The authors developed a method useful for home measurement of temperature, activity, and sleep rhythms in infants under normal-living conditions during their first 6 mos of life. In addition, parametric and nonparametric tests for assessing circadian system maturation in these infants were compared. Anthropometric parameters plus ankle skin temperature and activity were evaluated in 10 infants by means of two data loggers, Termochron iButton (DS1291H, Maxim Integrated Products, Sunnyvale, CA) for temperature and HOBO Pendant G (Hobo Pendant G Acceleration, UA-004-64, Onset Computer Corporation, Bourne, MA) for motor activity, located in special baby socks specifically designed for the study. Skin temperature and motor activity were recorded over 3 consecutive days at 15 days, 1, 3, and 6 mos of age. Circadian rhythms of skin temperature and motor activity appeared at 3 mos in most babies. Mean skin temperature decreased significantly by 3 mos of life relative to previous measurements (p = .0001), whereas mean activity continued to increase during the first 6 mos. For most of the parameters analyzed, statistically significant changes occurred at 3–6 mos relative to 0.5–1 mo of age. Major differences were found using nonparametric tests. Intradaily variability in motor activity decreased significantly at 6 mos of age relative to previous measurements, and followed a similar trend for temperature; interdaily stability increased significantly at 6 mos of age relative to previous measurements for both variables; relative amplitude increased significantly at 6 mos for temperature and at 3 mos for activity, both with respect to previous measurements. A high degree of correlation was found between chronobiological parametric and nonparametric tests for mean and mesor and also for relative amplitude versus the cosinor-derived amplitude. However, the correlation between parametric and nonparametric equivalent indices (acrophase and midpoint of M5, interdaily stability and Rayleigh test, or intradaily variability and P₁/P_ultradian) despite being significant, was lower for both temperature and activity. The circadian function index (CFI index), based on the integrated variable temperature-activity, increased gradually with age and was statistically significant at 6 mos of age. At 6 mos, 90% of the infants' rest period coincided with the standard sleep period of their parents, defined from 23:00 to 07:00 h (dichotomic index I < O; when I < O = 100%, there is a complete coincidence between infant nocturnal rest period and the standard rest period), whereas at 15 days of life the coincidence was only 75%. The combination of thermometry and actimetry using data loggers placed in infants' socks is a reliable method for assessing both variables and also sleep rhythms in infants under ambulatory conditions, with minimal disturbance. Using this methodological approach, circadian rhythms of skin temperature and motor activity appeared by 3 mos in most babies. Nonparametric tests provided more reliable information than cosinor analysis for circadian rhythm assessment in infants. (Author correspondence: elvirada@um. es )

Background: Obesity is a major public health crisis among both children and adults and contributes to significant physical, psychological, and economic burden. We aim to investigate the effect of duration of breastfeeding on excessive weight and obesity at 6 years of age. Subjects/Methods: Data on breastfeeding and child anthropometric measurements were collected in a birth-cohort study in Murcia, Spain (n = 350). Breastfeeding status and body mass index (BMI) were established according to WHO definitions. Other factors potentially related to children's weight were considered. Multiple log-linear and ordinal regressions were used to analyze the effects of breastfeeding on overweight and obesity when considering potential confounders. Results: 33% and 17.3% of children in the study were of excess weight and obesity, respectively. Univariate predictors of BMI in children aged 6 were as follows: pregestational maternal BMI (kg/m²) (R² = 0.127, p < 0.01); full breastfeeding (weeks) R² = −0.035, p < 0.01); infant weight gain (kg) (R² = 0.348, p < 0.01); and maternal alcohol consumption during pregnancy (g/day) (R² = 0.266, p < 0.01) at age 6. In the ordinal logistic regression, full breastfeeding was associated with a significant decrease in obesity −0.052 (95% CI, −0.10 to −0.003). Conclusions: The delay of bottle feeding introduction may have a protective effect against obesity at 6 years of age. Our findings reinforce the need for greater support of breastfeeding and to promote a healthy environment and antipoverty interventions during pregnancy and infancy, alongside other strategies for obesity prevention.

Background: The relationship between parent-reported and measured height and weight is not well established in schoolchildren. This relationship has never been studied in asthmatic children. The objective of this study is to test the validity of the parent-reported weight and height for defining obesity by BMI and to know whether the perception of this height and weight changes when the child suffers from asthma. Methods: All classes of children of the target ages of 6–8 years (n = 1,672, participation rate 70.2%) of all schools in four municipalities of Murcia (Spain) were included. Parents were asked about their children’s weight and height using a questionnaire which included the International Study of Asthma and Allergies in Childhood (ISAAC) core questions on asthma. Parents were not aware that their children were going to be weighed and measured within 1 week’s time. Measurements were performed using a rigid stadiometer to the nearest 0.1 cm and a scale to the nearest 0.1 kg. Results: The bias (reported minus real) was, respectively, for nonasthmatics and asthmatics: weight +0.42 kg (95% CI +0.24; +0.59 kg) versus +0.97 kg (+0.50; +1.44 kg), height +2.37 cm (+2.06; +2.68 cm) versus +2.87 cm (+1.87; +3.87 cm); BMI –0.39 kg/m2 (–0.52; –0.23 kg/m2) versus –0.23 kg/m2 (–0.58; +0.13 kg/m2). Diagnostic accuracy of obesity calculated from reported measurements was, respectively, for nonasthmatics and asthmatics: sensitivity 78.0 versus 77.8%, specificity 96.2 versus 94.5%, positive predictive value 77.2 versus 73.7% and negative predictive value 96.4 versus 91.7%. Conclusions: Reported weights and heights had large biases, comparable between parents of both asthmatic and those of nonasthmatic children. However, this information could be reasonably valid for classifying children as obese or nonobese in large epidemiological studies.