Influence of gestational diabetes on circadian rhythms of children and their association with fetal adiposity.

OBJECTIVE: To analyse the circadian rhythm maturation of temperature, activity and sleep during the first year of life in offspring of diabetic mothers (ODM) and its relationship with obesity markers. METHODS: A prospective analysis of the children of 63 pregnant women (23 controls, 21 gestational diabetes mellitus (GDM) controlled with diet and 19 GDM with insulin). Fetal abdominal circumference was evaluated ecographically during gestation. Skin temperature and rest-activity rhythms were monitored for 3 consecutive days in children at 15 days and 1, 3 and 6 months. Anthropometrical parameters of the children were evaluated during the first year of life. RESULTS: Children from the GDM groups tended to higher fetal abdominal circumference z-score than controls at the beginning of the last trimester (p = 0.077) and at delivery (p = 0.078). Mean skin temperature or activity was not different among the groups. The I < O sleep index pointed to increasing concordance with parental sleeping at 3 and 6 months but no significant GDM-dependent differences. However, some of the parameters that define temperature maturation and also the circadian function index from the temperature-activity variable were significantly lower at 6 months in the GDM + insulin group. Fetal abdominal circumference z-score, as a predictor of fetal adiposity, correlated negatively with parameters related to circadian rhythm maturation as the circadian/ultradian rhythm (P1 /Pult ratio). CONCLUSIONS: Fetal adiposity correlated with a worse circadian rhythm regulation in ODM. In addition, ODM insulin-treated showed a disturbed pattern of the circadian function index of temperature activity at 6 months of age.

Assessment of circadian rhythms of both skin temperature and motor activity in infants during the first 6 months of life.

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 P(1)/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.