Age of menarche in Oaxaca,Mexico, schoolgirls,with comparative data for other areas of Mexico

Status quo menarcheal information was collected for a mixed urban colonia and rural sample of 315 girls in the Valley of Oaxaca, Mexico. Comparative status quo data for girls from four major urban centres in Mexico and for a rural sample were also analysed. Median age at menarche (estimated by probit analysis) for Oaxaca girls was 14·27±0·20 years, about 0·5 year later than that for the rural sample from Tampico-Altamira, Tamaulipas (13·79±0·20 years), and approximately 1·5 years later than that for girls from the four urban centres in Mexico (12·55±0·10, 12·61±0·08, 12·75±0·10, 12·76±0·07 years). The timing of menarche in Oaxaca girls is similar to that for rural Mayans in Guatemala. Ages at menarche for urban Mexican girls are somewhat lower than those for girls of North-west European ancestry and of North American girls of European ancestry.     

Age at menarche of schoolgirls in Maputo,Mozambique

Age at menarche was analysed in 753 Mozambican schoolgirls taking part in across-sectional anthropometric study in Maputo, Mozambique, in 2000. The probit analysis of the status quo data yielded an median age at menarche of 13.20 +/- 1.18 years. The retrospective method was applied only to recall data of the 396 post-menarcheal girls and it yielded an average of 13.91 +/- 1.29 years. Mean age at menarche in girls living in the urban centre of Maputo was 13.35 and 12.96 years, for recall age and probit analysis, respectively, and 14.51 and 13.68 years for girls living in the slums surrounding the centre. The differences in age at menarche, calculated by recall method, between girls from central Maputo and girls from the slums were statistically significant (p = 0.000). Parent's educational level also revealed a significant effect on age at menarche. Girls whose parents had a lower educational level showed a later age at menarche. For the size of the family, girls who were later borne had a higher age at menarche. In the 1960s, the age at menarche was 13.55 and 13.83 years in urban and rural girls, respectively. In this study, we found a lack of decrease in the mean age at menarche (13.9 years), which could be due to the poor living conditions in Mozambique between 1960 and 2000 as a result of the civil war from 1976 to 1990. Despite the economic growth of the country in the last decade, Mozambique is still in the group of the poorest countries in the world; in spite of this fact, the mean menarcheal age in these girls are amongst the lowest values presented for African countries.     

Age at menarche of European, Afro-Caribbean and Indo-Pakistani schoolgirls living in London

Age at menarche is reported for 1,365 European, 530 Afro-Caribbean and 282 Indo-Pakistani schoolgirls taking part in a cross-sectional anthropometric survey in the London Area Health Authorities of Kensington, Chelsea and Westminster, and Brent and Harrow, in 1980-81. Mean ages at menarche are 13.59 +/- 0.37 years (European), 13.18 +/- 0.11 years (Afro-Caribbean) and 13.06 +/- 0.20 years (Indo-Pakistani). The European value is significantly higher than those for Afro-Caribbean and Indo-Pakistani girls, and for Europeans living in the same areas of London in 1966. Social class has an effect on age at menarche in Afro-Caribbean and European girls, but not Indo-Pakistani girls, whilst family size has an effect on age at menarche in Europeans and Indo-Pakistanis.     

Secular change in age at menarche in rural Oaxaca, southern Mexico: 1968--2000

OBJECTIVE: To evaluate secular change in the age at menarche between 1978 and 2000 in residents of a rural Zapotec-speaking community in Oaxaca, southern Mexico, using status quo and retrospective methods. MATERIALS AND METHODS: Status quo menarcheal status of girls 9-18 years of age in 1978 (n= 101) and 2000 (n=238) and retrospective ages at menarche of adult women 19+ years of age in 1978 (n = 228) and 2000 (n = 246) were obtained via interview. Probit analysis was used to estimate median ages at menarche and 95% confidence intervals (CI) for the status quo data. Analysis of variance and linear regression was used to compare the retrospective data across surveys. RESULTS: The median ages at menarche of adolescents are 14.8+/-1.2 years (0.24 year, 95% CI 14.2-15.4 years) in 1978 and 13.0+/-1.0 years (0.10 year, 95% CI 12.7-13.3 years) in 2000. Age at menarche has declined by 1.8 years over about 23 years, 0.78 year/decade (95% CI = 0.65-0.91 year/decade). Recalled ages at menarche do not differ by age group in the 1978 survey, but differ significantly by age group in the 2000 survey (p <0.001). Within the 2000 survey, the two youngest age groups (< 29, 30-39 years) do not differ, but attain menarche earlier than women in the four older age groups (p < 0.05), who do not differ from each other in age at menarche. The estimated rates of secular decline in age at menarche in adult women vary between 0.38 and 0.42 years/decade (0.26-0.56 year/decade). CONCLUSIONS: There is a major secular decline in the age at menarche of adolescent girls and young adult women between 1978 and 2000. The estimated rate of decline in adult women is about one-half of that in adolescent girls. The secular decline in age at menarche is consistent with corresponding secular gains height, sitting height and estimated leg length of children and adolescents in the community; corresponding secular gains are smaller in young adults 19-29 years.     

Genetic diversity of HLA system in two populations from Oaxaca,Mexico: Oaxaca city and rural Oaxaca

We studied HLA class I (HLA-A, -B) and class II (HLA-DRB1, -DQB1) alleles by PCR-SSP based typing in 636 Mexicans from the state of Oaxaca living in the city of Oaxaca (N = 151) and rural communities (N = 485), to obtain information regarding allelic and haplotypic frequencies. We found that the 13 most frequent haplotypes in Oaxaca are all of putative Native American origin. Admixture estimates revealed that the main genetic components in the state of Oaxaca are Native American (73.12 ± 2.77% by ML; 61.52% of Native American haplotypes) and European (17.36 ± 2.07% by ML; 20.69% of European haplotypes), and a relatively high African genetic component (9.52 ± 0.88% by ML; 8.94% of African haplotypes).     

Dengue 2 genotypes in the state of Oaxaca, Mexico

Summary. To genetically characterize dengue 2 (DEN-2) viruses in Oaxaca, Mexico, the C protein, and a portion of the prM protein genes of 8 isolates from the 2001 DEN epidemic were sequenced. The sequences were compared to those of prototype DEN-2 viruses from various parts of the world. Phylogenetic analysis suggested that the 2001 isolates of DEN-2 were of the American/Asian genotype and were most similar to the Jamaica and Venezuelan isolates MARA3, LARD1996 and LARD1910. Molecular analyses confirmed the origin of the isolates. This study indicates that DEN-2 strains of American/Asian genotype probably from Southeast Asian are circulating in Oaxaca.     

Monthly distribution of menarche among schoolgirls from a municipality in Southeastern Brazil

We studied the monthly distribution of menarche among schoolgirls from Barrinha, Brazil, a municipality of rural characteristics in the process of transition to urbanization, economically dependent on sugar cane culture and processing. The association between season of the year, month of the year, and birth month and the occurrence of menarche was evaluated. The schoolgirls who provided the date of menarche (month and year) by the recall method and who had menarche up to 36 months before the interview were selected for analysis (460 girls). The correlations between month of occurrence of menarche and month of birth and between menarche and seasons of the year were determined by the chi‐square test and the mean monthly ages at menarche were compared by Student's t‐test, with a significance level of 0.05. There was a correlation between month of birth and month at menarche, with a peak of occurrence of menarche in December not affected by the menstruating patterns of maturation, but no correlation between menarche and seasons of the year. The difference between mean age at menarche in December (spring–summer transition) and in June (autumn–winter transition) was not significant. Mean age at menarche during the month following school vacations was lower. We conclude that situations of stress–relaxation transition, such as end of the school year, beginning of school vacation, and, perhaps most important, the socioeconomic factor—the end of the sugar cane harvest, when rural workers receive their final payments—favor the occurrence of the peak of menarche in December. Am. J. Hum. Biol. 16:17–23, 2004. © 2003 Wiley‐Liss, Inc.     

Age at menarche in northwest Indian females and a review of Indian data

Data on menarcheal age were collected by a status quo method on a sample of 709 girls drawn from an urban Punjabi population of Chandigarh. Probit analysis provided a median age at menarche of 13.2 +/- 0.04 years with a standard deviation of 1.09. Menarche occurred in all cases between 10 and 16 years. Comparison with other Indian populations shows that populations at higher altitude and in peninsular India have a later maturation than the present sample.     

Prevalence of Antibodies to Onchocerca volvulus in Residents of Oaxaca, Mexico, Treated for 10 Years with Ivermectin

Studies to determine the prevalence of antibodies to Onchocerca volvulus, prior to and after actions carried out to interrupt transmission, are scarce in Mexico. Here we report the prevalence of immunoglobulin G (IgG) and IgG4 antibodies in an enzyme-linked immunosorbent assay (ELISA) against a crude extract of O. volvulus adult worm in serum samples from persons under noninterrupted biannual treatment with ivermectin in areas of onchocercosis endemicity in Mexico. To perform the prevalence studies, the ELISA procedures were first evaluated. Serological studies were performed with serum samples from skin microfilaria carriers from Guatemala and from people microfilariodermic negative living in the same area as the Guatemalan patients. Sensitivity values for IgG or IgG4 detection were 71 and 86%, while specificities were 92 and 100%, respectively. No anti-O. volvulus antibodies were found in samples from nonendemic controls from Mexico, but 3 of 71 samples from residents in the onchocercosis area of Oaxaca, Mexico, and who have been under ivermectin treatment during the last 10 years were only positive to IgG. Notwithstanding that the IgG4 isotype was not detected and a low (4.2%) anti-O. volvulus IgG antibody prevalence was found, a seroepidemiological follow-up must be performed in order to confirm interruption of onchocercosis transmission in the area of Oaxaca, Mexico, in which onchocercosis is endemic.     

Prevalence of antibodies to onchocerca volvulus in residents of Oaxaca, Mexico, treated for 10 years with ivermectin

Studies to determine the prevalence of antibodies to Onchocerca volvulus, prior to and after actions carried out to interrupt transmission, are scarce in Mexico. Here we report the prevalence of immunoglobulin G (IgG) and IgG4 antibodies in an enzyme-linked immunosorbent assay (ELISA) against a crude extract of O. volvulus adult worm in serum samples from persons under noninterrupted biannual treatment with ivermectin in areas of onchocercosis endemicity in Mexico. To perform the prevalence studies, the ELISA procedures were first evaluated. Serological studies were performed with serum samples from skin microfilaria carriers from Guatemala and from people microfilariodermic negative living in the same area as the Guatemalan patients. Sensitivity values for IgG or IgG4 detection were 71 and 86%, while specificities were 92 and 100%, respectively. No anti-O. volvulus antibodies were found in samples from nonendemic controls from Mexico, but 3 of 71 samples from residents in the onchocercosis area of Oaxaca, Mexico, and who have been under ivermectin treatment during the last 10 years were only positive to IgG. Notwithstanding that the IgG4 isotype was not detected and a low (4.2%) anti-O. volvulus IgG antibody prevalence was found, a seroepidemiological follow-up must be performed in order to confirm interruption of onchocercosis transmission in the area of Oaxaca, Mexico, in which onchocercosis is endemic.     

Sibling correlations for growth status in schoolchildren from a rural community in Oaxaca, Mexico

Sibling similarities in several anthropometric dimensions were examined in schoolchildren from a rural, agrarian Zapotec community in the Valley of Oaxaca in southern Mexico. The sample consisted of 44 brother, 44 sister, and 110 unlike-sex sibling pairs. Anthropometric dimensions included weight, height, limb circumferences, triceps skinfold, skeletal lengths, and craniofacial, trunk, and extremity breadths. Environmental effects were controlled using data from a household survey, and were summarized in composite variables. Environmental covariance was suggested in partial correlations of the sibling z-scores. The base 10 log of environmental data and sibling z-scores produced slightly different results. Partial correlations of the log-transformed data resulted in a slight overall decrease in sibling correlations for all pairings. This suggests a genetic-environment interaction, and may offer an explanation for the generally higher sibling correlations observed in non-European populations than in European-derived ones.     

Urban-rural contrasts in the growth status of school children in Oaxaca, Mexico

OBJECTIVES: The growth status of school children resident in an urban colonia and in a rural indigenous community in Oaxaca, southern Mexico, was considered in the context of two objectives, current status and the magnitude of urban-rural differences over a span of about 30 years. Both communities were initially surveyed in 1968 and 1972. MATERIALS AND METHODS: Height, body mass, segment lengths, skeletal breadths, limb circumferences, and subcutaneous fatness were taken on 361 rural (177 boys, 184 girls) and 339 urban (173 boys, 166 girls) school children, aged 6-13 years. Additional variables were derived. RESULTS: Height and body mass were significantly greater in urban compared with rural children. Sitting height, estimated leg length and skeletal breadths on the trunk were also larger in urban than in rural school children, but only the difference in skeletal breadths was significant after age and body size were statistically controlled. Urban and rural children did not consistently differ in skeletal breadths on the extremities and limb circumferences. Subcutaneous fatness was more variable. After controlling for age and body size, rural girls had thicker skinfolds. The magnitude of the urban-rural difference in boys in 2000 was greater for body mass, BMI and triceps skinfold, and reduced for height, sitting height, leg length, and arm and estimated arm muscle circumferences compared with 1970. The magnitude of the urban-rural difference in girls was greater in 2000 than 30 years earlier for body mass, height, sitting height, leg length and BMI. Urban-rural differences for arm and arm muscle circumferences and the triceps skinfold were slightly smaller over the interval. CONCLUSIONS: Children resident in an urban colonia were taller and heavier than children resident in a rural indigenous community. After controlling for age and body size, urban-rural differences in skeletal breadths and limb circumferences were reduced or eliminated, but skinfold thicknesses were greater in rural girls. The magnitude of urban-rural differences in body size has decreased over approximately 30 years in boys, but has increased in girls.     

Age of menarche in urban Argentinian girls

A cross-sectional study in La Plata city, Argentina, yielded a mean age of menarche in 6494 schoolgirls, of 12–53±0–05 years, standard deviation 1–22 years, obtained by probit analysis. These values show a relatively early age of menarche in Argentinian girls as compared to other populations.     

The effect of homozygous sickle cell disease on the age at menarche in Nigerian schoolgirls

Two thousand two hundred and four schoolgirls from four secondary schools in Enugu, the capital of Anambra State in south-eastern Nigeria, were interviewed and provided information regarding their age, menstrual status and the presence or absence of some common chronic disorders. Sickle cell disease was identified and confirmed by haemoglobin electrophoresis in 1.36% of the students. Average age at menarche, determined by probit analysis, was significantly delayed among subjects with sickle cell disease when compared with normal students (14.5 +/- 1.13 years vs. 13.3 +/- 1.09 years; P less than 0.005). Comparison of the average menarcheal age of the normal subjects in this study with previous reports of studies from southern Nigeria confirms a continuing decline of the average age at menarche at a rate of about four months per decade.     

Urban–rural contrasts in the physical fitness of school children in Oaxaca,Mexico

The physical fitness of school children resident in an urban colonia and in a rural indigenous community in Oaxaca, southern Mexico, was compared. Two measures of performance‐related fitness (standing long jump, 35‐yard dash [32 m]) and four measures of health‐related fitness (grip strength, sit and reach, timed sit‐ups, distance run) were taken on 355 rural (175 boys, 184 girls) and 324 urban (163 boys, 161 girls) school children, 6–13 years of age. Urban children were significantly taller and heavier than rural children. Absolute grip strength did not consistently differ between rural and urban children, but when adjusted for age and body size, strength was greater in rural children. Explosive power (standing long jump) and abdominal strength and endurance (timed sit‐ups) were better in urban than in rural children without and with adjustment for age and body size. Urban–rural differences in running speed (dash) and flexibility (sit and reach) varied by age group and sex. Younger rural children and older urban girls performed better in the distance run, whereas older rural and urban boys did not differ in endurance. The size advantage of urban children does not necessarily translate into better levels of performance‐ and health‐related physical fitness. The observed differences may be related to activity habits associated with school physical education and lifestyle in the respective communities. Am. J. Hum. Biol. 15:800–813, 2003. © 2003 Wiley‐Liss, Inc.     

Sibling similarity in annual growth increments in schoolchildren from a rural community in Oaxaca, Mexico

Sibling similarity in annual growth increments was analysed in schoolchildren, aged 6-13 years, from a Zapotec-speaking, subsistence agricultural community in the Valley of Oaxaca in southern Mexico. Sibling correlations for 44 brother-brother, 44 sister-sister, and 110 unlike sex pairs were computed for 17 dimensions holding constant environmental effects, age difference between siblings, and the growth status of each sibling for the dimension. Correlations are negative or close to zero. The lack of similarity between siblings in annual growth increments perhaps reflects age-specific variation in a genotype-environment interaction with chronic undernutrition, the important mediating environmental variable.     

Overweight and obesity in a rural Amerindian population in Oaxaca, Southern Mexico, 1968-2000.

The purpose of this study was to evaluate secular change in the prevalence of overweight and obesity in a rural Zapotec Indian community in southern Mexico between 1968 and 2000. Cross-sectional surveys of children 6-13 years, adolescents 13-17 years, and adults 19 years of age and older resident in a rural community in Oaxaca were conducted in 1968/1971, 1978, and 2000. Individuals present in the 1968, 1978, and 2000 surveys provided a small longitudinal component. Height and weight were measured; the BMI was calculated. International criteria for overweight and obesity were used. Overweight and obesity were virtually absent in school children 6-13 years in 1968 and 1978 and in adolescents in 1978. Small proportions of children (boys, 5%; girls, 8%) and adolescents (boys, 3%; girls, 15%) were overweight in 2000; two children (1%) and no adolescents were obese. Among adults, 7% of males and 19% of females were overweight and <1% of males and 4% of females were obese in 1971/1978, but 46% of males and 47% of females were overweight; and 5% of males and 14% of females were obese in 2000. The trends for children, adolescents, and adults were confirmed in the longitudinal subsamples. In conclusion, overweight and obesity are not presently a major problem in children and adolescents in this rural Zapotec community. Overweight, in particular, and to a lesser extent obesity have increased in prevalence among adults since the late 1970s. The results suggest adulthood as a critical period for onset of overweight and obesity in this sample.