[Association between prenatal exposure to PM2.5 and fetal growth: a prospective cohort study].

Objective: To investigate the association of exposure to PM2.5 and its constituents during pregnancy and fetal growth and to further identify critical windows of exposure for fetal growth. Methods: We included 4 089 mother-child pairs from the Jiangsu Birth Cohort Study between January 2016 and October 2019. Data of general characteristics, clinical information, daily average PM2.5 exposure, and its constituents during pregnancy were collected. Fetal growth parameters, including head circumference (HC), abdominal circumference (AC), and femur length (FL), were measured by ultrasound after 20 weeks of gestation, and then estimated fetal weight (EFW) was calculated. Generalized linear mixed models were adopted to examine the associations of prenatal exposure to PM2.5 and its constituents with fetal growth. Distributed lag nonlinear models were used to identify critical exposure windows for each outcome. Results: A 10 µg/m3 increase in PM2.5 exposure during pregnancy was associated with a decrease of 0.025 (ß=-0.025, 95%CI: -0.048- -0.001) in HC Z-score, 0.026 (ß=-0.026, 95%CI: -0.049- -0.003) in AC Z-score, and 0.028 (ß=-0.028, 95%CI:-0.052--0.004) in EFW Z-score, along with an increased risk of 8.5% (RR=1.085, 95%CI: 1.010-1.165) and 13.5% (RR=1.135, 95%CI: 1.016-1.268) for undergrowth of HC and EFW, respectively. Regarding PM2.5 constituents, prenatal exposure to black carbon, organic matter, nitrate, sulfate (SO42-) and ammonium consistently correlated with decreased HC Z-score. SO42- exposure was also associated with decreased FL Z-scores. In addition, we found that gestational weeks 2-5 were critical windows for HC, weeks 4-13 and 19-40 for AC, weeks 4-13 and 23-37 for FL, and weeks 4-12 and 20-40 for EFW. Conclusions: Our findings demonstrated that exposure to PM2.5 and its constituents during pregnancy could adversely affect fetal growth and the critical windows for different fetal growth parameters are not completely consistent.

[Mediation effect of smoking and healthy diet score on the association between educational level and the risk of lung cancer incidence].

Objective: To evaluate the possible mediation effect of smoking and healthy diet score on the association between educational level and the risk of lung cancer incidence. Methods: After excluding individuals with missing educational levels and cancer information at baseline, 446 772 participants in the UK Biobank (UKB) prospective cohort study were included. Cox regression models were used to investigate the associations of educational level and smoking and healthy diet score with the incidence of lung cancer. Mediating effect analysis was conducted to analyze the mediating effect of smoking and healthy diet score on the correlation between educational level and lung cancer. Results: During a median follow-up of 7.13 years, 1 994 new- onset lung cancer cases were observed. Per 1 standard deviation (5 years) increase in educational level was associated with a 12% lower risk of lung cancer (HR=0.88, 95%CI: 0.84-0.92). The corresponding level 1-5 in the International Standard Classification for Education (ISCED) were mapped to UKB self-report highest qualification to estimate the educational level. A higher rank means a higher educational level. Compared with level ISCED-1, the HR(95%CI) of level ISCED-2, ISCED-3, ISCED-4 and ISCED-5 were respectively 0.83 (0.72-0.94), 0.67 (0.53-0.85), 0.76 (0.65-0.89) and 0.72 (0.64-0.80) for lung cancer. Education years were negatively correlated with smoking, with ß coefficients (95%CI) being -0.079 (-0.081- -0.077), but positively correlated with healthy diet score (ß=0.042, 95%CI: 0.039-0.045). Analysis of mediating effect indicated that the association of educational level with lung cancer risk was mediated by smoking and healthy diet score, the proportions of mediating effect were 38.952% (95%CI: 31.802%-51.659%) and 1.784% (95%CI: 0.405%-3.713%), respectively. Conclusion: Smoking and healthy diet score might mediate the effect of educational level on the incidence of lung cancer, indicating that improving the level of education can reduce the risk of lung cancer by changing lifestyles such as smoking and diet.

Mass oscillations and matter wave's phase and amplitude modulations of relativistic quantum particles induced by Heisenberg's uncertainty principle.

We present a flip-flop dual-component model to treat quantum dynamics of relativistic particles with a rest mass and investigate the matter waves' phase and amplitude modulations due to Heisenberg's uncertainty principle. Their matter waves behave like a traveling Gaussian-shaped wave packet accompanied by a guiding pilot wave, and the phase modulations result in mass oscillations. These effects are more prominent for light-weighted elementary particles, such as neutrinos and electrons. This mechanism is solely due to the uncertainty principle and has nothing to do with the flavor-mixing of neutrinos. Simulations using neutrinos and electrons are presented, which indicate an oscillation period on the order of ps. This study primarily focuses on the predicted mass oscillations induced by the uncertainty principle. A slit-type interference experiment using neutrinos and electrons from reactors is proposed to test the predicted behaviors.

[Polygenic risk score in personalized screening of lung cancer: a prospective cohort study in Chinese].

Objective: To explore how to personalize lung cancer screening programs for prevention in Chinese populations based on individual genetic risk score. Methods: We constructed the lung cancer polygenic genetic risk score (PRS-19) based on the 19 previously published genetic variations, using 100 615 participants with genotyping data from the China Kadoorie Biobank (CKB). Using the 5-year absolute risk of lung cancer in a population (55 years old with at least 30-pack-year history of smoking) as reference, the trend of 5-year absolute risk in different genetic risk groups was calculated in smokers and non-smokers, respectively. Distribution curves of 5-year absolute risk were also described to determine the theoretical age or smoking dose when different genetic risk groups reached the reference values. Given the overall findings, the specific start age for lung cancer screening were suggested for different genetic risk groups. Results: The 5-year absolute risk of lung cancer was 0.67% in 55-year-old smokers with 30 packs per year in the CKB. Among smokers, 5-year absolute risk of participants increased as the genetic risk increased. Hence, it was recommended that people at high genetic risk should start screening earlier. For the highest genetic risk populations (the top 1% of PRS), the start age might be changed to 50 years old. If the start age remained at 55-year-old, the smoking dose should be set lowered in high genetic risk populations. For the highest genetic risk populations, they should be included in lung cancer screening regardless of the cumulative smoking exposure. Among nonsmokers, it was also valuable to screen people with high genetic risk, considering the start age of 62 for the highest genetic risk populations and 74 for the lowest genetic risk populations (the bottom 5% of PRS). Conclusions: PRS-19 can be effectively used in developing lung cancer screening program for individualized prevention in China. For smokers with high genetic risk, the recommended starting age and smoking dose could be lowered for lung cancer screening, and non-smokers with high genetic risk could also be included in the screening programs.

[Profile of China National Birth Cohort].

With the rapid changes in lifestyle, natural and social environment, the reproductive health status of couples in childbearing age continues to decline, and long-term outcomes of the rapidly increasing offspring conceived by assisted reproductive technology (ART) needs to be evaluated urgently. Therefore, the focus of research now needs to be extended from death and severe diseases to full life cycle and full disease spectrum. In order to meet the demand for such research, we launched the China National Birth Cohort (CNBC) study, an ongoing prospective and longitudinal study aiming to recruit 30 000 families underwent ART and 30 000 families with spontaneous pregnancies. Long-term follow-up programs will be conducted for both spouses and their offspring. Data of couples and their offspring, such as environmental exposure, reproductive history, psychological and behavioral status, will be collected during follow-up. Peripheral blood, urine, umbilical blood, follicular fluid, semen were also collected at different follow-up nodes. Based on high-quality data and biological samples, CNBC will play an extremely important supporting role and have a far-reaching impact on maternal and children's health care and reproductive health in China. This paper is exactly a brief introduction to the construction and basic design of CNBC.

[Quality control and measures of China National Birth Cohort].

Birth cohort is an effective method to explore the relationship between various prepregnant and pregnant exposures and the health of fetuses, infants and young children. It is a long construction period to build a birth cohort and the quality of research may be affected by many factors. This paper reviews the quality assurance and quality control measures in the process of China National Birth Cohort (CNBC), and summarizes the construction experience. We aim to provide experience for related cohort studies, which could improve the quality of cohort studies through removing the impact of related factors. CNBC adopted a series of measures to ensure the quality of research in the top-level design of quality assurance, including screening research center, developing member management system, formulating standard operating procedures and training staff by it. In terms of quality control, it includes real-time, timely and timing quality control for the process of data generation, full-cycle quality control for biological sample collection, processing, storage and comprehensive three-dimensional quality control for staff training, supervision and quantitative assessment.

[Baseline characteristics of the participants of China National Birth Cohort].

Objective: To explore the effects of environmental, genetic factors as well as the interactions in early life on the short-term and long-term health of offspring and to systematically evaluate the pregnancy outcomes and health of offspring after birth between families with assisted reproductive technology (ART) conception and families with spontaneous conception. Methods: The China National Birth Cohort (CNBC), a multicenter prospective birth cohort study, includes both families with ART conception and families with spontaneous conception. Since 2016, CNBC has recruited families from 24 hospitals located in 12 provinces, municipalities and autonomous regions throughout China. Information and biospecimens were collected before ART treatment, embryo transfer, at early, second, third trimester and delivery, and at 42 days, 6, 12 and 36 months after birth. Results: By June 2020, CNBC had included 27 044 families with ART conception and 29 589 families with spontaneous conception. The majority of the participants are urban residents. Among the families with ART conception, 65.5% of the men and 63.7% of the women had college degrees or higher. The mean age distribution of men and women was (33.83±5.52) and (32.38±4.67) years. 83.2% of women were primiparas, and the prevalence rates of current regular smokers and current alcohol drinkers were 0.8% and 2.1% in women. Among the families with spontaneous conception, 81.5% of the men and 86.5% of the women had college degrees or higher. The mean age distribution of men and women was (32.06±5.09) and (30.40±4.27) years. 67.2% of women were primiparas, and the prevalence rates of current regular smokers and current alcohol drinkers were 0.1% and 2.2% in women. The baseline characteristics were different between the families with ART conception and spontaneous conception in different regions. Conclusion: CNBC provides a powerful and rich resource in studying the impact of genetic, environmental factors and interactions in early life and ART treatment on the health of offspring after birth.

[Application of cloud-based information platform in China National Birth Cohort].

Birth cohort is an important observational study which can continuously and dynamically collect the exposure changes and health outcomes from gametophyte development to adolescence and even old age. However, because of its complex design and difficult implementation, how to construct birth cohort with high quality and high efficiency is the main difficulty faced by epidemiologists at home and abroad. In 2016, China National Birth Cohort was officially launched. The network and information technology were used to explore, and a set of "cloud-based information platform" was established to support this queue construction, containing 16 units in China. After four years of development, the platform has formed a complete set of programs about the construction of cohort information platform, which including recruitment and follow-up management of participants, real-time data interaction, queue quality control, multi-level authority management and function division. The relevant design framework and functional elements provide the references to the future information construction of large-scale birth cohort and even population-based research in China.

[The Autism Spectrum Disorder Cohort-the sub-cohort of China National Birth Cohort].

Autism spectrum disorder (ASD), a representative disease of children's neurodevelopmental disorders, brings huge pressure and financial burden to families and society. It is of great significance to explore its etiology and pathogenesis. Therefore, we established an ASD Cohort based on the existing China National Birth Cohort (CNBC), which applied parallel design to recruit and follow up families who achieved pregnancy after receiving assisted reproductive technologies (ART) and families with spontaneous conception. The main aims of this study are to compare the incidence of ASD among children born after ART with those born under spontaneous pregnancy, and to evaluate the impact of ART on the neurobehavioral development of offspring. Additionally, with a variety of clinical and behavioral related information collected during pregnancy and at early life of offspring, we are able to investigate the risk factors associated with ASD comprehensively. This article briefly introduces the objectives, contents, preliminary progress, strength and limitations, as well as further prospects of the ASD cohort study, mainly focusing on the overall design and current progress.

[A sub-cohort study design of the maternal and infant microbes in China National Birth Cohort].

The importance of gut microbes to human health has gradually attracted attention. With the use of animal models, it has been revealed that maternal microbes during pregnancy could influence their children's health outcomes through shaping their microbial composition and regulating the development of their metabolic and immune system. However, the physiological mechanism of the human body is more complex and is affected by the interaction of multiple factors. The research results obtained from animal models are often inconsistent with human studies. At present, the influence of maternal intestinal microbes during pregnancy on the microbial colonization in their offspring and on a series of children's health outcomes is still unclear. Establishing a sub-cohort to detect the microbiome of the women across pregnancy and of their offspring, and further to integrate with variety of environmental and behavioral exposures can better provide reliable support for the research on the mechanism of children's health and diseases. This paper briefly introduces the research objectives, content, progress, strength and limitations of the sub-cohort study.

[Association between polygenic risk score and age at onset of gastric cancer].

Objective: To explore the association between polygenic risk score (PRS) and age at onset and early-onset risk of gastric cancer (GC). Methods: Gastric cancer cases from existing genome-wide association study were included, and 112 single nucleotide polymorphisms associated with GC risk were used to derive individual PRS. Analysis of variance and Pearson correlation test was used to depict the relationship between PRS and GC onset age. Cases diagnosed before 50 years old were defined as early-onset gastric cancer. Cox proportional hazard model was used to test the association between PRS and early-onset GC risk with early-onset age as the timescale and low genetic risk (PRS ≤20%) as the reference group. Results: A total of 8 629 cases, including 6 284 males (72.82%) and 2 345 females (27.18%), were included, and the mean age was (60.61±10.80) years old. The PRS was negatively correlated with age of GC onset (r=-0.05, P<0.001). The mean age of gastric cancer cases with low, intermediate, and high genetic risk were (61.68±10.33), (60.53±10.79), (59.80±11.20), respectively. PRS was significantly associated with the risk of early-onset GC in a dose-response manner (intermediate genetic risk: HR=1.19, 95%CI: 1.03-1.39, P=0.022; high genetic risk: HR=1.44, 95%CI: 1.20-1.71, P<0.001). Conclusions: PRS may contribute to the risk of both GC and early-onset GC. PRS can be used as a measurable indicator for risk prediction for occurrence and early-onset of GC.

[Epidemiological research in the big data era: opportunities, challenges and prospectives].

Recent years with the rapid progress in high-throughput omics techniques, the accumulation of population cohorts and biobanks, great advances in internet and information technology, and the emerging tools for big data utilization, health care big data provide abundant data resources and broad research platforms for epidemiological research. We aimed to review the opportunities and challenges of epidemiological research in the era of big data, and explore the future development of epidemiology. Epidemiology should seize the opportunities, open up new directions, develop new methods, and promote the translation of research results into public health and clinical medicine, which will eventually realize the vision of "Healthy China".

[Effects of estradiol on the day of human chorionic gonadotropin administration on adverse perinatal outcomes].

Objective: To investigate the association between estradiol on the day of human chorionic gonadotropin (HCG) administration and birth outcomes among singleton live births following fresh embryo transfers. Methods: Based on the clinical reproduction medicine management system of the First Affiliated Hospital of Nanjing Medical University, this retrospective cohort study collected data of fresh embryo transfer cycles during January 2013 and December 2016, including pregnant women's age, body mass index (BMI), type and cause of infertility, assisted reproductive therapy indicators (fertilization mode, ovulation stimulation protocol, estradiol levels on HCG administration day), adverse birth outcomes[small for gestational age (SGA), premature and low birth weight (LBW)], etc.. A total of 2 060 women with singleton pregnancy (2 061 fresh embryo transfer cycles) were enrolled. Multivariate logistic regression was used to analyze the association between estradiol on HCG administration day and singletons' adverse birth outcomes. Results: The age and BMI of the 2 060 pregnant women were (29.63±3.92) years old and (22.29±2.86) kg/m2. Incidences of SGA, premature and LBW were 9.8% (201/2 061), 6.9% (143/2 061) and 3.5% (73/2 061), respectively. After adjusting for confounders, the risk of LBW in 4 000-4 499 pg/ml group was significantly elevated when compared to estradiol<1 500 pg/ml group [OR (95%CI): 4.42 (1.13-17.24)]. A protective effect of premature was observed in estradiol≥4 500 pg/ml group [OR (95%CI): 0.50 (0.25-0.97)]. Conclusion: The high level of estradiol on HCG administration day might be a risk factor for LBW, but a protective factor for premature.

[Observation and analysis of systemic reactions to house dust mite subcutaneous immunotherapy in 362 patients with allergic rhinitis].

Objective: To investigate the frequency and severity of systemic reactions (SRs) to standardized house dust mite subcutaneous immunotherapy (SCIT) in patients with perennial allergic rhinitis (AR), and to analyze the clinical risk factors. Methods: The clinical data of 362 patients including 209 males and 153 females, aged from 5 to 55 years old receiving SCIT at the Department of Otorhinolaryngology, the Third People's Hospital of Changzhou were collected from May 2014 to July 2017. The SRs were classified as early-onset and delayed-onset, and 4 grades (grade Ⅰ to Ⅳ) to assess severity. The records of SRs were retrospectively analyzed, including the numbers/frequencies, symptoms and signs, onset of reaction and treatment. And the relationships between SRs and patient's age, gender, allergen injection dose, accompanied allergic diseases were explored. All the statistical analyses were conducted using SPSS 19.0. Results: There were 57 cases (15.75%) of SRs in 362 patients. All the patients received a total of 12 308 injections and 111 SRs (0.90%) were observed. Among them, 31 (27.93%) were early-onset reactions and 80 (72.07%) were delayed-onset reactions; most of the SRs were grade Ⅰ reactions (n=83, 74.78%), followed by grade Ⅱ (n=25, 22.52%), grade Ⅲ (n=3, 2.70%), and no fatal reactions occurred. The incidence of SRs in patients>14 years old was higher than that in patients ≤14 years old according to the number of cases and injections (35.14% vs 13.54%, 2.34% vs 0.76%, χ(2) value was 11.679, 28.162, respectively, all P<0.05), but no significant differences of SRs were observed in gender (18.66% vs 11.76%, 5.98% vs 5.62%, χ(2) value was 3.166, 0.095, respectively, all P>0.05). Fifteen SRs (13.51%) occurred during the build-up phase and 96 (86.49%) during the maintenance phases. SRs could occur in lots of dose phases, and 95 (85.59%) were distributed at high concentrations more than 40 000 SQ-U. The incidence of SRs in patients with multiple allergic diseases was significantly higher than that in patients with AR alone, with asthma or atopic dermatitis (30.67% vs 11.85%, χ(2)=15.875, P<0.001). Meanwhile, the incidence of SRs in patients with pure AR was also significantly lower than that in patients with other allergic diseases (5.26% vs 20.56%, χ(2)=13.783, P<0.001). Conclusions: The incidence of SRs is less than 1% according to the injection times, the severity of SRs is mostly slight, and the safety and tolerance are good during standardized house dust mite SCIT in perennial AR patients. Delayed-onset SRs are more common. The incidence of SRs is significantly correlated with age, high dose of allergen vaccine injection, and concomitant other allergic diseases (asthma, atopic dermatitis, etc).

[Screening and management of asymptomatic infection of 2019-novel coronavirus].

At present, the prevention and control of COVID-19 in China has entered a critical period. Recently, various areas outside Hubei Province have gradually begun to resume work and production, but the development of the epidemic situation is still uncertain and complex. A few days ago, researchers gradually began to pay attention to asymptomatic infection of 2019-novel coronavirus and described the disease process of asymptomatic infection and the possibility of being a source of infection. This provided a scientific basis for further optimizing and improving epidemic prevention and control measures. Paying attention to the screening and self-protection of high-risk groups and strengthening the level of detection should be helpful to the detection and management of asymptomatic infection.

[Thoughts on the reform of preventive medicine education in the context of new medicine].

Talent training is the core and foundation of public health system construction. Shortage of talents in the field of disease prevention and public health exposed by COVID-19 pandemic highlights the importance of developing preventive medical education. This article analyzes the challenges of medical education in the dilemma of "separation of medical treatment and prevention", and the new requirements for preventive medical education in the construction of New Medicine under the Healthy China strategy. Four aspects including stepping up the resource allocation and investment, educating responsible public health professionals, the education of all medical students who implement the core competence of public health, and the establishment of a continuing education system for preventive medicine have been considered. A series of specific suggestions are put forward including the establishment of a full-chain closed-loop research system to support the cultivation of top-notch innovative public health talents, strengthening the assessment of core public health capabilities for clinical medical professional admission, formulating a "medical and preventive integration" training program for primary health personnel, and implementing "combination of peace and war" public health personnel reserve system, with the purpose of providing reference for the reform and development of preventive medical education in China.

[Estimation on the individual treatment effect among heterogeneous population, using the Causal Forests method].

Objective: This project aimed to explore the effectiveness of estimating individual treatment effect on real data, among the heterogeneous population, with Causal Forests (CF) method, to find out the characteristics of heterogeneous population. Methods: We designed and conducted four computer simulation schemes to verify the effect of estimating on individual treatment, using the CF under four different environments of the treatment effects. Real data was then analyzed for the catheterization on right heart. Results: Results from the simulation process showed that the values on individual treatment effect that were estimated by causal forests were consistent with the population effect as well as in line with the expected distribution under the setting of four different effect values. Results of real data analysis showed that values of individual treatment effect among most patients appeared positive, so the use of RHC could cause an increase of the '180-day mortality rate' in the sampled population. Patients with lower predicted probability of 2-mo survival and albumin were more likely to have a lower risk of death after using the RHC. Conclusion: CF method could be effectively used to estimate the individual treatment effect and helping the individuals to make decision on the receipt of treatment.

[Study on genetic structure differences and adjustment strategies in different areas of China].

Objective: To describe the genetic structure of populations in different areas of China, and explore the effects of different strategies to control the confounding factors of the genetic structure in cohort studies. Methods: By using the genome-wide association study (GWAS) on data of 4 500 samples from 10 areas of the China Kadoorie Biobank (CKB), we performed principal components analysis to extract the first and second principal components of the samples for the component two-dimensional diagram generation, and then compared them with the source of sample area to analyze the characteristics of genetic structure of the samples from different areas of China. Based on the CKB cohort data, a simulation data set with cluster sample characteristics such as genetic structure differences and extensive kinship was generated; and the effects of different analysis strategies including traditional analysis scheme and mixed linear model on the inflation factor (λ) were evaluated. Results: There were significant genetic structure differences in different areas of China. Distribution of the principal components of the population genetic structure was basically consistent with the geographical distribution of the project area. The first principal component corresponds to the latitude of different areas, and the second principal component corresponds to the longitude of different areas. The generated simulation data showed high false positive rate (λ=1.16), even if the principal components of the genetic structure was adjusted or the area specific subgroup analysis was performed, λ could not be effectively controlled (λ>1.05); while, by using a mixed linear model adjusting for the kinship matrix, λ was effectively controlled regardless of whether the genetic structure principal component was further adjusted (λ=0.99). Conclusions: There were large differences in genetic structure among populations in different areas of China. In molecular epidemiology studies, bias caused by population genetic structure needs to be carefully treated. For large cohort data with complex genetic structure and extensive kinship, it is necessary to use a mixed linear model for association analysis.

[Analysis on factors related to spontaneous reduction in twin pregnancy following assisted reproductive technology].

Objective: To explorer factors related to spontaneous reduction in twin pregnancy following assisted reproductive technology. Methods: 2 848 twin pregnant women with treatment of vitro fertilization-embryo transfer (IVF-ET) or intra cytoplasmic sperm injection (ICSI) cycles were enrolled at Assisted Reproductive Centre of the First Affiliated Hospital of Nanjing Medical University, Nanjing Maternity Hospital and Shengjing Hospital of China Medical University from January 2013 to December 2016 respectively. Basic features of subjects, relevant clinical indicators, factors of assisted reproductive therapy and pregnancy outcome were collected from clinical assisted reproductive technology management system. According to the pregnancy outcome, the subjects with spontaneous reduction were classified as case group (n=686), and those with normal twin birth were classified as control group (n=2 162). The features of subjects in the two groups were compared. Non-conditional logistics regression model was used to analyze the related factors of the occurrence of spontaneous reduction. Results: The age of case group and control group were (30.6±4.3) and (30.2±4.0) years old respectively. After the adjustment of male sterile factor, compared to the subjects with luteinizing hormone level on the day of human chorionic gonadotropin administration (HCG) <1.43 IU/L, OR (95%CI) of the subjects with value at 2.59-5.10 IU/L was1.62 (1.08-2.42).Compared to the subjects with number of transferred embryo as 1, OR (95%CI) of the subjects with value as 3 was 0.23 (0.07-0.74). Compared to the subjects with stage of transferred embryo as cleavage stage, OR (95%CI) of the subjects with blastula stage was 0.42 (0.27-0.67). Conclusion: Luteinizing hormone level on day of HCG, number and stage of embryo transfer are related factors to spontaneous reduction in twin pregnancy following assisted reproductive technology.