Relationship between pre-pregnant body mass index, maternal weight gain and small for gestational age / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate the relationship between maternal pre-pregnancy body mass index, weight gain during pregnancy and small for gestational age (SGA) birth so as to provide evidence for the development of comprehensive prevention programs on SGA birth.</p><p><b>METHODS</b>Between March, 2012 and July, 2014, 4 754 pregnant women were asked to fill in the questionnaires which were collected from the First Affiliated Hospital of Shanxi Medical University. Data related to general demographic characteristics, pregnancy and health status of those pregnant women was collected and maternal pre-pregnancy body mass index and maternal weight gain were calculated. Subjects were divided into different groups before the effect of maternal pre-pregnancy body mass index and weight gain during pregnancy on SGA birth were estimated.</p><p><b>RESULTS</b>The overall incidence of SGA birth was 9.26% (440/4 754). Proportions of SGA birth from pre-pregnant, underweight group, normal weight group, overweight and obese groups were 9.85%, 8.54% and 9.45%, respectively. Results from multi-factor logistic regression analyses showed that after adjusting the confounding factors as age, history on pregnancies etc., women with high pre-pregnancy BMI showed a lower incidence of SGA than those under normal pre-pregnancy BMI (OR = 0.714, 95% CI: 0.535-0.953). Different weight gains during pregnancy were statistically significant (χ(2) = 8.811, P = 0.012). Incidence of SGA birth that was below the recommended range in the 2009 Institute of Medicine Guidelines (12.20%) was higher than those within (9.23%) or beyond (8.45%) the recommended range. Results from the multi-factor logistic regression analyses showed that, after adjusting the confounding factors as age, pregnancy history etc., factor as weight gain below the recommended level could increase the risk of SGA (OR = 1.999, 95% CI: 1.487-2.685). In the underweight, normal weight, overweight or obese groups, with weight gain during pregnancy below the range, the incidence of SGA showed an increase (OR = 2.558, 95% CI: 1.313-4.981, OR = 1.804, 95% CI: 1.258-2.587, OR = 3.108, 95% CI: 1.237-7.811). There was no interaction of addictive or multiplicative models between these two factors under 'interaction analysis'.</p><p><b>CONCLUSION</b>Women with high pre-pregnancy BMI presented a lower incidence of SGA than those within the normal range. Insufficient weight gain during pregnancy could increase the risk of SGA delivery. These findings called for attention to be paid to the gestational weight gain, in order to decrease the risk of SGA.</p>

Study on risk factors of hepatitis B virus infection among patients receiving hemodialysis by multi-level statistical model analysis / 中华流行病学杂志

<p><b>OBJECTIVE</b>To understand the current status of HBV infection among patients receiving maintenance hemodialysis (MHD) and related influencing factors.</p><p><b>METHODS</b>A questionnaire survey was conducted among 1,524 MHD patients selected from hemodialysis units in 16 hospitals in Shanxi province from 1 November 2012 to 30 December 2014 to collect their demographic information and learn about their risk behaviors. Serological detection was conducted for them. Statistical software package SAS 9.3 was used for fitting a two level logistic regression model to identify the independent risk factors for HBV infection.</p><p><b>RESULTS</b>Among the 1 524 MHD patients, the positive rate of HBsAg was 5.25% and the HBV infection rate was 38.85%. The HBV infection rate varied with hospital (t=2.33, P=0.034). The two-level logistic regression empty model showed that intra-class correlation coefficient was 0.106 4, indicating that about 10.64% of the total variation was caused by the differences in hospitals. After introducing explaining variables, the results showed that the HBV infection rate in age group 50-65 years group was higher than that in age group 0-35 years (OR=1.560, 95% CI: 1.061-2.293). Family history of HBV infection and dental surgery were the risk factors for HBV infection (OR=2.052 and 1.267, 95% CI: 1.176-3.582 and 1.009-1.591). Receiving HepB vaccination was a protective factor for HBV infection (OR=0.734, 95% CI: 0.541-0.996).</p><p><b>CONCLUSION</b>The HBV infection rates were different among MHD patients in different hospitals. Old age (50-65 years), family history of HBV infection and dental surgery were the risk factors and receiving HepB vaccination was a protective factor for HBV infection among MHD patients.</p>