Cesarean delivery on maternal request and common child health outcomes: A prospective cohort study in China.

Background: Cesarean delivery vs vaginal delivery was reported to increase the risks of childhood obesity, pneumonia, anemia, and neurobehavioral disorders, but few studies were able to deal with the confounding biases associated with medical conditions indicating cesareans. This prospective cohort study aims to investigate the associations of non-medically indicated cesarean delivery on maternal request (CDMR) with these child health outcomes. Methods: Among 17 748 liveborn infants whose mothers (primiparas) participated in a randomized controlled trial on micronutrient supplementation and pregnancy outcomes during 2006-2009 in 5 rural counties in Hebei Province, China, 6972 singletons born by full-term spontaneous vaginal delivery (SVD) and 3626 by CDMR were extracted for the assessments of obesity (weight-for-height z-score >3) and pneumonia (self-reported) at 1.5-5 years in 2011. Some children were further randomly selected from these two groups for the assessments of anemia (hemoglobin <110 g/L, 2341 SVD and 2417 CDMR) and neurobehavioral disorders (raw score of Child Behavior Checklist larger than the 90th percentile of the normative sample, 1257 SVD and 1060 CDMR). Results: Compared with SVD, CDMR was associated with increased risks of obesity (adjusted odds ratio (aOR) = 1.41, 95% confidence interval (CI) = 1.14-1.75, P = 0.002) and anemia (aOR = 1.65, 95% CI = 1.28-2.12, P < 0.001), but not with the risk of pneumonia (aOR = 1.16, 95% CI = 0.94-1.45, P = 0.17) or neurobehavioral disorders (aORs varied from 0.82 to 0.91, P > 0.05) in childhood. Conclusions: Cesarean delivery, independent of cesarean indications, is likely associated with childhood obesity and anemia, indicating a need to keep pregnant women informed, especially those seeking CDMR, a need to explore possible improvement on obstetric service, and even a need for main stakeholders to reach a compromise in making a cesarean decision. Trial registration: ClinicalTrials.gov: NCT00133744 and NCT01404416.

Association of cesarean delivery with anemia in infants and children in 2 large longitudinal Chinese birth cohorts.

BACKGROUND: Cesarean delivery may reduce placental-fetal transfusion and thus increase the risk of early childhood anemia compared with vaginal delivery, but this notion has not been carefully studied in longitudinal cohorts. OBJECTIVE: The aim was to assess the association of cesarean delivery with anemia in infants and children in 2 longitudinal Chinese birth cohorts from different socioeconomic settings. DESIGN: Cohort 1 was recruited from 5 counties in northeastern China and cohort 2 from 21 counties or cities in southeastern China. Cohort 1 involved 17,423 infants born during 2006-2009 to mothers with early pregnancy baseline hemoglobin concentrations ranging from 100 to 177 g/L, whereas cohort 2 involved 122,777 children born during 1993-1996 to mothers with baseline hemoglobin concentrations ranging from 60 to 190 g/L. The main outcomes were anemia at 6 and 12 mo in cohort 1 and at 58 mo in cohort 2. Multiple logistic regressions were used to estimate adjusted ORs of anemia for cesarean compared with vaginal delivery. Stratified analyses were performed by pre- and postlabor cesarean delivery and according to maternal baseline hemoglobin concentration (≤109, 110-119, 120-129, and ≥130 g/L). RESULTS: Cesarean delivery was not associated with anemia at 6 mo in cohort 1 (adjusted OR: 1.05; 95% CI: 0.93, 1.19); however, cesarean delivery was associated with increased anemia at 12 mo in cohort 1 (adjusted OR: 1.19; 95% CI: 1.04, 1.37) and at 58 mo in cohort 2 (adjusted OR: 1.11; 95% CI: 1.08, 1.15). The positive associations for anemia at 12 and 58 mo were consistent across maternal hemoglobin subgroups and persisted for cesarean delivery subtypes. CONCLUSION: Cesarean delivery is likely associated with anemia in children, which suggests a possible need for exploring changes in obstetric care that might prevent anemia in cesarean-delivered children.

[Establishment and evaluation of enzyme-linked immunosorbent assay for measuring human IgM autoantibody to folate receptor].

OBJECTIVE: To establish the method of enzyme-linked immunosorbent assay (ELISA) for measuring human IgM autoantibody to folate receptor. METHODS: 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. RESULTS: 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). CONCLUSIONS: The folate receptor-ELISA method for measuring human IgM autoantibody to folate receptor was successfully established. The method is sensitive, repeatable, and stable.

[Impact of pregnancy terminations before 28 weeks of gestation on the overall prevalence of neural tube defects in two counties of Shanxi province].

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 Taigu 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 prevalence 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 pregnancies≥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.

BACKGROUND: 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. METHODS: 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. RESULTS: 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). CONCLUSION: Maternal periconceptional consumption of pickled vegetables may increase the risk for NTDs in Shanxi Province.

Cesarean delivery on maternal request and childhood intelligence: a cohort study.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: Neither cesarean delivery on maternal request nor assisted vaginal delivery affected children's IQ.

[Questionnaire-based survey of allergic diseases among children aged 0 - 14 years in the downtown of Beijing, Chongqing and Guangzhou].

OBJECTIVE: 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. METHOD: 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. RESULT: 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. CONCLUSION: 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.

[Analysis on influencing factors for stunting and underweight among children aged 3 - 6 years in 15 counties of Jiangsu and Zhejiang provinces].

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 status of pregnant mothers should be improved to promote the growth level of preschool children.

[Study on the current status of spontaneous abortion of primigravid women in Jiaxing of Zhejiang province, China].

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.

[Correlation on hemoglobin concentration and the development of cognition among pre-school children].

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 Zhejiang 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 1.4-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 /= 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 95.9 +/- 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].

OBJECTIVE: To determine the association between pregnancy-induced hypertension(PIH) and risk of preterm delivery (PD) and low birth weight (LBW). METHODS: 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). RESULTS: 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). CONCLUSION: PIH could increase the incidence of PD and LBW.

[Influence of hemoglobin level during early gestation on the development of cognition of pre-school children].

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, 104.5 ± 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.

Current trends of the prevalence of childhood asthma in three Chinese cities: a multicenter epidemiological survey.

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: The prevalence of childhood asthma is statistically higher than that 10 years ago in the three Chinese cities.

[The relationship between prepregnancy body mass index and the occurrence of pregnancy induced hypertension].

OBJECTIVE: To examine the relationship between prepregnancy body mass index (BMI) and the risk of pregnancy-induced hypertension (PIH) in Chinese population. METHODS: 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. RESULTS: 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. CONCLUSION: High prepregnancy BMI could increase the risk of PIH.

[Association between pregnancy-induced hypertension, cesarean delivery and perinatal mortality: a prospective study].

OBJECTIVE: To examine the relationship between pregnancy-induced hypertension (PIH) and risks of perinatal mortality. METHODS: A population-based, retrospective cohort study was conducted based on 134 858 women registered in a perinatal health care surveillance system and delivered singleton births between 1995 to 2000 in Zhejiang province, China. Multivariate logistic regression models were employed to estimate the relative risk (OR) and 95%CI. RESULTS: The perinatal mortality rate (95%CI) was 7.6 per thousand (7.1 - 8.1) in normotensive women and 9.2 per thousand (7.7 - 10.8) in PIH women. The cesarean delivery rate was 45.7% in normotensive women and 55.7% in groups with PIH. When compared with the normotensive women, the unadjusted OR (95%CI) for perinatal mortality was 1.21(1.01 - 1.46) in groups with PIH; 0.97 (0.77 - 1.22) in groups with mild PIH, 1.73 (1.26 - 2.37) in groups with moderate PIH, and 2.01 (1.18 - 3.43) in groups with severe PIH; 0.99 (0.77 - 1.26) in groups with PIH developed before delivery, 1.39 (1.05 - 1.84) in groups with PIH developed in second trimester, and 2.69 (1.54 - 4.69) in groups with PIH developed in third trimester. After controlling for maternal age, occupation, educational attainment, parity, times of prenatal visit, infant's sex, pregnancy complications and cesarean delivery, the OR (95%CI) for perinatal mortality was 1.09 (0.90 - 1.31) in women with PIH when compared with the normotensive groups. The adjusted OR for perinatal mortality was 0.81 (0.64 - 1.02) in groups with mild PIH, 1.94 (1.41 - 2.67) in groups with moderate PIH, and 3.32 (1.92 - 5.75) in groups with severe PIH; 0.82 (0.63 - 1.05) in groups with PIH developed before delivery, 1.51 (1.14 - 2.00) in groups with PIH in second trimester, and 2.67 (1.52 - 4.70) in groups with PIH in third 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].

OBJECTIVE: To understand the distribution of birth weight among premature infants and the associated social factors. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

[Relations between pre-pregnancy body mass index, gestational weight gain, and the occurrence of neonatal asphyxia].

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 countiedeities 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 > or = 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 residential 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 > or = 0.5 kg/wk. CONCLUSION: Lower weight gain seemed to have the effect of increasing the risk of neonatal asphyxia.

[Association of pregnancy-induced hypertension with small-for-gestational-age babies].

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 were 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 without PIH.