase in BW and FMI increase 0.40 kg/m2 per 1-SD increase in BW. When outcomes were used as z-scores, FFMI increase 0.24 SD and FMI increase 0.18 SD per 1-SD increase in BW, respectively. CONCLUSION: Our results are in contrast with previous findings that birth weight is more consistently associated with subsequent lean mass than with fat mass. Associations, detected only in boys, may be explained by sex differences in sensitivity to early life environments.

The timing of adrenarche in Maya girls, Merida, Mexico.

BACKGROUND: Adrenarche involves maturation of the hypothalamic-pituitary-adrenal axis and increased production of dehydroepiandrosterone and its sulfate ester, dehydroepiandrosterone-sulfate (DHEA-S). It occurs at ages 6 to 8 in industrialized populations, marking the transition from childhood to juvenility and cognitive development at middle childhood. Studies in subsistence level populations indicate a later age (8-9) for adrenarche, but only two such studies currently exist for comparison. AIMS: To investigate adrenarcheal age among Maya girls and its association with body composition and dietary variables. We hypothesized adrenarche would occur earlier given the current dual burden of nutrition in Mexico. MATERIALS AND METHODS: 25 Maya girls aged 7 to 9 from Merida, Mexico using ELISAs to measure salivary DHEA-S, standard anthropometry for height, weight, and skinfolds, bioelectrical impedance for body composition variables, as well as a food frequency questionnaire for dietary information. RESULTS: Our hypothesis was rejected-adrenarche occurred close to 9 years. While no measures of body composition were significantly associated with adrenarcheal status, girls eating meat and dairy products more frequently had significantly higher DHEA-S levels. DISCUSSION: Like other populations living in ecologically challenging environments, adrenarche occurred relatively late among Maya girls. Adrenarche has been linked to measures of body composition, particularly, the adiposity or body mass index rebound, but no relevant anthropometric measures were associated, possibly because of the small sample. CONCLUSION: Further studies are required to illuminate how adrenarcheal variation relates to developmental plasticity, body composition, pubertal progression, and animal product consumption in other transitional populations.

Birth weight, birth order, and age at first solid food introduction influence child growth and body composition in 6- to 8-year-old Maya children: The importance of the first 1000 days of life.

OBJECTIVES: To analyze the relationship of birth weight, birth order, breastfeeding duration, and age of introduction of solid foods with height, fat mass, and fat-free mass in a sample of Maya children when aged 6 to 8 years old. METHODS: We collected data on anthropometry, body composition, children's birth weight, birth order, early feeding practices, and household socioeconomic characteristics in a sample of 260 Maya children aged 6 to 8 years living in Merida and Motul, two cities in Yucatan, Mexico. Multiple regression models were performed to identify variables associated with height-for-age (HAZ), fat mass index (FMI), and fat-free mass index (FFMI). The predictors included in the models were birth weight (kg), birth order, duration of breastfeeding (months), age at introduction of solid foods (months), maternal age (years), and height (cm). Models were adjusted for the influence of children's age and sex, maternal educational level, and household overcrowding. RESULTS: HAZ was positively associated with child birthweight and maternal height and age, but inversely associated with birth order and age of introduction of solid foods. FMI was positively associated with birth weight, maternal age, and height, and negatively associated with birth order. FFMI was positively associated with maternal age and birth weight. CONCLUSIONS: These results are evidence of the importance of the first 1000 days of life for the growth and body composition of Maya children and contributed to understand the development of nutritional dual burden in this population.

Caesarean birth and adiposity parameters in 6- to 8-year-old urban Maya children from two cities of Yucatan, Mexico.

OBJECTIVES: The purpose of this study was to analyze the association between birth mode and fat mass index (FMI = fat mass [kg]/height [m]2 ), and z-score values of waist circumference (WCZ) and sum of triceps and subscapular skinfolds (SumSkfZ) in a sample of 256 6- to 8-year-old urban Maya children from the cities of Merida and Motul in Yucatan, Mexico. METHODS: From September 2011 to January 2014, we measured height, weight, waist circumference and skinfolds in children, and height and weight in their mothers. Body composition was estimated in both generations through bioelectrical impedance analysis. Data on children's birth mode and birth weight were obtained from birth certificates. A pre-validated questionnaire for mothers was used regarding household living conditions. Multiple regression models were used to analyze the association between birth mode and adiposity parameters, adjusting for the effect of place of residence, household crowding index, children's birth weight, and maternal fat mass. Separate regression models were run for boys and girls. RESULTS: Caesarean-born children comprised 43% of the entire sample. Caesarean section (CS) was found to be associated with higher values of body adiposity in girls, but not in boys. Specifically, our models predicted that girls born by CS had an increased value of 0.817 kg/m2 in FMI and showed higher SDs values for WCZ and SumskfZ (0.29 and 0.32 SD, respectively) than girls who were delivered vaginally. DISCUSSION: Our results support the hypothesis that CS is associated with increased levels of adiposity in childhood, but only in girls.

Body proportionality and adiposity are not related in 6- to 8-year-old Yucatec Maya children.

OBJECTIVE: The aim of this study was to analyze the association between relative leg length (RLL) (leg length × 100/height) and adiposity in a sample of 6- to 8-year-old children of Maya ancestry from Motul and Merida, Mexico. METHODS: This cross-sectional study included 260 children (128 girls) measured between 2011 and 2015. The RLL was used as a measure of body proportionality. Linear regression models were performed to examine the association between RLL (predictor) and three adiposity indicators (outcome variables): fat mass index (kg/m2 ), waist circumference (z-score), and sum of triceps and subscapular skinfolds (z-score). RESULTS: The prevalence of stunting was 12%, and a higher prevalence (19%) of short RLL (leg stunting) was found. The prevalence of overweight and obesity were 16% and 20%, respectively, but the highest prevalence was found for abdominal obesity (40%). None of the adiposity indicators were related to RLL (P > .05), even after adjusting for the influence of children's sex and age. CONCLUSIONS: Our results suggest that the coexistence of short RLL and high body adiposity is not observed in all populations. Our findings do not discount the possibility that a negative association between RLL and adiposity is expressed at older ages.

Living conditions and change in age of menarche in adult Maya mothers and daughters from Yucatan, Mexico.

OBJECTIVES: To analyze whether living conditions, experienced by mothers and adult daughters during their childhood, are associated with age at menarche (AAM) in daughters. METHODS: From September, 2011, to January, 2014, AAM and childhood living conditions were collected from a sample of 246 dyads of Maya mothers (mean age = 59.60 years, SD = 8.64) and their adult daughters (mean age = 33.03 years, SD = 5.57) from the cities of Merida and Motul in Yucatan, Mexico. Indicators of childhood living conditions were number of siblings and quality of house construction materials in both generations, and father's absence among daughters in their pre-menarcheal years. Multiple regression models were used to assess the association between childhood conditions in mother-daughter dyads and daughter's AAM. RESULTS: The recalled mean AAM of adult Maya daughters was 12.05 years (SD = 1.53). After adjusting for the influence of mothers' AAM, number of siblings in both the mothers' and daughters' families directly predicted daughters' AAM (more siblings was associated with a later AAM); and a higher (better) index of household conditions in mothers' childhood was associated with earlier AAM in daughters. The household conditions index during the childhood of daughters and father's absence were not associated with their AAM. CONCLUSIONS: Our results suggest that better living conditions experienced by the mothers and daughters during their childhood may lower mean AAM in daughters in the context of populations that show important intergenerational changes in their social and economic conditions.

Maternal height and its relationship to offspring birth weight and adiposity in 6- to 10-year-old Maya children from poor neighborhoods in Merida, Yucatan.

OBJECTIVE: To analyze the relationship between maternal height, offspring birth weight, and adiposity at 6-10 years of age in a sample of 197 mother-child dyads from Merida, Mexico. MATERIALS AND METHODS: During 2008-2009 and 2011-2013, measurements were taken of maternal height and weight; and height, waist circumference (WC), and skinfolds (triceps, subscapular, and suprailiac) of their children. Participant body composition was estimated using a bioelectrical impedance analyzer. A questionnaire was applied to document household socioeconomic conditions. Multiple linear regression models were used to study the association between maternal height, offspring birth weight and fat mass index (FMI), WC, and sum of skinfolds (SumSkfZ) in boys and girls, separately. RESULTS: After adjusting for child age and household socioeconomic conditions, maternal height was identified to be significantly associated (p < .05) with FMI, WC, and SumSkf only in boys. In all models, child adiposity was inversely related to maternal height. Offspring birth weight was not associated with any adiposity parameter. DISCUSSION: The results suggest that maternal nutritional history as reflected in short maternal stature is associated with higher body fat in children, and that male offspring are more vulnerable to intergenerational influences.

ETHNICITY AND INCOME IMPACT ON BMI AND STATURE OF SCHOOL CHILDREN LIVING IN URBAN SOUTHERN MEXICO.

Obesity affects quality of life and increases the risk of morbidity and mortality. Mexico, a middle-income country, has a high prevalence of overweight and obesity among urban children. Merida is the most populated and growing city in southern Mexico with a mixed Mayan and non-Maya population. Local urbanization and access to industrialized foods have impacted the eating habits and physical activity of children, increasing the risk of overweight and obesity. This study aimed to contribute to the existing literature on the global prevalence of overweight and obesity and examined the association of parental income, ethnicity and nutritional status with body mass index (BMI) and height in primary school children in Merida. The heights and weights of 3243 children aged 6-12 from sixteen randomly selected schools in the city were collected between April and December 2012. Multinomial logistic regression models were used to examine differences in the prevalence of BMI and height categories (based on WHO reference values) by ethnicity and income levels. Of the total students, 1648 (50.9%) were overweight or obese. Stunting was found in 227 children (7%), while 755 (23.3%) were defined as having short stature. Combined stunting and overweight/obesity was found in 301 students (9.3%) and twelve (0.4%) were classified as stunted and of low weight. Having two Mayan surnames was inversely associated with having adequate height (OR=0.69, p<0.05) and the presence of two Maya surnames in children increased the odds of short stature and stunting. Children from lower income families had twice the odds of being stunted and obese. Overweight, obesity and short stature were frequent among the studied children. A significant proportion of Meridan children could face an increased risk of developing cardiovascular disease and its associated negative economic and social outcomes unless healthier habits are adopted. Action is needed to reduce the prevalence of obesity among southern Mexican families of all ethnic groups, particularly those of lower income.

Intergenerational changes in knee height among Maya mothers and their adult daughters from Merida, Mexico.

OBJECTIVES: To analyze differences in knee height (KH) between adult Maya mothers and daughters in Merida City, Mexico, and determine if these differences are associated with their childhood socioeconomic conditions. METHODS: From September 2011 to January 2014, we measured KH and collected data on childhood conditions (place of birth, type of drinking water, family size, and fathers' occupation) from a sample of 180 Maya mother-daughter dyads. Mean KH intergenerational difference was calculated and compared for each category of socioeconomic variables and a multiple regression model was used to assess the association between childhood conditions and KH difference. RESULTS: A relative increase of 1.05 cm (SD = 2.3 cm) or 0.45 standard deviations (effect size of difference) was observed in KH between generations. Place of birth was significantly associated with KH. With three other variables statistically adjusted for, the intergenerational KH difference was 1.5 cm greater when mothers were born outside Merida but daughters were born in the city. Piped water consumption by mother-daughter dyads was associated with 1.5 cm of increase in KH difference compared with dyads who consumed well water (P = 0.058). CONCLUSIONS: The relative increase in KH between mothers and daughters represents a portion of the expected change in growth in a group that has experienced few substantial improvements in their living conditions. Some improvements in childhood living conditions resulting from the intergenerational transition from rural to urban environments seem to be linked to a modest, but statistically significant intergenerational increase in KH among Maya women in Merida.

Intergenerational influences on the growth of Maya children: The effect of living conditions experienced by mothers and maternal grandmothers during their childhood.

OBJECTIVES: To test the hypothesis that living conditions experienced by maternal grandmothers (F1 generation) and mothers (F2 generation) during their childhood are related to height and leg length (LL: height - sitting height) of their 6-to-8 year old children (F3 generation). METHODS: From September 2011 to June 2012 we obtained height and LL, and calculated z-score values of these measurements for 109 triads (F1 , F2 , F3 ) who are Maya living in Merida, Yucatan, Mexico. Multiple regression models were adjusted to examine the relation of anthropometric and intergenerational socioeconomic parameters of F1 (house index and family size during childhood) and F2 (paternal job loss during childhood) with the z-score values of height and LL of F3 . RESULTS: Children's height and LL were positively associated with maternal height and LL. This association was relatively stronger in LL. Better categories of grand-maternal house index were significantly associated with higher values of height and LL in grandchildren. Grand-maternal family size was positively related with LL, but not with height. CONCLUSIONS: Our findings partially support the hypothesis that living conditions experienced by recent maternal ancestors (F1 and F2 ) during their growth period influence the growth of descendants (F3 ). Results suggest that LL is more sensitive to intergenerational influences than is total height and that the transition from a traditional rural lifestyle to urban conditions results in new exposures for risk in human physical growth.

Height Growth and Percentage of Body Fat in Relation to Early Menarche in Girls from Merida, Yucatan, Mexico.

Early menarche (EM) (i.e., age at menarche [AAM] <12 years of age) is related to short height and higher body fatness. In a mixed-longitudinal study done in Merida, Yucatan, height, body mass index (BMI), and percentage of body fat (BF%) were recorded at a one-year interval among 258 postmenarcheal (EM = 94) girls. Anthropometric measurements were recorded of the age cohorts in 2008-09 when participants were 13-17 years of age (baseline), and in the one-year follow-up study (± 6 days) the girls were 14-18 years of age. The BF% was estimated through bioelectrical impedance analysis. Mean AAM was 10.59 years in EM girls and 12.54 years in not early menarche (NEM) girls. Height growth (cm/year) was greater in NEM girls. Mean values of BMI, BF%, and frequencies of stunting (low height-for-age) and excess weight (overweight + obesity) were higher in EM girls than in their NEM age peers.

Maternal short stature does not predict their children's fatness indicators in a nutritional dual-burden sample of urban Mexican Maya.

The co-existence of very short stature due to poor chronic environment in early life and obesity is becoming a public health concern in rapidly transitioning populations with high levels of poverty. Individuals who have very short stature seem to be at an increased risk of obesity in times of relative caloric abundance. Increasing evidence shows that an individual is influenced by exposures in previous generations. This study assesses whether maternal poor early life environment predicts her child's adiposity using cross sectional design on Maya schoolchildren aged 7-9 and their mothers (n = 57 pairs). We compared maternal chronic early life environment (stature) with her child's adiposity (body mass index [BMI] z-score, waist circumference z-score, and percentage body fat) using multiple linear regression, controlling for the child's own environmental exposures (household sanitation and maternal parity). The research was performed in the south of Merida, Yucatan, Mexico, a low socioeconomic urban area in an upper middle income country. The Maya mothers were very short, with a mean stature of 147 cm. The children had fairly high adiposity levels, with BMI and waist circumference z-scores above the reference median. Maternal stature did not significantly predict any child adiposity indicator. There does not appear to be an intergenerational component of maternal early life chronic under-nutrition on her child's obesity risk within this free living population living in poverty. These results suggest that the co-existence of very short stature and obesity appears to be primarily due to exposures and experiences within a generation rather than across generations.

Body fatness in relation to physical activity and selected socioeconomic parameters of adolescents aged 15-17 years in Merida, Yucatan.

BACKGROUND: Increasing rates of overweight and obesity in adolescents are major concerns in many countries, including Mexico. OBJECTIVES: To study anthropometric and body composition characteristics (BCC) and their relations with socioeconomic status (SES), biological history and physical activity (PA) of school-going adolescent boys and girls in the city of Merida, Yucatan, Mexico. SUBJECTS AND METHODS: In this cross-sectional study, a sample of 321 adolescents (156 boys and 165 girls) aged 15-17 years from public and private schools in Merida, was taken from a study carried out in 2008-2009. RESULTS: Body mass index had significant correlations to BCC (fat mass and fat-free mass). The rate of stunting was higher in girls (18.20%) than in boys (7.69%). Stunted adolescents had higher body fat (%) than normally growing peers. High rates of overweight (boys 26.28%, girls 24.24%) and obesity (boys 10.26%, girls 6.06%) were recorded. SES (parents' age, education and occupation; crowding index in the family; household food expenditure), participants' biological history and PA are related with height and BCC by age and sex. CONCLUSION: Adolescents with excess weight (overweight + obesity) reported being less physically active. SES and PA were strongly related to growth and body fatness in the studied adolescents.

Height, weight and body mass index by age and sex in children aged 4 to 6 years in Merida, Mexico, as compared to international references after normalization with LMS.

A cross-sectional study was done in 2006-2007 of 458 children (218 boys and 240 girls) aged 4 to 6 years (range 4.00 to 6.99 years) in Merida, Mexico. Height (cm) and body weight (kg) were measured to estimate growth; body mass index (BMI, kg/m2) was calculated to evaluate nutritional status. Results showed significant sex difference with respect to height, weight, and BMI. Increment of height and weight with age was observed. However, age difference in BMI was not consis- tent. Nutritional status was evaluated using International Obesity Task Force (IOTF) classification and BMI cut-off values showed notable rates of overweight (boys 14.41% and girls 17.75%) and obesity (boys 12.43% and girls 7.21%). Anthropometric data of height, weight, and BMI were normalized using LMS methodology and were compared with World Health Organization (WHO) growth reference data. Again, increment of height and weight with age was observed although those were lower in the present study for boys and girls than the corresponding WHO growth reference data. In contrast, mean BMI by age in the present results exceeded WHO reference data, especially above the 85th percentile. Assessment of nutritional status with reference to IOTF and WHO revealed similar trends.

Nutritional status of Maya children, their mothers, and their grandmothers residing in the City of Merida, Mexico: revisiting the leg-length hypothesis.

OBJECTIVES: To test the hypothesis that leg length-relative-to-stature is a more sensitive indicator of nutrition and health than is total height (HT) or sitting height (SH) in a sample of 109 triads of urban Maya children (6.0-8.99 years), their mothers, and maternal grandmothers from Merida, Mexico. METHODS: From September 2011 to June 2012, the following factors were obtained from all participants: (1) HT, SH, and leg length (LL); (2) the sitting height ratio (SHR = [SH × 100]/HT), relative leg length index (RLLI = [LL × 100]/height), and percentiles and z-scores of HT, SH, and LL were calculated; and (3) the percentages of stunting for children or very short ZHT for the adults, short ZSH, and short ZLL: HT-for-age, SH-for-age, or LL-for-age below the 5th percentile of the reference were calculated. Correlations were performed to examine the association between z-scores of HT, SH, and LL among three generations. RESULTS: Stunting in children was 11% (short ZLL = 29%, short ZSH = 7%). Short ZHT was present in 71% of mothers (short ZLL = 54%, short ZSH = 50%) and 90% of grandmothers (short ZLL = 69%, short ZSH = 83%). Significant correlations in ZHT, ZSH, and ZLL were found in mother-to-child and grandmother-to-mother, with the strongest correlations for ZLL. CONCLUSIONS: These findings support the hypothesis for children and mothers. Based on ZLL, there is evidence that childhood and nutrition have improved somewhat for each younger generation. Persistent environmental adversity during growth resulted in growth deficits for LL and SH for the mothers and grandmothers.

Effects of Maya ancestry and environmental variables on knee height and body proportionality in growing individuals in Merida, Yucatan.

OBJECTIVE: Identify the biological, social, and economic conditions influencing the knee height/stature index (KHSI) in growing individuals of Maya ancestry in the city of Merida, Yucatan, Mexico. METHODS: The hypothesis was that KHSI values would be lower in subjects with two Maya surnames. This was tested by analyzing the effect of a series of environmental, biological, and socioeconomic variables on stature and knee height (KH). Data were collected from 2008 to 2009 from 841 individuals (444 girls), 9 to 17 years of age, in Merida, Yucatan, Mexico. Ancestry was used as a proxy for genetics, and based on number of Maya surnames (2, 1, or none). The KHSI was calculated for all individuals. Multiple regression models were run to identify the variables that best explained variation in stature, KH, and KHSI. RESULTS: Ancestry negatively (P < 0.05) affected stature, but birth weight, crowding index, and mother's education level (MEL) were more significant (P < 0.01). Ancestry had no effect on KH and KHSI values, but birth weight and MEL had a significant effect. Individuals who had grown up in an adverse environment, in terms of MEL, had higher KHSI values. Apparently, lower leg length was proportionally longer than thigh length in the sample. CONCLUSIONS: Growth measurements were more responsive to the studied environmental variables than to ancestry-related genetic conditions. Genetic predisposition is, therefore, not the primary cause of short stature in this sample of Yucatec Mayas.

Variation in height and knee height in adolescents in Merida, Mexico, by head of household employment level and family income.

Variation in height among young adults has been linked to the living conditions of different social groups. The aim of this study was to measure variation in the height and knee height of young adults by head of household employment level and family income. The sample comprised 180 individuals (90 girls) aged 16 and 17 years living in the city of Merida, Mexico. Height and knee height were measured by anthropometry, and individuals' family social and economic data collected from their mothers. Variation in these measurements was analysed by three categories of employment and family income terciles. One-way ANOVAs were done by sex to compare mean height and knee height by employment and family income. Coefficients of variation were calculated and a Bartlett test applied. Significant differences in height and knee height were observed only between family income terciles. Both sexes were taller at the highest levels of family income (p<0.05) and men had the highest (p<0.05) knee height. Highest family income individuals exhibited the least variation in height and knee height. Similarity in socioeconomic conditions for families in the lowest family income tercile and with employee heads of household was not associated with lower variation of height and knee height.

Dietetic characteristics of a sample of Mayan dual burden households in Merida, Yucatan, Mexico.

The Maya are the most populous and shortest in stature Native American ethnic group. The Maya provide us a good opportunity to study the dietetic characteristics of a group who experience nutritional dual burden (the combination of under and ovenutrition) at the individual, mother-child dyad and population level. The aim of this study is to describe general dietetic patterns of a sample of Maya mothers and children who experienced nutritional dual burden and were living in the city of Merida, Yucatan, Mexico. From February to July 2010 we applied food frequency questionnaires (FFQ) to 58 dyads of Maya mothers and their children (7-9 years old). The FFQ was developed by staff of the Department of Human Ecology at Cinvestav and included 78 foods, grouped in: cereals and tubers, foods of animal origin, leguminous vegetables, fats, fruits, vegetables, sugars, and daily products. The frequencies of consumption were classified in four levels: 1) no consumption, 2) low (1-2 days/week), 3) medium (3-4 days/week), high (5-7 days/week). The observed pattern suggests a low consumption of fruits and vegetables, a medium consumption of pork, eggs, oil and lard, and a high consumption of soda and whole milk. From these frequencies we extrapolated that the dietetic pattern is characterized by a low intake of fibre and micronutrients and high intake of fat and sugars, findings supported by previous National and regional studies. Our observations suggest that the studied group have a dietetic pattern that has moved away from a traditional Maya diet.