Background The ratio between the length of second and fourth digits (2D/4D) is a putative biomarker for prenatal testosterone and estrogen exposure.Objective The aim of the present study was to examine the association between 2D/4D digit ratio and age at menarche in Algerian women.Methods The study included 111 women with mean age of 26.49 +/- 8.30 years. The 2D/4D was measured directly in both hands using a digital caliper. Multiple linear regression and Mann-Whitney U-tests were used to assess the associations between the digit ratio and the variables studied.Results A total of 111 women reported a mean age at menarche of 12.89 years +/- 1.25. The left-hand digit ratio was negatively related to age at menarche. Statistical analyses revealed a significant negative correlation between the left-hand 2D/4D ratio and age at menarche, suggesting that a more feminine digit ratio is associated with an earlier age at menarche.Conclusions These findings support the evidence for the role of prenatal hormonal influence on reproductive development and contribute to the growing interest in research on digit ratio and female reproductive health. Further studies are needed to confirm these associations in different populations.
ABSTRACT Objectives To assess associations of daytime temperature with reported behavioral heat adaptation and heat‐related symptoms, and to assess whether the temperature–symptom association remained after accounting for behavioral adaptation. Methods A community‐based cross‐sectional study was conducted among 480 women aged 18–49 years from 40 sampling clusters in five districts of Sindh, Pakistan, from April to July 2026. Objective daytime mean temperature was the primary exposure. Behavioral adaptation and heat‐related symptoms were assessed using a structured questionnaire. Multivariable regression models adjusted for age, education, household size, and income, with standard errors clustered at the sampling cluster level. Linear and quadratic temperature specifications were examined. Results Mean daytime temperature was 41.85°C (SD, 1.78; range, 38.2°C–45.9°C). Behavioral adaptation was reported by 58.5% of participants, and at least one heat‐related symptom by 95.8%. Higher temperature was associated with greater odds of behavioral adaptation (OR, 2.28; 95% CI, 1.92–2.70; p < 0.001). The quadratic temperature term indicated attenuation at higher temperatures (OR, 0.91; 95% CI, 0.83–0.99; p = 0.037), with a turning point estimated at 46.2°C, above the observed maximum. Even after controlling for behavioral adaptation, temperature was still linked to heat‐related symptoms (OR, 1.51; 95% CI, 1.12–2.03; p = 0.007). Conclusions Higher daytime temperature was associated with higher reported behavioral adaptation, with a reduction toward the upper end of the observed range. Reported behavioral adaptation remained associated with temperature, while heat‐related symptoms also remained associated with higher tempratures. The cross‐sectional study does not establish a mediating effect.
ABSTRACT Objectives To describe how the secular stature gain was divided between sitting height and leg length across survey intervals and ages, and whether the age at the sitting‐height ratio minimum changed. Methods We designed and conducted four rounds (2005–2020) of the Macao Citizens Physical Fitness Monitoring Survey, a stratified cluster sample of kindergartens and schools, and analyzed 21 919 records of residents aged 3–19 years. Changes were adjusted for age and sex, with standard errors clustered on institution; the age at the ratio minimum was located on penalized‐spline curves, with cluster‐bootstrap intervals. Results Height was 1.97 cm (95% confidence interval [CI] 1.48–2.47) greater in 2020 than in 2005: leg length 0.91 cm (0.66–1.15) and sitting height 1.06 cm (0.77–1.36). Between 2005 and 2010 both segments increased, leg length by more (0.63 cm) than sitting height (0.30 cm), and the ratio fell 0.13 percentage points (−0.19, −0.06); between 2015 and 2020 sitting height rose 0.46 cm, leg length showed no statistically detectable change (0.04 cm; −0.22, 0.30), and the ratio rose 0.13 percentage points (0.04–0.22). Gains were largest at 10–14 years. The age at the ratio minimum did not change detectably (2015 vs. 2005: boys −0.30 years, −0.70 to 0.27; girls −0.93 years, −1.92 to 0.08). Conclusions Across successive survey populations, the stature gain came mainly from the legs in the earliest interval and from sitting height in the latest, without a detectable change in the age at the ratio minimum.
ABSTRACT Introduction Exposure to adverse intrauterine environments resulting from different maternal clinical conditions may alter childhood growth patterns. This study investigated the influence of such environments on body mass index‐for‐age (BMI‐for‐age) trajectories from birth to preschool age. Methods A total of 342 mother–child dyads recruited from three hospitals in southern Brazil were allocated into five groups: diabetes mellitus (DM), systemic arterial hypertension (SAH), maternal smoking, small for gestational age (SGA, used here as a proxy for impaired fetal growth), and a control group. Children were assessed at seven time points from birth to preschool age using anthropometric measurements to calculate BMI‐for‐age z‐scores. Results Generalized estimating equations (GEE) identified a significant interaction between group and time ( p < 0.001). Among girls, at birth, the DM group presented higher BMI‐for‐age z‐scores than the smoking group and reached elevated BMI‐for‐age z‐scores at preschool age, differing from the control group. At 6 months of age, girls in the SGA group showed a marked increase in BMI‐for‐age. Among boys, the SGA group reached higher BMI‐for‐age values at preschool age than the DM and control groups. Differences were observed across time, group, and sex in the SGA and control groups ( p < 0.001). Conclusion These findings suggest that adverse intrauterine environments may influence BMI‐for‐age trajectories during early life, with greater variability and evidence of catch‐up growth among children exposed to maternal DM and SGA. Results should be interpreted cautiously due to unequal subgroup sizes and substantial loss to follow‐up at preschool age.
ABSTRACT Objectives Understanding patterns of growth elucidates the mechanism by which adult morphology arises, potentially informing us about the evolutionary history of these traits. We utilize the true longitudinal data from the Iowa Facial Growth Study (IFGS) to examine patterns of facial growth and development in relation to body mass index (BMI) and sex. Materials and Methods Our sample ( n = 77; 36 female) includes lateral cephalogram data at ages 4, 6, 8, 10, 12, and 14. Coordinate landmarks capturing facial shape were used to study facial size, facial shape, and facial form across growth. Cervical vertebral maturation was used as a secondary metric for skeletal maturation. We employed traditional and longitudinal statistics, such as mixed effects models, to examine trends in the data by BMI and sex. Results High BMI children have larger facial centroid sizes at Age 4 and maintain this trend through growth. Interestingly, unlike what is seen in dental development, this advanced skeletal development is not coupled with an apparent acceleration in the rate of skeletal development. We further can detect sex differences in facial size as young as the starting Age 4 timepoint ( p = 0.0014). Longitudinal analysis revealed differences in facial form early in ontogeny (Age 4), with all BMI groups nearing convergence at the final timepoint (Age 14). Discussion Our work demonstrates that variation in facial growth patterns related to BMI and sex is established early and maintained across growth. The growth of the craniofacial skeleton is likely influenced by a complex combination of genetic and environmental factors.
