Objective To investigate the effect of illness severity on preterm infant's hypothalamusputituary-adrenal (HPA) axis, we measured the serum concentration of cortisol,aldosterone and adrenocorticotropic hormone (ACTH). Methods Ninety preterm infants who were transferred to our hospital within 72 hours after birth were involved. These preterm infants were divided into two groups:gestational age (GA) ≥34 weeks' preterm infants and GA <34 weeks' preterm infants. We evaluated these preterm infants at the time of admission,day 7 and day 14 after birth with neonatal critical illness score (NCIS). Then they were divided into mild group and severe group by the lowest score. We measured their serum cortisol,aldosterone and ACTH at the time of admission,day 7 and day l4 after birth. Results (1) The serum cortisol concentration of preterm infants with severe illness was higher than that of preterm infants with mild illness. Among the GA ≥34 weeks' preterm infants,the serum cortisol concentration of preterm infants with severe illness was significandy higher than that of preterm infants with mild illness within 72 hours after birth (t = -2.263,P =0. 029). Among the GA <34 weeks' preterm infants,the serum cortisol concentration of preterm infants with severe illness was significantly higher than that of preterm infants with mild illness on day 14 after birth (t =-2. 913 ,P =0. 006). (2) Among the preterm infants with severe illness,the serum cortisol concentration of the GA≥34 weeks' was significantly higher than that of the GA < 34 weeks' within 72 hours after birth (t =-2. 641 ,P =0. 010) ;the serum cortisol concentration of the GA <34 weeks' was significantly higher than that of the GA≥34 weeks' on the day 14 after birth(t = -2. 189,P =0. 036) . (3) The serum cortisol concentration was significantly decreased in the GA≥34 weeks'preterm infants (F = 4. 679, P =0. 012). (4) The serum cortisol concentration of aldosterone and ACTH was not significantly different between preterm infants with severe illness and those with mild illness. Conclusion The preterm infant already has the ability to respond to stimuli by regulating cortisol secretion. The serum cortisol concentration increases as disease severity worsens.Serum aldosterone and ACTH concentration are not correlated with the severity of the disease.

Objective: To investigate the effect of elective cesarean section (ECS) on infants' developmental behaviors. Methods: A total of 3 474 pregnant women living in Ma'anshan more than 6 months and accepting obstetric examination in Ma'anshan Maternal and Child Care Center were recruited from May 2013 to September 2014. Excluding participants with pregnancy termination (162), twin pregnancy (39), assisted delivery (14), emergency cesarean section (76) and unclear delivery mode (141), 3 042 pair of mother and infant entered the final analysis. Information of maternal basic demographic characteristics, pregnancy histories, pregnancy life style and pregnancy-related diseases were collected by using self-complied Maternal and Child Health Questionnaire. Information of infants' general condition and delivery modes were acquired from obstetric record. The Ages and Stages Questionnaires-third edition was used to assess infants' communication, gross motor, fine motor, problem solving and person-social function, which was completed at age of 6 months old and 18 months old, respectively. And multi-factor non-conditional logistic regression model was used to analyze the association between ECS and infants' developmental behaviors. Results: The prevalence of ECS was 47.5% (1 443/3 042), among which ECS without medical indication and ECS with medical indication were 27.2% (826/3 042) and 20.3% (617/3 042), respectively. After maternal demographic characteristics, pregnant exposure and infants' basic information adjusted, compared to women with vaginal delivery, both ECS with medical indication and without medical indication increased the risk of a delay in gross motor on infants at 6 months old (RR (95%CI: 1.72 (1.08-2.77) and 1.87 (1.11-3.15), respectively.) ECS without indication decreased the risk of a delay in fine motor on infants at 6 months old (RR (95%CI):0.48 (0.28-0.82)), both ECS without medical indication and with medical indication had no statistically significant effect on 18 months infants' communication, gross motor, fine motor, problem solving and person-social function, the RR (95%CI) for ECS without medical indication were 0.86 (0.43-1.74), 1.55 (0.86-2.78), 0.74 (0.49-1.15), 1.10 (0.68-1.78) and 1.17 (0.66-2.08), respectively; and the RR (95%CI) for ECS with medical indication were 0.33 (0.12-1.02), 1.10 (0.55-2.21), 0.79 (0.48-1.29), 0.58 (0.29-1.13) and 1.48 (0.78-2.81), respectively. Conclusion ECS affected motor development in infants at the age of 6 months old, and no influence was found in infants at the age of 18 months old.

Objective: To study serum zinc level in pregnancy and umbilical cord blood and their association with newborn birth weight. Methods: Pregnant women accepting obstetric examination in Ma'anshan Maternal and Child Care Center were recruited from May 2013 to September 2014. The follow up was conducted during their first, second and third trimesters of pregnancy and the self-designed questionnaire was used to collect information of social and demographic characteristics. Blood samples in the first, second pregnancy period and umbilical cord blood samples were collected and serum concentrations of zinc were assayed. 3 239 mother-infant entered the final analysis. We divided serum zinc level into low (<P₂₅), medium (P₂₅-P₇₅) and high (>P₇₅) groups according to their exposure concentrations at each trimesters. Non-conditional multivariate logistic regression model was conducted to evaluate the association between serum zinc level in first, second trimesters of pregnancy and umbilical cord blood with small for gestational age (SGA) and large for gestational age (LGA). Results: Serum zinc level in P₅₀ (P₂₅-P₇₅) during the first, second trimesters and cord blood were 1 016.18 (907.09-1 145.60), 813.36 (732.47-897.89) and 903.44 (808.71-1 015.64) μg/L, respectively. The prevalence of zinc deficiency during the first, second trimesters and cord blood were 1.5% (44/2 957), 15.9% (492/3 087) and 6.5% (176/2 707), respectively. The prevalence of total SGA and LGA were 9.7% (313/3 239) and 16.5% (536/3 239), respectively. Compared to high-level serum zinc group, the risk of SGA (OR (95%CI) in low-level serum zinc group during first trimesters was 1.51 (1.05-2.19)). Serum zinc level among second pregnancy period and umbilical cord blood had no statistically significant effect on SGA and LGA (both P values >0.05). Conclusion Zinc nutritional status of pregnant women in Ma'anshan city was at a good level. The low serum zinc level in first trimester increased the risk of SGA.