Establishment and evaluation of enzyme-linked immunosorbent assay for measuring human IgM autoantibody to folate receptor / 中国医学科学院学报

<p><b>OBJECTIVE</b>To establish the method of enzyme-linked immunosorbent assay (ELISA) for measuring human IgM autoantibody to folate receptor.</p><p><b>METHODS</b>Folate receptor was extracted and purified from the healthy woman placenta. The protein was coated on 96-well plates with a concentration of 5 ng/Μl. Goat monoclonal antibody was used for detecting antibody. Pooled plasma from healthy donors was used to plot the standard curve and the IgM concentration of pooled plasma was defined as 1. We set up an ELISA procedure to measure human IgM autoantibody to folate receptor. The sensitivity, precision, and stability of the method were evaluated. Further, the folate receptor and bovine folate-binding protein were used as the antigen, respectively, to determine the autoantibody levels in 24 healthy individuals and 20 individuals once gave birth to baby with neural tube defects.</p><p><b>RESULTS</b>The measuring range of the method was from 6.25 × 10⁻⁴ to 8.00 × 10⁻². The lowest IgM level that can be detected was 3.12 × 10⁻⁴. The inter-assay coefficients of variations for samples with high, medium, and low IgM levels were 6.61%,3.50%, and 5.12%, respectively. The intra-assay coefficients of variations were 4.54%, 5.49%, and 5.44%, respectively. The stability test results were considered within acceptable limits. The data from folate receptor-ELISA was significantly higher than that from bovine folate binding protein-ELISA, both in the healthy group (t=-11.9, P<0.001) and in the neural tube defect group (t = 7.35, P<0.001).</p><p><b>CONCLUSIONS</b>The folate receptor-ELISA method for measuring human IgM autoantibody to folate receptor was successfully established. The method is sensitive, repeatable, and stable.</p>

Impact of pregnancy terminations before 28 weeks of gestation on the overall prevalence of neural tube defects in two counties of Shanxi province / 中华流行病学杂志

Objective To examine the impact of pregnancy termination before 28 weeks of gestation on the overall prevalence of neural tube defects (NTDs).Methods Data collected during the period of 2004 and 2010 from a birth defects surveillance system in Pingding county and Talgu county of Shanxi province were used.Number of births ≥28 weeks of gestation and number of cases with major birth defects among the births were collected.Terminations of pregnancies before 28 weeks of gestation due to prenatal diagnosis were also collected.The total prevalence of neural tube defects,prevalence before 28 weeks of gestation,and prevalenee of ≥28 weeks gestation were calculated using the total number of pregnancies of ≥28 weeks of gestation as denominator.The prevalence data were compared to examine the impact of pregnancy termination on the total prevalence.The proportions of pregnancy terminations before 28 weeks of gestation due to prenatal diagnosis of an NTD against the total number of NTD cases were also calculated.Results During 2004-2010,52 366 births were recorded,and 485 NTD cases were ascertained.The overall prevalence of NTDs was 92.6 per 10 000 births,with prevalence of ＜28 weeks gestation due to pregnancy terminations as 60.9 per 10 000 births,while the prevalence of ≥28 weeks of gestation was 31.7 per 10 000 births.NTD prevalence of ≥28 weeks gestation was 66.0％ lower than the total NTD prevalence.In the last two years,the proportion of NTDs ascertained ≥28 weeks gestation accounted for about 40.0％ of the total NTD cases.Conclusion A birth-defect-surveillance program that covered only tregnancies ≥28 weeks of gestation resulted in a severe underestimation of the total birth prevalence of NTDs,especially for anencephaly.We would recommend that the current national birth defects surveillance system should include pregnancy terminations before 28 weeks of gestation and the calculation of total NTD prevalence should also include these cases into the numerator,so as to better estimate true population NTD prevalence,upon which the related public health policy is based.

Maternal periconceptional consumption of pickled vegetables and risk of neural tube defects in offspring / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Maternal exposure to nitrate, nitrite, and N-nitroso compounds from drinking water or diet has been associated with an increased risk of neural tube defects (NTDs) in some studies. Pickled vegetables contain relatively large amounts of nitrite and N-nitroso compounds. We examined the association between maternal periconceptional consumption of pickled vegetables and NTDs in Shanxi Province of northern China.</p><p><b>METHODS</b>Data were derived from a population based case-control study of major external birth defects in four counties of Shanxi Province. Participants included 519 NTDs cases identified between 2003 and 2007 and 694 healthy controls. Exposure information was collected within 1 week after delivery. Multivariable non-conditional Logistic regression model was used to estimate the adjusted odds ratio (OR) controlling for potential confounding variables.</p><p><b>RESULTS</b>The risk of NTDs was positively associated with the frequency of the consumption of pickled vegetables by the mother. Compared with pickled vegetables consumption at < 1 meal/week, the adjusted OR for consumption at 1 - 3, 4 - 6, and > 6 meals/week were 1.3 (95% confidence interval (CI): 1.0, 1.8), 1.9 (1.1, 3.2), and 3.6 (1.9, 6.9), respectively. A protective effect was found for maternal meat consumption at ≥ 1 meal/week (adjusted OR: 0.6, 95%CI: 0.4, 0.7) and egg or milk consumption at ≥ 1 meal/week (adjusted OR: 0.6, 95%CI: 0.4, 0.8).</p><p><b>CONCLUSION</b>Maternal periconceptional consumption of pickled vegetables may increase the risk for NTDs in Shanxi Province.</p>

Cesarean delivery on maternal request and childhood intelligence: a cohort study / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Cesarean section births have been steadily increasing over the past decade and have become an epidemic in China. Cesarean delivery on maternal request is a major contributor to this upward trend, and there has been of much concern about its impact on maternal and child health. Most of mothers believe that cesarean delivery on maternal request can improve the child's intelligence, but direct evidence is sparse. In this cohort study, we aimed to directly assess the impact of cesarean delivery on maternal request on childhood intelligence.</p><p><b>METHODS</b>Intelligence quotient (IQ) of 4144 preschool children from 21 cities/counties of Zhejiang and Jiangsu province whose mothers were registered in a population-based perinatal surveillance program during 1993-1996 was assessed with Chinese Wechsler Young Children Scale of Intelligence (C-WYCSI) in 2000. The outcomes were full-scale IQ, verbal IQ, and performance IQ of C-WYCSI. Mode of delivery and covariates were obtained from the surveillance program. We estimated unadjusted and adjusted effects of cesarean delivery on maternal request and assisted vaginal delivery on IQ scores compared with spontaneous vaginal delivery using regression analysis.</p><p><b>RESULTS</b>The mean full-scale, verbal, and performance IQ for all children was 99.3 ± 16.1, 93.6 ± 17.7, and 105.3 ± 14.3. In crude analysis, cesarean delivery on maternal request versus spontaneous vaginal delivery was associated with an increase of 3.9 (95% confidence interval, 0.6 to 7.2) points in full-scale IQ, 4.8 (1.2 to 8.4) points in verbal IQ, and 2.4 (-0.6 to 5.3) points in performance IQ. After adjusting for maternal education, occupation, and IQ, the advantage was reduced to 1.6 (-1.3 to 4.5), 2.3 (-0.8 to 5.5), and 0.6 (-2.0 to 3.3) points for full-scale, verbal, and performance IQ, respectively. Assisted vaginal delivery versus spontaneous vaginal delivery was not associated with IQ scores in any analysis.</p><p><b>CONCLUSION</b>Neither cesarean delivery on maternal request nor assisted vaginal delivery affected children's IQ.</p>

Questionnaire-based survey of allergic diseases among children aged 0 - 14 years in the downtown of Beijing, Chongqing and Guangzhou / 中华儿科杂志

<p><b>OBJECTIVE</b>In recent years, the incidence of allergic diseases in China is increasing. With serious influence on the patients' quality of life and even life-threatening, now allergic diseases have become an important public health problem in our country. This survey aimed to obtain a general epidemic outline of children's major allergic diseases, i.e., childhood asthma, allergic rhinitis and eczema in the downtown of Beijing, Chongqing and Guangzhou.</p><p><b>METHOD</b>Childhood asthma questionnaire was established by Delphi method based on guidelines for childhood asthma diagnosis and prevention made by Chinese medical association in 2008 with reference to the International Study of Asthma and Allergies in Childhood questionnaire (ISAAC). This study was carried out from Oct. 2008-Mar. 2009, in Beijing, Chongqing and Guangzhou by a multi-stage sampling method, covering a sample of 24 290 children aged 0 - 14 years by a multi-stage sampling method, the population of children surveyed in the downtown of Beijing Chongqing and Guangzhou was 10 372, 9874 and 4072 respectively; of whom males were 5545, 5258, 2159, and females were 4917, 4588, 1877; the ratio of males to females in the three cities were 1.11:1, 1.15:1, 1.15:1; the average age of surveyed children were 7.63, 8.74 and 8.30 years old. All the questionnaire was filled in by the parents of children or other guardian of children.</p><p><b>RESULT</b>The self-reported prevalence of asthma in Beijing, Chongqing and Guangzhou was 3.15%, 7.45%, 2.09%, the self-reported prevalence of allergic rhinitis was 14.46%, 20.42%, 7.83%, and the prevalence of eczema was 20.64%, 10.02%, 7.22%. In the survey, asthma combined with allergic rhinitis had the highest rate, 49.54%, 50.14%, 34.83%, respectively in the 3 cities. The self-reported prevalence of asthma and allergic rhinitis was significantly higher in male than female. Besides, the self-reported prevalences of asthma and allergic rhinitis were relatively lower in children under 1 year and over 10 years of age.</p><p><b>CONCLUSION</b>The prevalence of asthma, allergic rhinitis and eczema and other allergic diseases in children 0 - 14 years of age in the three cities gradually increased, and the prevalence of allergic diseases in Chongqing was relatively higher.</p>

Correlation on hemoglobin concentration and the development of cognition among pre-school children / 中华流行病学杂志

Objective Our purpose was to evaluate the association between hemoglobin concentration (Hb) and cognitive ability of children at 4-6 years of age in 21 counties/cities in China.Methods A total number of 7331 children born during 1993-1996 were randomly selected from 21 counties or cities in Hebei,Jiangsu and Zbejiang provinces,Hb concentration of children were measured followed by three tests including full-scale,verbal and performance intelligence quotient (IQ) test performed by Chinese-Wechsler Intelligence Scale for Children,one year later.Results There were a 0.7 point difference in mean verbal scale IQ(P=0.144) and a 0.9 point difference in both mean performance and full-scale IQ (P=0.055 and 0.079,respectively) between anemia and non-anemia groups.Compared with children with non-anemia,children with anemia were 1.3-fold more likely to score poorly in verbal IQ and operational IQ (95%CI:1.1-1.6,1.1-1.5,respectively) and 1 A-fold more likely to have had poor scores in full-scale IQ(95%CI:1.2-1.6) after controlled for children's gender,age at intelligence test,region,parity and mother's IQ,education level,occupation.Participants were divided into 5 sub-groups according to Hb concentration of every 20 percentile.Verbal IQ scores of the lowest(Hb＜110 g/L),moderate (117 g/L≤Hb＜122 g/L) and the highest Hb concentration groups (Hb≥130 g/L) were 90.6±18.1,94.0±17.6 and 91.0±16.4,respectively.Performance IQ scores were 102.2±15.7,104.6±14.8 and 100.5±14.9,respectively.Full-scale IQ scores were 95.94±17.3,99.0±16.4 and 95.2±15.6,respectively.Children with both low and high hemoglobin levels did poorly in all intelligence tests than children with moderate Hb concentration (P＜0.001).After controlling for confounding factors,children with the lowest concentration were 1.4-fold more likely to have had poor verbal and performance scores than children with moderate Hb concentration (95% CI:1.1-1.7,1.1-1.8,respectively) and 1.5-fold (95% CI:1.2-1.8) more likely to have had poor full-scale scores than those with moderate Hb concentration.The association between high Hb concentration and low IQ scores disappeared in the multivariate model.Conclusion Low Hb concentration might have adversely affected children' s cognitive development.

Prospective cohort study of pregnancy-induced hypertension and risk of preterm delivery and low birth weight / 中华预防医学杂志

<p><b>OBJECTIVE</b>To determine the association between pregnancy-induced hypertension(PIH) and risk of preterm delivery (PD) and low birth weight (LBW).</p><p><b>METHODS</b>A prospective cohort was established based on 131 867 women who delivered a singleton baby in seven cities or counties in Zhejiang province, China, during the period of 1995 - 2000. The exposure group included 14 278 women who were diagnosed as PIH, and the non-exposure group included 117 589 women. The exposure group was divided into mild, moderate, and severe subgroups based on the severity of PIH, and further divided into early, medium and late onset subgroups based on the time of onset of PIH (occurred in second trimester, third trimester, or during delivery). The primary outcome measures were the incidence of PD and LBW. Multiple logistic regression was used to estimate relative risk and 95% confidence intervals after adjustment by maternal age, occupation, education, parity, number of prenatal visits, gestational disease, caesarean delivery, pregnant body mass index, fetal sex, and gestational age (only for LBW).</p><p><b>RESULTS</b>The incidence rates of PD and LBW in exposure group were 4.9% (701/14 278) and 3.6% (507/14 278), and both rates were higher than those of the non-exposure group (3.4% (4031/117 589), 1.8% (2110/117 589)) (chi(2) values were 80.8 and 202.0, P < 0.001). The incidence rates of PD in mild, moderate, and severe subgroups were 3.9% (404/10 358), 5.8% (181/3099), and 14.1% (116/821), and corresponding incidence rates of LBW were 2.5% (258/10 358), 4.9% (151/3099), and 11.9% (98/821). Both rates were increased with the severity of PIH (chi(2) values were 196.4 and 426.1, P-value for trend < 0.001). The incidence rates of PD in early, medium, and late onset subgroup were 8.4% (50/598), 5.7% (278/4867), and 4.2% (373/8813), and corresponding incidence rates of LBW were 5.7% (34/598), 4.2% (206/4867), and 3.0% (267/8813). Both rates were decreased by the time of PIH onset (chi(2) values were 115.4 and 239.8, P-value for trend < 0.001).</p><p><b>CONCLUSION</b>PIH could increase the incidence of PD and LBW.</p>

Analysis on influencing factors for stunting and underweight among children aged 3-6 years in 15 counties of Jiangsu and Zhejiang provinces / 中华流行病学杂志

Objective To analyze the influencing factors for stunting and underweight among children aged 3-6 years in 15 counties of Jiangsu and Zhejiang provinces so as to provide reference for enhancing growth level among preschool children. Methods Data was from the 183 295 records of Children Follow-up Study Project carried out by the Institute of Reproductive and Child Heath of Peking University and the records of related perinatal health care surveillance system in rural areas of 15 counties/cities of Jiangsu and Zhejiang provinces. WHO-NCHS standard was used to assess the childhood physical level of growth. Data of children's birth and their mothers' perinatal health were correlated to determine influencing factors for childhood stunting and underweight. Results The average stunting rate was 7.95% and underweight rate was 1.55%. Sex, birth weight, preterm birth as well as maternal height, maternal BMI at the first prenatal visit, maternal education and occupation were significantly related to childhood stunting and underweight. Birth weight was the most important influencing factor for childhood underweight. For the groups whose birth weights were ＜2500 g and ≥2500 g, the rates of underweight were 7.77% and 1.46% respectively. Children with low birth weight were at higher risk for underweight (OR=3.68,95% CI: 3.11-4.37). Maternal height was the most important influencing factor for childhood stunting. For the groups whose mothers' heights were ＜155 cm, 155-160 cm, 160-165 cm and ≥165 cm, the stunting rates were 13.01%, 8.76%,6.21% and 4.14% respectively. Compared with the ≥165 cm group, the ＜155 cm group was at higher risk for stunting (OR=3.08, 95% CI: 2.82-3.37). Conclusion Birth weight and maternal height were key factors influencing the growth of children. Perinatal health care and the nutrition starus of pregnant mothers should be improved to promote the growth level of preschool children.

Current trends of the prevalence of childhood asthma in three Chinese cities: a multicenter epidemiological survey / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To analyze the prevalence of asthma and asthma related symptoms among children aged 0-14 years in three Chinese cities and to obtain a crude estimation of the trend of childhood asthma prevalence in China.</p><p><b>METHODS</b>A cross-sectional, population-based survey of prevalence of asthma was conducted in children aged from 0 to 14 years in 3 major cities of China (Beijing, Chongqing, and Guangzhou) with different geographic locations. All the subjects were randomly selected by a multi-stage sampling method. Three to five schools and kindergartens in 2 urban districts in each city were randomly selected for the survey, and a validated questionnaire that included the core questions of the International Study of Asthma and Allergies in Childhood, Phase III questionnaire and several additional questions were used. All questionnaires were completed by parents or guardians of the selected children. Children whose parents responded affirmatively to the question "Has your child ever been diagnosed as asthma by a doctor" were recognized as victims of asthma.</p><p><b>RESULTS</b>The prevalence of asthma in Beijing, Chongqing, and Guangzhou was 3.15%, 7.45%, and 2.09%, respectively. These values were significantly higher than those obtained 10 years ago in the national epidemiological survey in 2000 which used the same method of investigation and the same diagnotic criteria (χ²=3.938, P=0.047; χ²=73.506, P≤0.001; χ²=11.956, P=0.001, in each city). Of the asthmatic children 57.21%, 69.91%, and 60.00% had their first attack before the age of 3 in Beijing, Chongqing, and Guangzhou, respectively. Wheezing was the primary clinical manifestation for all asthmatic children, followed by persistent cough and repeated respiratory infections. Both the prevalence of asthma and asthma-related symptoms were statistically higher in males than in females.</p><p><b>CONCLUSION</b>The prevalence of childhood asthma is statistically higher than that 10 years ago in the three Chinese cities.</p>

Study on the current status of spontaneous abortion of primigravid women in Jiaxing of Zhejiang province, China / 中华流行病学杂志

Objective To study the current status of spontaneous abortion of primigravid women in Jiaxing areas of Zhejiang province of China. Methods We analyzed the data from both perinatal healthcare surveillance program and spontaneous abortion, collected in Jiaxing areas by the Institute of Reproductive and Child Health, Peking University. The study population consisted of 14 769 primigravid women (excluding induced abortion, ectopic pregnancy and molar pregnancy as outcomes) attempting to become pregnant who registered between 1993 and 1995. Results 1454 spontaneous abortion cases were identified, with the spontaneous abortion rate as 9.8% (95% CI:9.3%-10.3%). The mean gestational weeks at pregnancy diagnosis were 7.6±2.1 weeks, the mean gestational weeks at miscarriage were (10.1±3.1) weeks and the incidence of first-trimester (≤12 weeks) spontaneous abortion was 7.3%(95%CI: 6.8%-7.7%), accounting for 73.7% of all the spontaneous abortion cases. A peak for risk of miscarriage was around 8-13 weeks, accounting for 37.7% of all spontaneous abortion. The observed multiple Cox regression model showed that increased spontaneous abortion rates were observed in women with age at pregnancy ≥30, being peasants and with higher education level. Conclusion The spontaneous abortion rate of primigravid women in Jiaxing areas was higher than in other areas of China. The maximum occurrence of spontaneous abortions was during period of 8-13 gestation weeks.

Influence of hemoglobin level during early gestation on the development of cognition of preschool children / 中华流行病学杂志

Objective The purpose of this study was to evaluate the effect of hemoglobin (Hb) level during early gestation on the cognitive development of children at 4-6 years of age.Methods A total number of 3609 children were randomly selected from all the live birth infants whose mothers participated in a community intervention trial during 1993-1996 in 13 counties or cities in Jiangsu and Zhejiang provinces. Hb concentration during early gestation was measured at first prenatal examination and intelligence quotients (IQ), including full-scale, verbal and performance were assessed using Chinese-Wechsler Intelligence Scale for Children in 2000-2001 when these children had a mean age of 68 months. Results Compared with children whose mothers were non-anemic during early gestation, children whose mothers were anemic had a 0.6 point higher mean verbal scale IQ, a 0.9 point higher mean performance IQ and a 0.8 point higher mean full-scale IQ.These differences were not statistically significant when children' s gender, age at intelligence test,region, parity and mother' s IQ, education level and occupation were adjusted for. When mother-child pairs were divided into 5 sub-groups of every 20 percentiles according to Hb concentration during early gestation, verbal IQ scores of the lowest(Hb＜ 103 g/L), the moderate(110 g/L≤ Hb＜ 116 g/L)and the highest Hb concentration group (Hb≥124 g/L) were 91.6 ± 18.9, 92.8 ± 18.2 and 90.3 ±18.6, respectively. The performance IQ scores were 104.7 ± 15.2, 1 04.5 ± 14.3 and 103.5 ±15.1, and full-scale IQ scores were 97.8 ± 17.3,98.4 ± 16.3 and 96.4 ± 17.4, respectively. After controlling for confounding factors, children whose mothers had highest Hb concentration were 54% (OR= 1.54,95%CI:1.13-2.11)more likely to have poor verbal scores and 53% (OR= 1.53,95%CI: 1.10-2.12)more likely to have poor full-scale scores than children whose mothers had moderate -Hb concentration. No statistical associations were noticed between high -Hb concentration and performance scores, or between low Hb concentration during early gestation and verbal, performance as well as full-scale score of pre-school children. Conclusion High maternal Hb concentration during early gestation might adversely affect children' s cognitive development.

Association between pregnancy-induced hypertension, cesarean delivery and perinatal mortality: a prospective study / 中华流行病学杂志

trimester. Conclusion Moderate and severe PIH early developed during pregnancy could increase the risk of perinatal mortality, while cesarean delivery could decrease the risks in women with PIH.

Birth weight distribution among premature infants and related social factors / 中华流行病学杂志

<p><b>OBJECTIVE</b>To understand the distribution of birth weight among premature infants and the associated social factors.</p><p><b>METHODS</b>The study population consisted of 97 537 women who delivered singleton live birth of 20 to 41 gestational weeks in 4 counties/cities, Jiangsu and Zhejiang provinces, China from 1995 to 2000. Chi-square test was employed to test the difference of proportions between respective groups. One- way ANOVA was used to test the differences regarding the mean of gestational weeks at the first prenatal visit and the mean of prenatal visits between the two groups. Multivariate logistic regression was conducted to examine the factors associated with premature birth.</p><p><b>RESULTS</b>Women aged 35 years had higher (8.8%) premature incidence than those aged less than 24 years (5.6%), 25 - 29 years (4.6%), or 30 - 34 years (4.5%, P < 0.001). Women with height less than 149 cm had higher (6.8%) premature incidence than those with height taller than 150 cm (5.0%). Women whose BMI were at least 28 and 24 - 28 had higher (5.5%, 5.5%) premature incidences than those whose BMI were 18.5 - 24.0 (5.0%), < 18.5 (4.6%, P < 0.001). The incidence of premature birth was 6.0% among women without previous pregnancy, higher than that among those women with 4 times of pregnancies (5.7%), 2 times of pregnancies (4.3%), and 3 times of pregnancies (4.0%). Parous women with at least two deliveries had higher (9.3%) premature incidence than the primiparous women (5.2%) and whose women with only one delivery (4.5%, P < 0.001). Women who received early prenatal care had lower 4.7% premature incidence than those who did not receive the service (6.1%). The mean times of prenatal visits among women with premature births was 8.53, less than that of those with full term delivery (10.97). Women with less than four times of prenatal visit had higher (18.9%) premature incidence than those with at least five prenatal visits (4.9%). Multivariate logistic regression showed that premature delivery risk was associated with age, height, BMI, gravidity, parity, early prenatal care, the mean of gestational weeks at first prenatal visit and the mean number of prenatal visits etc.</p><p><b>CONCLUSION</b>Premature delivery risk was associated with factors as age, height, BMI, gravidity, parity, early prenatal care, the mean of gestational weeks at first prenatal visit, the mean number of prenatal visits etc.</p>

The relationship between prepregnancy body mass index and the occurrence of pregnancy induced hypertension / 中华预防医学杂志

<p><b>OBJECTIVE</b>To examine the relationship between prepregnancy body mass index (BMI) and the risk of pregnancy-induced hypertension (PIH) in Chinese population.</p><p><b>METHODS</b>Data were collected in 6 counties/cities covered by Perinatal Health Care Surveillance System which was part of the Sino-American cooperative project on neural tube defects prevention established in 1992. The study population consisted of 83 159 women who attended premarital or preconception medical physical examination and delivered single live births with at least 20 gestational weeks from 1995 to 2000 in Jiaxing area. The Chi-square test was employed to test the difference in the rates of PIH among groups with different BMI. Multivariate logistic regression was conducted to examine the association between prepregnancy BMI and the risk of PIH.</p><p><b>RESULTS</b>The rate of PIH was 11.01% (9153/83 159; 95% CI: 10.79% - 11.22%). The rate of PIH among women with BMI < 18.5 kg/m(2), 18.5 - 22.9 kg/m(2), 23.0 - 24.9 kg/m(2), and > or = 25.0 kg/m(2) were 9.08% (1405/15 472; 95% CI: 8.63% - 9.54%), 10.82% (6389/59 054; 95% CI: 10.57% - 11.07%), 14.63% (943/6444; 95% CI: 13.78% - 15.52%), and 19.00% (416/2189; 95% CI: 17.38% - 20.71%), respectively, the difference was significant (chi(trend)(2) = 261.028, P = 0.000). Taking those with BMI 18.5 - 22.9 kg/m(2) as reference, the unadjusted RR for PIH was 0.82 (95% CI: 0.77 - 0.87) among women with BMI < 18.5 kg/m(2), 1.41 (95% CI: 1.31 - 1.52) among women with BMI 23.0 - 24.9 kg/m(2), and 1.93 (95% CI: 1.73 - 2.16) among women with BMI > or = 25.0 kg/m(2). After controlling for area, maternal age at delivery, educational level, occupation, parity, times of prenatal visit as well as the individual or family history of chronic hypertension, the estimated RR were 0.85 (95% CI: 0.80 - 0.90), 1.37 (95% CI: 1.27 - 1.47) and 1.88 (95% CI: 1.68 - 2.10), respectively.</p><p><b>CONCLUSION</b>High prepregnancy BMI could increase the risk of PIH.</p>

Relations between pre-pregnancy body mass index,gestational weight gain,and the occurrence of neonatal asphyxia / 中华流行病学杂志

Objective To assess the relationship between pre-pregnancy body mass index(BMI),weight gain during pregnancy,and the risk of neonatal asphyxia.Methods Data was collected in 6 counties/cities covered by Peri-natal Health Care Surveillance System which was part of a Sino-American cooperative project on neural tube defects prevention established in 1992.The study population consisted of 83 030 women who attended premarital/preconception medical physical examination program and had delivered single live birth with at least 20 gestational weeks from 1995 to 2000 in Jiaxing area,Zhejiang province.Results from the Chi-square test were employed to test the differences in the rates of neonatal asphyxia between groups with different BMI and other characteristics.Multivariate logistic regression method was conducted to examine the association between pre-pregnancy BMI,gestational weight gain,and the risk of asphyxia.Results The average rate of neonatal asphyxia was 11.3%(95% CI:11.1%-11.6%).The rates of neonatal asphyxia among women with BMI＜18.5 kg/m2,18.5-22.9 kg/m2,23.0-24.9 kg/m2,and≥25.0 kg/m2 were 11.0%(95% CI:10.5%-11.5%),11.3%(95% CI:11.1%-11.6%),11.8%(95% CI:11.0%-12.6%),and 12.9%(95% CI:11.6%-14.4%)respectively.The rates of neonatal asphyxia were 12.4% among women with weight gain＜0.3 kg/wk.higher than women with higher weight gain.After adjusting for residencial area,maternal age,educational level,occupation,parity,times of prenatal visit,high-risk experiences during pregnancy,high-risk experiences at time of delivery,gestational week and birth weight,the estimated ORs were 1.03(95% CI:0.97-1.09),1.06(95% CI:0.96-1.16)and 1.14(95% CI:1.00-1.31),respectively.These ORs became 1.02(95% CI:0.95-1.09),1.01(95% CI:0.90-1.13)and 1.08(95% CI:0.92-1.28)after further adjusting the variable "gestational weight gain".The estimated ORs for neonatal asphyxia were 1.06(95% CI:1.01-1.12)for women with weight gain at 0.3-kg/wk and 1.09(95% CI:1.02-1.20)for women with weight gain＜0.3 kg/wk when compared to those with weight gain≥0.5 kg/wk.Conclusion Lower weight gain seemed to have the effect of increasing the risk of neonatal asphyxia.

Study on anemia among premarital women in 6 counties from 1993 to 2003 / 中华流行病学杂志

<p><b>OBJECTIVE</b>To describe the prevalence of anemia and yearly trends (1993-2003) among women who came to the hospitals or maternal and child health units for premarital examinations in 6 counties of Jiangsu and Zhejiang provinces.</p><p><b>METHODS</b>Data were obtained from the records of the premarital examinations in perinatal health care surveillance system that had been established since 1992 in these areas. We reviewed hemoglobin levels of those women who were enrolled in the perinatal health care surveillance system from 1993 to 2003. Anemia was defined according to the WHO (2001) criterion. We calculated the prevalence of anemia and analyzed the yearly trends based on the data of hemoglobin concentration.</p><p><b>RESULTS</b>In the period of 1993-2003, there were 82 995 anemia cases identified among 193,434 women with an overall anemia rate as 42.9%. The rates of anemia were high (65.5%) in 1993 but low (25.8%) in 2003. 99.7% of the anemic women whose hemoglobin concentration were between 80-119.9 g/L. Time trend analysis indicated a significant decline on anemia rate while monthly analysis showed that the prevalence rates were high (48.2%) in September and low in March (39.5%). The results also showed that the prevalence rates of anemia were relatively higher in farmers and workers in rural enterprises, and lower in Han ethnicity than minorities. The higher prevalence rates of anemia were presented among the women with less education, lower body mass index, or at older age.</p><p><b>CONCLUSION</b>For those premarital women in 6 counties of Jiangsu and Zhejiang provinces, the overall anemic rate presented a significant downward trend between 1993 and 2003 while the prevalence of anemia remained high, especially for the women with less education, lower body mass index or older ages.</p>

Association of pregnancy-induced hypertension with small-for-gestational-age babies / 中华流行病学杂志

Objective To examine the association between pregnancy-induced hypertension(PIH) and small-for-gestational-age babies(SGA)in a Chinese population.Methods Subjects were women who delivered a singleton baby(gestational weeks:equal to or greater than 28,and less than 42)in four cities or counties in Jiangsu and Zhejiang provinces,China,during the period of 1995-2000.A total number of 93 743 women were included.Incidence of SGA was calculated and compared between women with or without PIH and between groups with different severities of PIH.Multiple logistic regression was used to address the relationship between PIH and SGA while controlling for maternal age,occupation,education,parity,BMI,anemia,premature rupture of membranes and fetal sex.The association between PIH and SGA was also examined according to preterm or term delivery.Results The incidence of SGA in women with PIH(6.0%)was higher than women without(4.5%),and the incidence increased with severities of PIH.The adjusted relative risk rates(95%CI)of SGA in women with mild,moderate and severe PIH were 1.17(1.01-1.34),1.69(1.33-2.14),and 3.50(2.57-4.77),respectively,when confounders were controlled for.The risk ratios of SGA in women with PIH among women who delivered a preterm baby wete higher than those among women who delivered a term baby.Conclusion There seemed a statistical association between PIH and SGA,and women with PIH having higher incidence of SGA than those withont PIH.

Study on the third trimester hemoglobin concentrations and the risk of low birth weight and preterm delivery / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate the association between third trimester hemoglobin (Hb) concentrations and the risk of low birth weight and preterm delivery in a Chinese population.</p><p><b>METHODS</b>Subjects were women who delivered in four cities/counties in Jiangsu and Zhejiang provinces, China, during the period of 1995 - 2000. Incidence of low birth weight and preterm delivery was calculated and compared among groups of women with different levels of Hb during the third trimester. Multiple logistic regression was used to address relationships between Hb levels and the risk of preterm delivery and low birth weight while controlling for potential confounding factors.</p><p><b>RESULTS</b>The overall prevalence of anemia during third trimester of pregnancy was 48.2% , mainly consisting of mild and moderate anemia. Mild and moderate anemia did not increase the risk of preterm delivery and low birth weight statistically. The lowest incidence of preterm delivery and low birth weight was found among pregnant women with Hb levels at 90-99 g/L. The risk for preterm delivery and low birth weight increased with either increasing or decreasing hemoglobin concentrations. However,there was no remarkable elevation of the risk when Hb was in the range of 70-119 g/L. Women with severe anemia (Hb< 70 g/L) had 80% higher risk (95% CI:1.0-3.3) of preterm delivery and a 4.0-fold higher risk (95 % CI :2. 1-7.5) of low birth weight compared with women with an Hb value of 90-99 g/L. In addition, women with a high Hb concentration (Hb> 130 g/L) had 20% higher risk (95 % CI: 1..0-1.4) of preterm delivery and 50 % higher risk (95 % CI: 1.2-1.9) of low birth weight.</p><p><b>CONCLUSION</b>A U-shape relationship was found between Hb concentration and the risk of preterm delivery and low birth weight. Severe anemia and high hemoglobin concentration were both associated with increased risk of preterm deliveries and low birth weight.</p>

Prevalence of preterm birth among singletons in 10 counties (cities) of China, 1993-2005 / 中华流行病学杂志

<p><b>OBJECTIVE</b>To describe the secular trends and epidemiological characteristics of preterm birth among singletons in 10 counties (cities) of China during 1993-2005.</p><p><b>METHODS</b>We analyzed data on 542 923 women (gestational age > or =28 weeks) collected through Perinatal Healthcare Surveillance System established by the Institute of Reproductive and Child Health, Peking University. Chi-square tests were employed to test the differences in prevalence of preterm birth among different groups.</p><p><b>RESULTS</b>25 784 preterm births were identified, including 1530 stillbirths. Preterm birth rate was 4.75% (95% CI:4.69-4.81) for all births and 4.49% (95% CI:4.44-4.55) for live births. Preterm birth rate declined steadily from 1993 to 2005 and had no significant seasonal variation. Preterm birth rate from the urban areas of the Southern part of the country,was higher than that in the rural areas which was also higher than that seen in the rural areas from the northern part of the country. Relations between women's age at delivery and preterm birth appeared to be U-shaped. Increased preterm birth rates were also observed in women with lower education level,more parities,and previous history of preterm birth or abortion.</p><p><b>CONCLUSION</b>Preterm birth rate decreased steadily from 1993-2005 in 10 counties (cities) but varied by areas of the country.</p>

The current status and the changing patterns of perinatal health care in some southern and northern areas of China, 1994 - 2000 / 中华流行病学杂志

<p><b>OBJECTIVE</b>To understand the current status and its changing patterns of perinatal health care in some southern and northern areas of China from 1994 to 2000.</p><p><b>METHODS</b>Data was collected in 13 counties/cities covered by Perinatal Health Care Surveillance System which was part of the Sino-American cooperative project on neural tube defects prevention, established in 1992. The study population consisted of 368 589 women who delivered single live births of at least 20 gestational weeks from 1994 through 2000. Chi-square test was employed to test the difference on the proportions of women with prenatal checkup, women with early prenatal care onset, women with at least five prenatal visits, hospital delivery versus home delivery as well as the proportion of women with at least three postpartum visits. Two-way ANOVA was used to test the differences of mean of gestational weeks at first prenatal visit and the mean of prenatal visits between different year and areas.</p><p><b>RESULTS</b>The proportion of women with prenatal checkup remained over 99.0% from 1994 through 2000. The mean of gestational weeks at first prenatal visit changed from 13.1 weeks in 1994 to 10.7 weeks in 2000. The proportions of women with early prenatal care onset increased from 65.5% in 1994 to 79.4% in 2000 while women with at least five prenatal visit increasing from 34.1% to 71.8%, hospital delivery increasing from 91.3% to 98.8%, home delivery decreasing from 5.6 % to 0. 6%, women with at least three postpartum visits increasing from 80.5 % to 95.1%. Except for the proportion of women with early prenatal care onset, other proportions in northern areas were lower than those in southern areas in the same year. Greater differences between urban and rural areas in northern areas were found than in southern areas.</p><p><b>CONCLUSION</b>The utilization of perinatal health care services was greatly improved in both southern and northern areas from 1994 to 2000. However, there were still obvious differences in the perinatal health care services between northern and southern areas as well as between urban and rural areas in northern China.</p>