Dose-response relationship between maternal thyroid hormones in the first twenty weeks and physical and neuropsychological development of infants: A prospective cohort study in China / 中华流行病学杂志

Objective: To study the dose-response relationship between maternal thyroid hormone levels in the first twenty weeks of pregnancy and the infant physical and neuropsychological development. Methods: In this prospective cohort study, a total of 945 women and their children were included. Maternal serum samples during first half of the pregnancy were collected and analyzed for levels of thyroid hormones by using the electro-chemiluminescence immunoassay. Maternal social demographic information was collected by using the a self-administered questionnaire. Physical measurements of newborns and neuropsychological evaluation of infants were performed by doctors of maternal and child health care. Results: The differences in newborns' birth length and head circumference were significant among the newborns of mothers with different percentiles of maternal serum (thyroid-stimulating hormone, TSH) levels (P<0.05). Newborns with maternal TSH level ≥P(95) or <P(5) had significantly lower birth length and birth head circumference, compared with the newborns with maternal TSH level between P(25)-P(75) (P<0.05). Newborns' birth head circumferences showed an inverted U-shaped association with maternal serum TSH level (Y=33.940+0.003X-0.109X(2), F=4.685, P=0.009). The difference in mental development index (MDI) of the infants at 18-30 months were significant among the infants of mothers with different percentiles of maternal serum TSH level (P<0.05). Infants with maternal TSH level ≥P(90) showed lower MDI (6.39, 95%CI: 2.29-10.49, P=0.002) compared with the infants with maternal TSH level between P(25)-P(75). Infant's MDI at 18- 30 months also showed an inverted U-shaped association with maternal serum TSH level (Y=103.249-1.524X-0.939X(2), F=6.616, P=0.001). Conclusions: Maternal TSH level was associated with newborn's birth length, birth head circumference and infant's MDI at 18-30 months. Newborn's birth head circumference and infant's MDI at 18-30 months showed an inverted U-shaped association with maternal serum TSH-Z score.

Exposure to bisphenol A during maternal pregnancy and the emotional and behavioral impact on their preschool children / 中华流行病学杂志

Objective: To explore the long-term effects of maternal pregnancy bisphenol A (BPA) exposure on emotional and behavioral problems appeared in their preschool children. Methods: The study sample was a subset of the China-Anhui Birth Cohort Study (C-ABCS). A unified questionnaire was used to collect basic information on both pregnant women and their children. Free BPA concentration in maternal serum was determined by high-performance liquid chromatographytandem mass spectrometry (HPLC-MS/MS). The parent-report version of the Strengths and Difficulties Questionnaire (SDQ) was used to estimate the emotional and behavioral problems in preschool children. A total of 1 713 pairs of mothers and children were included in this study. Association between BPA exposure during pregnancy and the emotional and behavioral problems in preschool children was evaluated with multinomial logistic regression model. Results: Prevalence rates in 1 713 preschool children appeared as: 6.48% of emotional problems, 8.11% for conduct problems, 8.35% for hyperactivity/inattention, 2.86% for peer problems, 11.38% for prosocial behaviors and 7.94% for total difficulties. Subjects were divided according to the degrees of exposure and the results showed as: low exposure group (≤0.120 ng/ml), medium exposure group (0.120<BPA<0.400 ng/ml) and high exposure group (≥0.400 ng/ml) according to the serum BPA concentration in tertile. Results from the multivariate logistic regression analysis showed that high level of maternal BPA exposure appeared a risk factor on children's abnormal conducts (OR=1.876, 95% CI: 1.161-3.029), more obvious in boys (OR=2.291, 95%CI: 1.126-4.661). Conclusion: Maternal exposure to high level of BPA during pregnancy might increase the detrimental effects of abnormal conducts in their preschool children, more obviously seen in boys.

Developmental characteristics of circadian rhythms in hypothalamic-pituitary-adrenal axis during puberty / 中华流行病学杂志

Objective: To explore the developmental characteristics of circadian rhythms in hypothalamus-pituitary-adrenal (HPA) axis during puberty. Methods: A total of 1 070 students from Grade 2-3 in 3 primary schools in Ma'anshan city, Anhui province, were selected for physical examination and circadian rhythm of HPA axis checked from 2015 to 2017. Saliva samples were collected at each of the following three time points: immediately upon wakening, 30 minutes after wakening and bedtime, with the index of circadian rhythm of HPA axis calculated, which including cortisol awake response (CAR), cortisol in puberty priming and diurnal cortisol slope (DCS). Testicular volume, palpation and visual inspection of breast development were used to assess the state of purbety development on boys and girls. Information on gender, date of birth, time to fall asleep, wake-up time and weekly physical activity were gathered through questionnaire survey. Non-parametric test was used to compare the differences of baseline, follow-up period and different adolescent developmental processes of each index on circadian rhythm of HPA axis. Results: During the period of follow-up program and comparing with the continuous undeveloped group, CAR and the changes of CAR showed significantly increase, both in the puberty priming group and continuous development group, with statistically significant differences (CAR: Z=8.551, 4.680, respectively; P<0.01; the changes of CAR: Z=4.079, 2.700, respectively, P<0.01). There were no significant differences noticed in CAR and the changes of CAR between puberty priming group or continuous development group. The area under the curve (AUC) of cortisol in puberty priming group was slightly higher than that in the persistent undeveloped group (Z=2.591, P=0.010). Both the changes of daily cortisol slope (DCS) in puberty priming group and continuing developed group decreased significantly, when comparing with those in continuous undeveloped group (Z=-2.450, Z=-2.151; all P<0.05). There was no significant difference noticed in the changes of cortisol in puberty priming and DCS between different puberty development stages (the changes of AUC: χ(2)=2.747, P=0.253; DCS: χ(2)=4.554, P=0.032). Conclusions: The indexes of circadian rhythm of HPA axis were associated with the development of puberty. Both the cortisol awakening response and the total amount of diurnal cortisol secretion showed an increase, along with the puberty development. The change of diurnal cortisol slope declined with the development of puberty.