Effect of environmental and genetic factors on education-associated disparities in weight and weight gain: a study of Finnish adult twins

BACKGROUND: Disparities in body mass index (BMI) between persons with different educational levels in Western countries are well documented, but the background of these education-associated disparities remains poorly understood. OBJECTIVE: The objective was to examine the influence of environmental and genetic factors on education-associated disparities in self-reported BMI and weight change. DESIGN: Longitudinal postal surveys were performed in 1975, 1981, and 1990. The data were analyzed by using multivariate genetic models for twin data. The data derived from the Finnish Twin Cohort included 2482 monozygotic and 5113 dizygotic same-sex male and female twin pairs born between 1915 and 1957. RESULTS: Education-associated differences in BMI and in weight change were clear in 1975 and 1981, respectively, whereas no differences were seen in weight change between 1981 and 1990 when age and baseline BMI were adjusted for. The trait correlation between baseline BMI and educational attainment (-0.15 in men and women) was mainly due to correlations between additive genetic factors that contributed to BMI and education in men (-0.20; 95% CI: -0.25, -0.14) and women (-0.32; 95% CI: -0.40, -0.25) when adjusted for age. Among women, a weaker positive correlation was found for the unshared environmental effects contributing to the 2 traits (0.06; 95% CI: 0.02, 0.12). The same factors that affected the association between education and BMI in 1975 largely explained the association between education and weight change in 1981. CONCLUSION: The results suggest the possibility that common genetic factors affect educational attainment and body weight, which contribute to education-associated disparities in BMI in adulthood.     

孕中期血糖水平与新生儿出生体重的队列研究

目的 探讨孕中期孕妇75 g口服糖耐量试验(OGTT)的3项血糖值与出生体重的关系。方法 参与前瞻性队列研究的3 081名孕妇于孕≤14周时收集基础人口统计学信息,在孕24～28周行75 g OGTT,利用多项logistic回归法分析新生儿出生体重的影响因素及孕中期FPG和OGTT-1 h、OGTT-2 h值四分位分组的大于胎龄儿(LGA)发生风险,以多元线性回归法分析血糖值与新生儿出生体重的关系。结果 孕前超重(24.0 kg/m²≤BMI <28.0 kg/m²)(OR=1.4,95%CI:1.0～2.0,P=0.029)、妊娠期糖尿病(OR=2.4,95%CI:1.8～3.2,P <0.001)是LGA发生的危险因素;孕前消瘦(BMI <18.5 kg/m²)(OR=1.6,95%CI:1.2～2.2,P=0.003)、子痫前期(OR=4.0,95%CI:1.9～8.4,P <0.001)可增加小于胎龄儿出生的风险。多元线性回归分析调整孕前BMI、产次、高血压情况、新生儿性别后,FPG、OGTT-1 h和OGTT-2 h均与新生儿出生体重呈正相关关系(β 值分别为91.99、33.60、32.00,P值均 <0.001)。随着孕妇3项血糖水平四分位升高各组出生体重呈增大趋势,且LGA发生风险逐渐增大。结论 孕中期血糖水平与子代出生体重呈正相关。随着血糖水平升高,新生儿出生体重增大,LGA发生风险升高,但小于胎龄儿与血糖无关联。FPG值对发生LGA有很好的预测作用。     

Estimated birth weight and adult cardiovascular risk factors in a developing southern Chinese population: a cross sectional study

Background  

Birth weight is negatively associated with cardiovascular diseases and diabetes, but the associations are less well-established in developing populations where birth weight is often unavailable. We studied the association of birth weight and cardiovascular risk, using birth rank as an instrumental variable, in Southern China.     

4144例单胎活产儿出生体重相关影响因素分析

目的:探讨新生儿出生体重的相关影响因素。方法:选取唐山市人民医院2001年1月1日~2004年12月31日出生的4 144例单胎活产新生儿,对其出生体重的相关影响因素进行分析。结果:不同性别的新生儿平均出生体重比较有极显著性差异(P<0.01),不同文化程度的产妇其新生儿平均出生体重比较也有极显著性差异(P<0.01),不同孕次的产妇新生儿出生体重比较有显著性差异(P<0.05),不同产次的新生儿平均出生体重比较无显著性差异(P>0.05),在本研究中未发现产妇年龄以及产前血红蛋白含量和新生儿出生体重有相关关系。结论:本次调查发现,产妇的文化程度、孕次、新生儿性别是新生儿出生体重的影响因素。     

Maternal and cord blood manganese (Mn) levels and birth weight: The MIREC birth cohort study

Epidemiological studies have hypothesized that both insufficient and excess blood manganese (Mn) levels during pregnancy are associated with reduced fetal growth. This literature is characterized by inconsistent results and a limited focus on women with exposures representative of the general North American population. We examined the relationship between maternal and cord blood Mn levels and fetal growth among women enrolled in the Maternal-Infant Research on Environmental Chemicals Study (MIREC). Mothers with singleton, term infants and complete maternal first and third trimester blood Mn data were eligible for inclusion in the present study (n?=?1519). Mean birth weight and odds ratios of small for gestational age (SGA) births according to maternal and cord blood Mn levels (low (<10), referent (10–<90), high (≥90) percentiles) were estimated. We also evaluated the association between the ratio of cord and maternal blood Mn and birth weight. Women with low (<0.82?μg/dL) maternal blood third trimester Mn levels had infants that weighed an average of 64.7?g (95% CI: ?142.3,12.8) less than infants born to women in the referent exposure group. This association was strengthened and became statistically significant when adjusted for toxic metals (lead, mercury, arsenic, and cadmium) [?83.3?g (95% CI: ?162.4, ?4.1)]. No statistically significant associations were observed in models of maternal first trimester or cord blood Mn. A one unit increase in the cord/maternal blood Mn ratio was associated with a 29.4?g (95% CI: ?50.2, ?8.7), when adjusted for maternal and neonatal characteristics. Our findings motivate additional research regarding the relation between Mn exposure and fetal growth. Further inquiry is necessary to determine whether an exposure threshold exists, how growth related effects of maternal and fetal Mn may differ, and how concurrent exposure to other toxic metals may impact the association between Mn and growth.     

Twin study of genetic and environmental effects on lipid levels

A study of 106 pairs of monozygotic (MZ) and 94 pairs of dizygotic (DZ) twins tested the hypothesis that part of the previously described genetic influence on blood lipid levels can be ascribed to closer similarities among MZ than among DZ twin pairs in environmental factors that affect lipid levels. Participants were adult twin volunteers (age 17-66; 64 male and 136 female pairs) who were selected from the NH & MRC Twin Registry or were respondents to advertisements. They completed a 4-day weighed food diary from which mean nutrient intake was derived. Information on lifestyle and demographic variables was obtained by questionnaire and a nonfasting blood sample was taken for measures of total, low-density lipoprotein (LDL) cholesterol, and high-density lipoprotein (HDL) cholesterol and the HDL2 and HDL3 subfractions. Height and weight were measured, and body mass index (BMI) was calculated (kg/m2). Estimates of the heritability of sex-adjusted lipid levels were 0.72 for total cholesterol, 0.79 for HDL cholesterol, 0.69 for HDL2, 0.20 for HDL3, 1.06 for LDL cholesterol, and 0.44 for sex-adjusted BMI. In all cases except for HDL3, genetic variance was statistically significant. After adjusting for the effects of environmental variables in three different ways, the estimates of heritability were somewhat lower for total cholesterol, HDL2, and BMI, and those for HDL cholesterol (borderline) and LDL cholesterol (definitely) remained statistically significant but were decreased. A genetic influence on HDL3 was not found. Adjusted heritability estimates obtained from one method of analysis were 0.35 for total cholesterol, 0.49 for HDL, 0.04 for HDL2, -0.34 for HDL3, 0.66 for LDL, and 0.32 for BMI. These results suggest that the assumptions made in the classical twin study approach are not appropriate when examining genetic effects on lipid levels or BMI, or indeed on any biological variable that may be affected by environmental factors that tend to be more similar in MZ twins than in DZ twins. In these circumstances, more complex models may be needed to differentiate between genetic and environmental influences.     

低出生体重儿影响因素病例对照研究

目的 分析低出生体重儿发生的相关因素,探讨降低低出生体重儿的干预措施.方法 应用病例对照研究方法,对2004年9月~2006年6月在福建省妇幼保健院分娩的896名孕妇进行调查,进行单因素及多因素Lo-gistic回归分析.结果 文化程度低、社会经济状况差、无固定职业、丈夫吸烟、饮酒及未接受健康教育的孕妇低出生体重儿发生率较高.多因素Logistic回归分析显示,居住面积小、孕期保健次数少、丈夫经常饮酒、未接受健康教育、丈夫情绪焦虑、首次孕期保健周数长等为低出生体重发生的危险因素,而丈夫经常在家看电视为保护因素.结论 加强健康教育、改善经济状况及良好的生活行为方式可有效降低低出生体重儿的发生.     

Cord blood lipid profile and associated factors: baseline data of a birth cohort study

The cord blood lipid profile may be associated with lifelong changes in the metabolic functions of the individual. The aim of the present study was for the first time in Iran to assess the cord blood lipid profile of neonates, as well as some of its environmental influencing factors. The subjects were 442 (218 boys and 224 girls) normal vaginal delivery newborns. Overall, 14.4% of neonates were preterm and the rest were full-term. In total, 9.2% (n = 35) of the full-term newborns were small-for-gestational-age (SGA), of which 16 had a ponderal index (PI) below the 10th percentile (SGA I) and 19 had a PI above the 10th percentile (SGA II), 5.5% (n = 21) were large-for-gestational-age (LGA), and the remainder were appropriate-for-gestational-age (AGA).Before becoming pregnant, 6.9% of mothers were underweight, 49.3% had normal body mass index (BMI), 39.4% were overweight and 4.4% were obese. Total and high-density lipoprotein cholesterol (HDL-C) in girls were significantly higher than in boys (80.3 +/- 33.3 and 31.1 +/- 9.9 vs. 73.3 +/- 23.1 and 28.8 +/- 8.7 mg/dL, respectively, P < 0.05). The mean apolipoprotein A (apoA) of neonates with underweight mothers was significantly lower, and the mean apoB level of those with overweight mothers was significantly higher than other neonates. The mean low-density lipoprotein cholesterol (LDL-C), HDL-C and apoA of the LGA newborns were significantly lower, and their apoB was significantly higher compared with AGA and SGA neonates. The SGA I neonates had significantly lower total cholesterol, LDL-C, HDL-C and apoA, as well as higher triglycerides, lipoprotein a and apoB than the SGA II group. The mean cord blood triglycerides of full-term neonates was significantly higher than preterm neonates (69.4 +/- 11.9 vs. 61.4 +/- 12.7 mg/dL, respectively, P = 0.04). A preconception maternal BMI of > or =25 kg/m(2) correlated significantly with the cord triglycerides (OR = 1.3, [95% CI 1.07, 1.5]) and with apoB (OR = 1.4, [95% CI 1.1, 1.5]). The BMI <18 of mothers before pregnancy correlated with low HDL-C (OR = 1.3, [95% CI 1.04, 1.7]). Birthweight correlated with high cord triglyceride level (SGA: OR = 1.4, [95% CI 1.1, 1.7]; LGA: OR = 1.6, [95% CI 1.3, 1.7] compared with AGA). These associations remained significant even after adjusting for the preconception BMI of mothers. Our findings reflect the possible interaction of environmental factors and fetal growth and the in utero lipid metabolism. Long-term longitudinal studies in different ethnicities would help to elucidate the relationship.     

足月低出生体重儿发生影响因素的病例对照研究

【目的】　探讨足月低出生体重儿发生的影响因素,为临床诊治提供依据。　【方法】　对111 例足月低出生体重儿和750名正常对照组婴儿进行相关因素调查,并采用二项式Logistic回归对影响足月低出生体重儿发生的有关因素进行分析。　【结果】　父母亲身高、职业、文化程度、吸烟、母亲孕前体重、初潮年龄、多胎、产前检查次数、妊娠高血压综合征、年家庭经济收入等因素与足月低出生体重儿发生有关(OR=0.894~9.275,P均<0.05)。　【结论】　足月低出生体重儿的发生与多种因素有关。     

新生儿早产、低出生体重及小于胎龄的危险因素

目的 研究早孕期相关暴露因素与新生儿早产、低体重及小于胎龄的关系。方法 选取“中国孕产妇队列研究·协和”项目于2017年7月25日至2018年7月24日入组并于2018年12月31日前分娩且符合纳入标准的3 172例孕妇为研究对象,使用二分类logistic回归分析对早孕期相关暴露因素与新生儿不良分娩结局的关系进行统计分析。结果 新生儿早产、低体重及小于胎龄的发生率分别为4.76%、3.53%、5.74%。在早产方面,北方孕妇和孕期增重是早产的保护因素,而胎膜早破、妊娠期高血压、1～3年内有口腔检查或治疗、家庭人口为3～4人是早产的危险因素。在低出生体重方面,孕期增重和食用奶及奶制品是低出生体重儿的保护因素,而胎膜早破、妊娠期高血压、工作久坐时间>6 h、1～3年内有口腔检查或治疗、被动吸烟等是低出生体重儿的危险因素。在小于胎龄方面,女婴、被动吸烟、食用花生油及口味偏淡是小于胎龄儿的危险因素,而补充叶酸是小于胎龄儿的保护因素。结论 新生儿早产、低体重及小于胎龄的影响因素是多因素的,应针对相关危险因素采取有针对的预防和干预措施以降低新生儿不良出生结局的发生风险。     

双绒毛膜双胎胎盘血管结构与胎儿体重的关系

目的 探讨双绒毛膜双胎胎盘血管结构与新生儿体重的关系.方法 选择广州医学院第一附属医院2008年分娩的、成功获得血管铸型标本的3例胎盘,对胎盘血管网体积和面积与相应6例新生儿出生体重进行统计分析.结果 新生儿出生体重与胎盘血管网体积的相关系数r=0.95,两者高度相关.新生儿出生体重与胎盘血管网面积的相关系数r=0.17.结论 胎儿宫内生长与胎盘的体积及其脐带因素关系密切,妊娠中期及其以前能利用超声检查及早作出判断,使得在妊娠中晚期能采取适当措施严密监护,对减少围生儿发病和死亡率有积极意义,尤其是多胎妊娠.     

中国低出生体重儿危险因素的病例对照研究

目的 探讨我国不同特征低出生体重儿发生的有关危险因素。方法 1998年7－10月,对我国11个省44个县市的999例低出生体重儿进行1：！病例对照研究。结果 我国低体重儿发生的危险因素主要为多胎、孕周不足、孕期异常、孕期营养差、母亲疾病史及母亲程度低等,其OR值分别为106．9、18．79、3．42、1．93、2．61和1．43。各危险因素在沿海、内地及边远地区的分布差异有显著性。农村低体重儿的原因主要为宫内发育迟缓（71．6％）,城市低体得儿的原因还包括多胎和早产。早产及宫内发育不全的低出生体重儿之间的危险因素存在差异。结论 有针对性地开展防治工作是降低我国低体重儿出生率的有效措施。     

The influence of maternal age on very preterm birth of twins: differential effects by parity

For singleton births, parity can modify the effect of maternal age on birth outcomes such as low birthweight and preterm birth; however, it is unknown whether this relationship exists for twin births. As the rate of twin births increases among older women, it is important to understand how parity may influence the relationship between maternal age and adverse birth outcomes. The NCHS Matched Multiple Birth Data Set, which contains all twin births in the USA from 1995 to 1998, was analysed. Parity was grouped into two levels (primiparous--no prior live births, and multiparous--at least one prior live birth), and maternal age was divided into the following groups: 20-24, 25-29, 30-34, 35-39, and 40 years or more. Very preterm birth was defined as births occurring before 33 weeks. Logistic regression was used to obtain odds ratios (OR) to estimate the risk of very preterm birth, and to determine the relationships between parity, maternal age, and very preterm birth. Among primiparae, women 40 years and older had a reduced risk of very preterm birth compared with women of 25-29 years (OR 0.74 [95% CI=0.66, 0.84]). Among multiparae, women 40 years and older had the same risk of very preterm birth compared with women of 25-29 years (OR 1.00 [95% CI=0.90, 1.12]). However, stratification by education revealed that the age gradient was limited to women with >12 years education among primiparae. The effect of maternal age on very preterm birth of twins differs according to parity. To some extent, that effect is further modified by education. Therefore, future analyses of maternal age and twin birth outcomes should account for measures of obstetric history and other factors, which may influence these results.     

Poor agreement between self-reported birth weight and birth weight from original records in adult women

Data from an ongoing prospective population study of women in G?teborg, Sweden, were used to assess agreement between self-reported birth weight and birth weight obtained from original delivery records of women aged 44-60 years. Of the eligible population with traced delivery records (n = 693), only 28% (n = 192) could report their own birth weight. Spearman correlation between self-reported birth weight and birth weight from original records was r = 0.76. However, a difference plot, with limits of agreement at -1,028 to 1,038 g (95% confidence limits: lower limit, -1,157 to -901 g, upper limit, 910 to 1,166 g) revealed poor agreement between methods. Of the self-reported birth weights, 53% were in error by 250 g or more, and 31% were positively or negatively discordant by 500 g or more. Application in an analysis of cardiovascular risk factors in adulthood found conflicting results between self-reported and recorded birth weights. Low reporting rate, poor reporting accuracy, and misleading findings in application led to the conclusion that self-reported birth weights from middle-aged women would not be a satisfactory replacement for birth weights from original records.     

Genetic effects on weight change and food intake in Swedish adult twins

BACKGROUND: Obesity is influenced by genetic and environmental factors. Additionally, synergistic effects of genes and environments may be important in the development of obesity. OBJECTIVE: The aim of this study was to test for genetic effects on food consumption frequency, food preferences, and their interaction with subsequent weight gain. DESIGN: Complete data on the frequencies of consumption of 11 foods typical of the Swedish diet were available for 98 monozygotic and 176 dizygotic twin pairs aged 25-59 y who are part of the Swedish Twin Registry. The data were collected in 1973 as part of a questionnaire study. Body mass index was measured in 1973 and again in 1984. RESULTS: There was some evidence that genetic effects influenced the frequency of intake of some foods. Similarity among monozygotic twins exceeded that among dizygotic twins for intake of flour and grain products and fruit in men and women, intake of milk in men, and intake of vegetables and rice in women, suggesting that genes influence preferences for these foods. Analyses conducted for twins reared together and apart also suggested greater monozygotic than dizygotic correlations, but cross-twin, cross-trait correlations were all insignificant, suggesting that the genes that affect consumption frequencies are not responsible for mediating the relation between the frequency of intake and weight change. CONCLUSIONS: Genetic effects and the frequency of intake are independently related to change in body mass index. However, there was no suggestion of differential genetic effects on weight gain that were dependent on the consumption frequency of the foods studied.     

The effect of nutritional factors on sex hormone levels in male twins

Dietary intake has been hypothesized as being associated with several hormonally related cancers including prostate, breast, ovarian, and endometrial cancer. Because diet may affect hormones directly, it is logical to examine the effects of dietary factors on hormone production and levels. Therefore, a set of 72 male MZ and 83 male DZ twin pairs was ascertained from the Utah birth certificates. A quantitative food frequency questionnaire was administered and blood samples were drawn for hormonal assays. Heritability estimates for hormonal levels were calculated indicating a range from no heritability for sex hormone binding globulin (SHBG), estrone, and testosterone glucuronide to 70% for androstanediol glucuronide and luteinizing hormone. To examine nutritional factors, the difference in hormone and SHBG levels between each MZ twin and his co-twin were correlated with the difference in nutrient intake. Weight and obesity were significantly correlated with plasma testosterone and follicle stimulating hormone. Fat intake showed a significant association with testosterone. Androstanediol glucuronide, a steroid that reflects tissue formation of dihydrotestosterone, was inversely correlated with caloric intake, theobromine and caffeine. Testosterone glucuronide exhibited significant correlations with calories and vitamin A. This study suggests that dietary intake affects plasma sex-steroid levels in men.     

The relationship between body mass index and uric acid: a study on Japanese adult twins

Objectives

The present study aimed to investigate the association between body mass index (BMI) and uric acid (UA) using the twin study methodology to adjust for genetic factors.

Methods

The association between BMI and UA was investigated in a cross-sectional study using data from both monozygotic and dizygotic twins registered at the Osaka University Center for Twin Research and the Osaka University Graduate School of Medicine. From January 2011 to March 2014, 422 individuals participated in the health examination. We measured height, weight, age, BMI, lifestyle habits (Breslow’s Health Practice Index), serum UA, and serum creatinine. To investigate the association between UA and BMI with adjustment for the clustering of a twin within a pair, individual-level analyses were performed using generalized linear mixed models (GLMMs). To investigate an association with adjustment for genetic and family environmental factors, twin-pair difference values analyses were performed.

Results

In all analysis, BMI was associated with UA in men and women. Using the GLMMs, standardized regression coefficients were 0.194 (95 % confidence interval: 0.016–0.373) in men and 0.186 (95 % confidence interval: 0.071–0.302) in women. Considering twin-pair difference value analyses, standardized regression coefficients were 0.333 (95 % confidence interval: 0.072–0.594) in men and 0.314 (95 % confidence interval: 0.151–0.477) in women.

Conclusions

The present study shows that BMI was significantly associated with UA, after adjusting for both genetic and familial environment factors in both men and women.