中国成年双生子饮茶行为分布特征

目的 描述中国双生子登记系统（CNTR）成年双生子饮茶行为的分布特征,探索饮茶行为在双生子人群中的分布规律,为探究遗传和环境因素对饮茶行为的影响提供线索。方法 样本选自2010-2018年在CNTR进行登记的双生子,纳入≥18岁且具有饮茶信息的双生子共25 264对进行分析,描述双生子中饮茶行为的人群、地区分布特征,以及不同卵型双生子饮茶行为一致率和对内饮茶量差异分布情况。结果 研究对象年龄（35.38±12.45）岁,每周饮茶者占比17.0%,饮茶量（3.36±2.44）杯/d。男性、50~59岁、南方、城镇、文化程度高、双生子中先出生的个体中每周饮茶者比例较高（P<0.05）,未婚者中比例较低（P<0.001）。双生子对内分析发现同卵饮茶行为一致率均大于异卵,饮茶遗传度为13.45%（11.38%~15.51%）,除女性亚组外,不同性别、年龄、地区间饮茶一致率差异有统计学意义（均P<0.05）;根据性别、年龄、地区分层后仅男性同卵一致率始终呈大于异卵趋势。同性别双生子对内饮茶量差异在男性中呈现同卵小于异卵的特征（P<0.05）,而女性中差异不明显。结论 本研究双生子人群饮茶行为的分布存在人群和地区差异,饮茶行为主要受环境因素影响,遗传因素影响较弱,且遗传效应大小在不同性别、年龄、地区间不尽相同,性别可修饰这一遗传作用。     

中国成年双生子体质指数的分布特征

目的 描述中国双生子登记系统（CNTR）成年双生子BMI的分布特征,探索BMI在双生子人群中的特殊分布规律,为超重及肥胖高危因素分析和制定防制策略提供线索和基础资料。方法 选自CNTR中2010-2018年完成问卷调查的双生子对,纳入≥ 18岁具有完整双生子对登记信息,且身高、体重等关键变量无缺失或异常者进行分析,共计32 725对成年双生子。描述CNTR项目成年双生子BMI的人群、地区分布特征及双生子对内成员BMI差异的分布现况。结果 研究对象年龄（34.6±12.4）岁,同性别双生子对79.7%。研究对象平均BMI为22.5 kg/m²,超重率为23.7%,肥胖率为4.9%。男性、50~59岁组、北方地区、低文化程度者、在婚者的双生子超重率和肥胖率相对更高（P<0.001）。同卵和异卵间差异无统计学意义,但先出生的双生子超重和肥胖率略高于后出生者（P<0.05）。同性别双生子对内分析发现,对内BMI差异与年龄呈正相关（趋势性检验P<0.001）,异卵差异高于同卵,且卵型间差异随年龄增长发生变化。BMI一致率存在卵型差异（P<0.05）,同卵高于异卵。结论 本研究的双生子人群BMI的分布存在人群和地区差异;BMI为可遗传的性状,且遗传作用可能随年龄而变化。     

2004－2018年中国1岁以下低出生体重儿死亡水平与变化趋势

目的 分析2004－2018年中国<1岁组儿童低出生体重儿死亡水平与变化趋势。方法 利用公开出版的《2004－2018年中国死因监测数据集》,分析我国<1岁组儿童在不同性别、城乡、地区的低出生体重儿死亡率、构成比及变化趋势。分析城乡、东/中/西部地区不同性别<1岁组低出生体重儿死亡率、构成比及变化趋势。采用加权最小二乘法拟合Joinpoint回归模型分析时间变化趋势,计算各时间段内年度变化百分比（APC）、全时段内平均年度变化百分比（AAPC）及其95% CI。结果 2004－2018年<1岁组低出生体重儿死亡率呈下降趋势,年平均下降幅度为-8.0%（95% CI：-10.6%~-5.4%）,不同性别、城乡、地区间的差异逐渐缩小。2004－2018年<1岁组低出生体重儿死亡构成比呈上升趋势,年平均上升幅度为1.6%（95% CI：0.1%~3.2%）。<1岁组低出生体重儿死亡率城市（38.74/10万）高于农村（30.44/10万）,城市<1岁组低出生体重儿死亡率年平均下降速度（-3.4%,95% CI：-7.0%~0.3%）低于农村（-9.3%,95% CI：-12.0%~-6.6%）;<1岁组男童低出生体重儿死亡率（36.25/10万）高于女童（28.22/10万）;西部地区<1岁组儿童低出生体重死亡构成比呈上升趋势,平均每年变化为3.2%（95% CI：1.7%~4.8%）,变化速度高于东部地区的-0.5%（95% CI：-2.3%~1.4%）;不同城乡、地区间<1岁组低出生体重儿死亡率男童均高于女童。结论 2004－2018年<1岁组低出生体重儿死亡率呈下降趋势,构成比均呈上升趋势,建议以男童和中、西部地区儿童作为今后妇幼保健工作的重点人群。     

出生队列效应对体质指数遗传度的影响

目的 探索不同出生队列BMI遗传度的变化情况。方法 基于中国双生子登记系统丽水和青岛两个时点的双生子,按照出生年份分为1958年及以前出生、1959-1961年出生、1962-1970年出生和1971年及以后出生的4个出生队列,在各个时点分别拟合结构方程,计算不同出生队列在不同年龄的遗传度。结果 每个出生队列中,2012年时的体重、BMI高于2001年;出生于1971年及以后的双生子无论体重和BMI均低于其余出生队列。遗传因素能解释BMI的表型变异为54%~76%;出生于1959-1961年的双生子,BMI的遗传度随年龄上升,其余出生队列遗传度较为稳定。结论 BMI受遗传因素影响较大,出生于1959-1961年的双生子,随着年龄增长,遗传因素对BMI的影响增加。     

出生体重与成年期体格指标的双生子研究

目的 研究出生体重与成年期体格指标（BMI、腰围）表型的相关性,分解相关性可能的来源。方法 本研究使用中国双生子登记系统基线调查的年龄在25~79岁间的同性别双生子对（共6 623对）,通过问卷调查收集其出生体重、目前身高、体重及腰围。采用双生子对内对照设计的方法探索出生体重与成年期体格指标的相关性,采用结构方程模型分解相关性的来源。结果 在调整多种混杂因素后,同卵双生子对内分析结果显示出生体重每增加1.0 kg,成年后BMI增加0.33 kg/m²,腰围增加0.95 cm。结构方程模型结果显示出生体重与BMI、腰围均存在双生子个体特有环境因素的相关。结论 该研究支持成年期体格指标与出生体重的相关受双生子间特有因素的影响。     

中国18岁以下双生子出生体重与超重/肥胖的关联分析

目的 分析出生体重与儿童时期超重/肥胖间的关联。方法 使用中国双生子登记系统基线调查的<18岁双生子人群(共8267对),采用双生子对内对照设计方法,探索出生体重与儿童青少年时期BMI及超重/肥胖之间的关联。结果 调整性别和卵型的影响后,出生体重每增加0.5 kg,超重/肥胖的风险:幼儿及学龄前期(≥ 2且<6岁)儿童增加0.87倍,学龄期(≥ 6且<12岁)儿童增加0.69倍,青春期(≥ 12且<18岁)青少年增加0.28倍。结论 双生子出生体重与幼儿及学龄期超重/肥胖存在正向关联,但在指导实施公共卫生干预措施时仍需谨慎。     

陕西省育龄妇女围孕期增补叶酸对新生儿出生体重的影响

目的 探讨陕西省育龄妇女围孕期增补叶酸对新生儿出生体重的影响。方法 采用分层多阶段随机抽样方法,以问卷调查方式收集2010-2013年陕西省怀孕且结局明确的育龄妇女及其子女的相关信息。将新生儿出生体重和母亲围孕期是否增补叶酸分别以因变量和自变量纳入多重线性回归及分位数回归模型,并控制相关混杂因素。结果 多重线性回归结果显示,围孕期增补叶酸者子女的出生体重高于未增补者,平均提高29.56 g（B=29.56,t=4.69,P<0.01）。分位数回归结果显示,当新生儿出生体重处于q=0～0.55、q=0.65、q=0.75～0.80百分位点时,增补过叶酸的母亲所生育子女的出生体重高于未增补者,差异有统计学意义,且体重提高的幅度不一致,随着出生体重百分位点的增高,增补过叶酸的母亲所生育子女的出生体重与未增补者相比提高幅度逐渐减小。结论 围孕期增补叶酸可以提高新生儿出生体重,对体重较轻的新生儿影响更大,体重较重的新生儿影响较小甚至无影响。     

北京城区1996--2010年多胎妊娠变化趋势及妊娠结局

目的描述1996--2010年北京市多胎妊娠变化趋势,比较单胎和多胎妊娠产妇娠并发症发生率的差异。方法以1996--2000、2005和2010年北京妇产医院和北京市海淀区妇幼保健院分娩的活产儿为研究对象,采用病例回顾分析的方法进行分析。采集项目包括产妇年龄、胎数、分娩方式、是否患有妊娠高血压、妊娠糖尿病、妊娠贫血、新生儿性别、出生体重、孕周等。_l{;生体重及率的趋势分析采用线性回归直线拟合来评价。组间率的比较采用f检验。结果研究对象包括63 661名活产新生儿和62 895名产妇(其中单胎产妇62 135名,多胎妊娠且胎儿均为活产产妇751名)。1996--2010年多胎妊娠发生率呈增加趋势,平均每年增加0.02%(P<0.05);多胎妊娠剖宫产率平均每年增加2.25%(P<0.01);15年来多胎和单胎新生儿出生体重总体变化趋势不明显,2000年以前单胎儿出生体重呈增加趋势,平均每年增加23.7 g(P<0.001);低出生体重发生率变化不明显;早产发生率多胎儿平均每年增加1.62%(P<0.05),单胎儿略呈增加趋势,平均每年增加0.16%(P<0.05)。此期间单胎儿平均出生体重为>3 250 g,多胎JL<2 500 g;多胎儿低出生体重率和早产率显著高于单胎儿;多胎妊娠产妇的剖宫产率明显高于单胎产妇。多胎妊娠产妇的妊娠高血压、妊娠贫血的发生率(44%和11.2%)明显高于单胎妊娠产妇(12.8%和23.2%),妊娠糖尿病发生率差异无统计学意义。结论1995--2010年北京市多胎妊娠率明显增加。多胎妊娠产妇较之单胎妊娠产妇更易于发生妊娠高血压、妊娠贫血。     

7~16岁儿童青少年肥胖与DNA甲基化相关性的双生子研究

目的 基于肥胖不一致双生子人群,在全基因组范围内探索与儿童青少年肥胖相关的DNA甲基化位点。方法 2016年在北京市朝阳区、延庆区及房山区招募90对6~17周岁双生子,通过问卷调查和体格检查收集双生子个人信息以及身高、体重、腰围等;通过美国Illumina公司EPIC芯片进行全基因组甲基化检测,采用R 3.3.1软件进行DNA甲基化数据读取、质量控制和统计学分析。利用肥胖不一致同卵双生子对,采用经验贝叶斯配对调整t检验和Levene检验,分别探索与肥胖相关的DNA甲基化差异位点和DNA甲基化变异差异位点。结果 根据研究定义,共纳入23对肥胖不一致同卵双生子对,年龄范围7~16岁。共有817 471个合格CpG位点纳入全基因组相关分析,未发现满足多重校正标准的肥胖相关DNA甲基化阳性位点,P值最小的DNA甲基化差异位点为12号染色体上的位点cg05684382（P=1.26E-06,FDR>0.05）,P值最小的DNA甲基化变异差异位点为16号染色体CMIP基因主体上的位点cg26188191（P=6.44E-06,FDR>0.05）,均为EPIC芯片新增位点。结论 基于本研究人群,研究未发现满足显著性要求的肥胖相关DNA甲基化阳性位点,但分析提示cg05684382、cg26188191可能与肥胖发生相关。     

中国育龄夫妇不孕率系统综述

目的 运用循证分析方法估计中国育龄夫妇不孕率及其在不同地区和人群间的差别.方法 检索1980-2012年万方、维普、CNKI、PubMed数据库关于不孕率调查的文献,通过Meta分析合并不孕率,并通过Meta回归分析发现不孕率变异的来源.结果 纳入文献27篇.中国各地区总合并不孕率为5.7％(95％CI:5.3％-6.1％),新婚人群1年和2年合并不孕率分别为12.5％(95％CI:9.5％-15.4％)和6.6％(95％CI:4.9％-8.4％);非新婚人群的1年和2年合并不孕率分别为6.4％(95％CI:4.2％-8.6％)和3.0％(95％CI:2.6％-3.3％).Meta回归分析发现各地区2年不孕率低于1年不孕率,经济水平低的地区不孕率高,文献的研究方法中历史性队列研究和前瞻性研究的不孕率较高.结论 由于各研究对于不孕率的界定不-致,导致各研究间不具有绝对的可比性.应重视各不孕率调查的可比性问题.     

Birth weight and risk of angina pectoris: analysis in Swedish twins

Objective: Intrauterine nutrition approximated by birth weight has been shown to be inversely associated with risk of coronary heart disease (CHD). By investigating the association within twin pairs discordant for disease, the influence of genetic and early environmental factors is substantially reduced. Methods: We have investigated the association between birth weight and angina pectoris in same-sexed twins with known zygosity included in the population-based Swedish Twin Registry. Self-reports of birth weight and angina pectoris were collected in a telephone interview between 1998 and 2000. The cohort analyses were based on 4594 same-sexed twins, and the within-pair analyses included 55 dizygotic and 37 monozygotic twin pairs discordant for angina pectoris. Odds ratios (OR) and 95% confidence intervals (CI) were calculated by logistic regression. Results: Compared with birth weight between 2.0 and 2.9 kg, low birth weight (<2.0 kg) was associated with increased risk of angina pectoris in the twin cohort, (OR: 1.46; 95% CI: 1.14–1.87), but after adjustment for potential confounders the risk decreased, and did not reach significance. Within twin pairs discordant for angina pectoris, low birth weight was significantly associated with increased risk of angina pectoris within dizygotic twins (adjusted OR: 5.73; 95% CI: 1.59–20.67), but not within monozygotic twins (adjusted OR: 1.20; 95% CI: 0.40–3.58). Conclusions: The results suggest that genetic differences associated with foetal growth and adult risk of CHD may have affected previously reported associations between birth weight and CHD.     

Birth weight and body composition in young women: a prospective twin study

BACKGROUND: The intrauterine environment may be critical for the development of obesity. Alternatively, the same genetic factors may influence both birth weight and adult body composition. OBJECTIVE: We evaluated the association between birth weight and adult body composition in female twins, which allowed us to control for maternal and genetic influences. DESIGN: Of 447 twin pairs randomly selected from the East Flanders Prospective Twin Survey, 238 pairs, aged 18-34 y, participated. Adult body mass, height, and lean body mass were measured, and the body mass index (BMI), waist-to-hip ratio, and sum of skinfold thicknesses were calculated. The twins were considered as individuals and pairs. RESULTS: When the twins were considered as individuals, twins who were heavier at birth were taller (3.3 cm/kg greater birth weight) and slightly heavier (1.13 kg/kg greater birth weight) as adults than were lighter twins. They also had more lean body mass and less subcutaneous and abdominal fat at birth. Pairwise comparison showed that for every level of intrapair birth weight difference (> or = 5%, > or = 10%, and > or = 15%), the twin who was heavier at birth was taller in adult life (0.8, 1.2, and 2.0 cm, respectively). When the intrapair birth weight difference exceeded 15%, the heavier twin was also heavier (3.1 +/- 6.08 kg) as an adult than her much lighter sister. CONCLUSION: Birth weight accounts for some of the differences in adult body composition between twins.     

Perinatal characteristics and risk of polio among Swedish twins

Perng W, Cnattingius S, Iliadou A, Villamor E. Perinatal characteristics and risk of polio among Swedish twins. Paediatric and Perinatal Epidemiology 2012; 26: 218–225. Prenatal exposure to adverse environmental conditions is related to increased adult mortality in regions where infections are highly prevalent, yet there is little evidence of the impact of perinatal conditions on the risk of severe infections throughout life. Using prospectively collected data from 21 604 like‐sexed Swedish twins of known zygosity born in 1926–1958, we examined the risk of polio in relation to perinatal characteristics using cohort and nested co‐twin case–control analyses. Polio incidence was determined through an interview in 1998, and linkage with the Swedish national inpatient and death registries. There were 133 cases of polio. In the cohort analysis, birth length, birthweight and head circumference were positively associated with polio risk. After adjustment for sex, birth year, gestational age at birth and within‐twin pair correlations, twins of shortest length (<44 cm) had a 67% ([95% CI: 6%, 88%]; P = 0.04) lower risk of polio compared with the reference group (47–49 cm). After additional adjustment for birth length, every 100‐g increase in birthweight was related to a 34% increased risk of polio ([95% CI: ?1%, 82%]; P = 0.06), and every 10‐mm increase in head circumference was related to a 17% greater risk of polio ([95% CI: 5%, 31%]; P = 0.004). In co‐twin control analyses among 226 disease‐discordant twins, birth length, birthweight and head circumference were 0.3 cm (P = 0.19), 84 g (P = 0.07) and 3 mm (P = 0.08) higher in cases than controls, respectively. Similar associations were observed among monozygotic (n = 84) and dizygotic (n = 142) twins. These findings suggest that early intrauterine growth restriction may be inversely related to the incidence of polio.     

双胎输血综合征与发育不同一性双胎妊娠的妊娠结局对比分析

目的分析比较双胎输血综合征与发育不同一性双胎妊娠的妊娠结局。方法收集1999年1月至2009年8月中山三院分娩的23例双胎输血综合征(A组)和43例发育不同一性双胎妊娠(B组)的临床资料,对比分析2组在一般情况、发生孕周、妊娠并发症、合并症、分娩情况和围产儿预后方面的差异。结果 A组平均发生孕周为25+4周,较B组平均发生孕周31+3周要早,A组分娩孕周平均为29+5周,B组分娩孕周平均为35+3周,2组差异有统计学意义(P<0.05)。A组晚期流产、羊水过多、双胎之一胎死宫内和胎盘早剥的发生率分别为26.1%、47.8%、21.7%和13%,B组为13.9%、20.9%、9.3%和2.3%,2组差异有统计学意义(P<0.05)。A组围产儿死亡率45.7%,新生儿窒息率69.6%;B组围产儿死亡率为30.2%,新生儿窒息率40.7%,2组差异有统计学意义(P<0.05)。A组新生儿平均出生体质量(1732±673)g,B组平均出生体质量为(2321±568)g,2组差异有统计学意义(P<0.05)。结论双胎输血综合征和发育不同一性双胎妊娠都是双胎妊娠特有的并发症,临床表现均以胎儿发育不一致为特征,然而2者在发病机制与妊娠结局上仍有不同,临床上应予重视并鉴别,及时处理,改善围产儿预后。     

Teen Maternal Age and Very Preterm Birth of Twins

Background: As teen singleton pregnancy is associated with higher risks of adverse birth outcome, and twin pregnancy, regardless of maternal age, may result in poor outcome, teens pregnant with twins may represent a particularly vulnerable group. However, little has been documented regarding teen twin pregnancy outcome. Objective: To characterize the risk of very preterm birth among teens having twins. Design: Cross-sectional analysis of the US 1995–2000 Matched Multiple Birth Data Set. Methods: We calculated the risk of very preterm birth (<33 weeks' gestation) for teen and young adult mothers of twins (≤16 years, 17–18 years, 19–20 years), compared to 21–24 year olds, stratified by race/ethnicity. Adjusted odds ratios were estimated controlling for marital status and entry into prenatal care. Results: Odds of very preterm birth decreased significantly with increasing age. Odds ratios ranged from 2.07 (1.73,2.48) to 1.20 (1.11,1.29) according to maternal age for White teen mothers, from 1.76 (1.48,2.09) to 1.13 (1.03,1.24) for Black teen mothers, and from 2.19 (1.77,2.72) to 1.15 (1.02,1.31) for Hispanic teen mothers. Odds of very preterm birth among teen mothers of twins were about the same as those for teen mothers of singletons. Conclusions: Teens having twins have higher odds of very preterm birth than young adult mothers. However, the association between age and preterm birth was similar among teen mothers having twins as for those having singletons.