The contrasting effects of parental birthweight and gestational age on the birthweight of offspring

Investigations on intergenerational effects on birthweight have been carried out using the data of the 1958 British National Birthday Trust Fund cohort and its follow-up to 23 years, the National Child Development Study (NCDS-4), which included information on all births to cohort members by that age. This report is directed particularly at ascertaining the independent effect of parental gestational age on babies' birthweight. The two main findings are a direct association between parental and offspring birthweight (significant for both mothers and fathers after allowing for confounding factors), but an inverse association with parental gestational age (significant only for the mothers). It is postulated that at least part of this effect is mediated through the association between maternal fetal growth rate and their babies' birthweight; the faster the rate the shorter the gestational age for a given birthweight. It was not possible to ascertain what part genetic factors played in this relationship. Larger and more informative intergenerational studies are needed to further knowledge on this question.     

Mortality of twins and singletons by gestational age: a varying-coefficient approach

This study used data from the Swedish Medical Birth Registry between 1982 and 1995 to address the question of whether there is higher mortality in twins in relation to singletons of the same gestational age and to examine the optimal gestational age range for twins. A "varying-coefficient approach" was adopted to estimate the gestational age-specific relative and absolute risks of mortality in twins and singletons, adjusting for size at birth and risk factors of short gestational duration. The models showed that twins born between 29 and 37 weeks of gestation had lower mortality than did singletons of the same gestational age. Twins born at older gestational age had higher mortality than did their singleton counterparts, because longer gestational duration was more advantageous to singletons than to twins. Without adjustment for size at birth, there was an upturn of mortality in twins born after 38 weeks. It is postulated that twins have better health than singletons initially, but they could not enjoy the benefit of a longer gestational duration as much as singletons could. The optimal gestational age for twins appeared to be 37-39 weeks according to neonatal and infant mortality.     

A nationwide investigation on gestational age specific birthweight and mortality among Japanese twins

Gestational age specific birthweight has been used as an important indicator to identify the health status of neonates and to provide appropriate neonatal care services to those at high risk. To identify the gestational age specific birthweight of twins born in secondary and tertiary hospitals in Japan and to explore factors affecting mortality, we used a nationwide obstetric database in Japan. Liveborn twins from 2001 to 2005 in the database, which was established with the national Perinatal Health Care Project, were enrolled (n=22,240). Obstetric data from the medical records were collected and analysed. Approximately 60% of liveborn twins were delivered between weeks 33 and 38, most frequently at 36 and 37 weeks. The mean birthweight of liveborn twins was 2084 g and the mean gestational age was 34.9 weeks. Intrauterine growth differed by parity, mode of delivery, birth order, chorionicity and sex. Using logistic regression, lower gestational age, small for gestational age, monochorionic twins and vaginal delivery tended to have higher risks of mortality.     

Sex-specific associations of maternal birthweight with offspring birthweight in the Omega study

PurposeWe investigated nonlinear and offspring sex–specific associations of maternal birthweight (BW) with offspring BW among participants of the Omega study, a pregnancy cohort.MethodsMaternal BW was modeled as a continuous variable, linear spline and binary variable indicating low birthweight (LBW; <2500 vs. ≥2500 grams). Offspring BW was modeled as a continuous and binary variable in regression models. Nonlinearity was assessed using likelihood ratio tests (LRTs) in marginal linear spline models.ResultsFor every 100-gram increase of maternal BW, offspring BW increased by 22.29 (95% CI: 17.57, 27.02) or 23.41 (95% CI: 6.87, 39.96) grams among mothers with normal BW or born macrosomic, respectively, but not among LBW mothers (β = −8.61 grams; 95% CI: −22.88, 5.65; LRT P-value = .0005). For every 100-gram increase in maternal BW, BW of male offspring increased 23.47 (95% CI: 16.75, 30.19) or 25.21 (95% CI: 4.35, 46.07) grams among mothers with normal BW or born macrosomic, respectively, whereas it decreased 31.39 grams (95% CI: −51.63, −11.15) among LBW mothers (LRT P-value < .0001). Corresponding increases in BW of female offspring (16–22 grams) did not differ among mothers with LBW, normal BW or macrosomia (LRT P-value = .9163).ConclusionsMaternal and offspring BW associations are evident among normal BW and macrosomic mothers. These associations differ by offspring sex.     

Decreasing gestational age and birthweight in spastic diplegia

Over a 4-year period a significant fall occurred in the mean birthweight and mean gestational age of prematurely born children who subsequently developed spastic diplegia. This coincided with a considerable improvement in perinatal mortality in the unit in which they were delivered. However, although the number of premature deliveries remained stable, the disorder did not become less common. No specific aetiological factors were identified, but the 24 affected children frequently had a history of adverse prenatal or perinatal factors. We conclude that high standards of obstetric and neonatal care prevent the subsequent development of spastic diplegia in low birthweight infants. However, these factors have also improved the survival of very low birthweight infants who have a much higher risk for the disorder and this has prevented a significant reduction in its frequency.     

运用倾向值匹配法分析孕妇早期呼吸道感染与新生儿出生孕周的关联

目的 探讨孕妇呼吸道感染与活产单胎新生儿出生孕周之间的关联。方法 采用分层随机整群抽样方法,抽取陕西省30个区（县）。面对面问卷调查2010－2013年符合纳入指标的育龄妇女及其生育子女。应用倾向值匹配法,对孕早期呼吸道感染组和无呼吸道感染组进行1∶1匹配。以母亲孕早期呼吸道感染和子女出生孕周分别作为自变量和因变量,通过逐步校正混杂因素共建立3个线性回归模型,其中模型1仅分析匹配前呼吸道感染变量,模型2在模型1的基础上进一步校正母亲及新生儿个体差异因素,模型3仅分析匹配后呼吸道感染变量。结果 共纳入28 848人,孕早期呼吸道感染3 676人（12.74%）。匹配后感染组和非感染组分别为2 762人。模型1显示母亲孕早期出现呼吸道感染,新生儿出生孕周减少0.111周（P<0.001）,模型2减少0.058周（P=0.025）,模型3减少0.076周（P=0.036）。结论 孕妇出现呼吸道感染与子代出生孕周减少有关。     

The relationship between maternal skinfold thickness, smoking and birthweight in black and white women

Summary. A prospective study was conducted in a sample of 1491 multiparous women to ascertain whether the relationship between maternal tricep skinfold thickness and infant birthweight is modified by smoking status and whether the relationship is different in white and black infants. Maternal tricep skinfold thickness measured at midpregnancy was a significant predictor of infant birthweight in both white and black infants after adjusting for gestational age at birth, maternal height, maternal age, parity, alcohol consumption and sex of the infant. However, maternal tricep skinfold thickness was a better predictor of birthweight in smokers compared with nonsmokers. Both white and black women with tricep skinfold thickness below the sample mean had lower infant birthweight than women with tricep skinfold at or above the mean, after adjusting for gestational age at birth, but the difference was greater in smokers (198 g for white and 221 g for black infants) than in nonsmokers (124 g for white and 120 g for black infants). These results suggest that maternal subcutaneous fat measured by tricep skinfold thickness has a greater effect on infant birthweight in smokers compared with nonsmokers, with similar effects in white and black infants.     

Agreement between maternal interview- and medical record-based gestational age.

Agreement between maternal interview- and medical record-based gestational age was assessed by using data from a case-control study of childhood strabismus. The sample consisted of 383 cases of strabismus and their age-matched controls, diagnosed between 1985 and 1986 in Baltimore, Maryland, who were under age 7 years when diagnosed. Medical record-based gestational age was derived, in order of priority, from early ultrasound examination, time from the last menstrual period, pediatric examination, and obstetric examination. The intraclass correlation coefficient, kappa, and mean difference were used to compare agreement between maternal interview- and medical record-based gestational age by maternal and pregnancy characteristics and characteristics related to study design. Overall, 86 percent of mothers were within 2 weeks of the gestational age reported in the medical record. The intraclass correlation coefficient comparing maternal and medical record-based gestational age was 0.83 (95% confidence interval 0.80-0.86). Agreement was positively associated with shorter length of recall, low birth order, and having a neonatal illness related to prematurity. Agreement was poor among mothers of healthy preterm infants. There was a weak positive association between recall and some sociodemographic covariates. There was greater misclassification of prematurity in the controls than in the cases. The results suggest that, in general, women recall gestational age well, which supports the use of gestational age derived from maternal interviews.     

妊娠期糖尿病对后代的影响

妊娠期糖尿病是一种常见疾病,对母儿健康均会产生不良影响,该文着重探讨妊娠期糖尿病对后代的影响.妊娠期糖尿病的胎儿易发生宫内乏氧、窘迫,其发生先天畸形的机率较高;妊娠期糖尿病的新生儿发生心血管异常的死亡率较高,而且出现残疾、神经系统疾病的比率增高;用妊娠期糖尿病母亲的乳汁行母乳喂养,可增加妊娠期糖尿病后代肥胖和糖耐量异常的风险,对后代体格和代谢的影响较大.同时,血糖控制不佳的妊娠期糖尿病后代,精细运动功能较差,易出现多动和注意力不集中.所以对妊娠期糖尿病进行筛查和血糖控制,对孕母和儿童的健康具有重要意义.     

新生儿先天性甲状腺功能低下症与出生体重及胎龄的相关性分析

目的探讨新生儿先天性甲状腺功能低下症与出生体重及胎龄的关系。方法用时间分辨荧光免疫分析法测定2010年1月~2015年7月佛山市(顺德区除外)各产科医院新生儿干血片促甲状腺激素(TSH)值,凡TSH>10.0 m IU/L者予以召回,进行甲状腺功能检查。分别按照出生体重和胎龄进行分组,并对出生体重、胎龄与TSH初筛阳性率及发病率进行相关性分析。结果共筛查标本466 078例,统计有效信息456 094例。确诊先天性甲状腺功能低下症236例,总患病率为1/1 975。其中,低出生体重儿发病率为1/744,正常出生体重儿发病率为1/2 218,巨大儿发病率为1/1 535(χ2=153.45,P=0.004)。早产儿发病率为1/975,足月儿患病率为1/1903,过期产儿患病率为1/5666(χ2=169.63,P=0.003)。不同出生体重和胎龄的患病率差异有统计学意义(P<0.05)。结论新生儿先天性甲状腺功能低下症的发病与新生儿出生时的体重、胎龄等因素有关,早产、低出生体重的新生儿甲状腺功能低下症的患病率最高。因此,加强孕期保健和管理、防止早产和减少低出生体重的发生是降低新生儿先天性甲状腺功能低下症患病率的关键。     

Modulation off birthweight through gestational age and fetal growth

Summary Several factors are known to affect birthweight and their effects are variously mediated through gestational duration or through fetal growth conditional on this gestation, in order to quantify independent associations of birthweight conditional and unconditional on gestational age, all 2538 mothers of singleton babies delivered during 1993 in two Maternity Hospitals in Athens were interviewed and their obstetric records abstracted. Birthweight was modelled as outcome variable through multiple regression including 32 potentially predictive factors. The regression model was fitted with and without gestational age as an additional independent variable in order to apportion birthweight associations into those independent of, or mediated through, gestational length. The factors studied were found to be classifiable into the following categories: factors associated with birthweight mostly through increases in gestational duration, either positively (age at menarche, long menstrual cycles, parity 4 or higher), or negatively (single motherhood, maternal age, tobacco smoking); those associated with birthweight mostly through increase of birthweight conditional on gestational duration, either positively (male gender, short menstrual cycles, maternal pre-pregnancy weight, anaemia, oedema) or inversely (employment during pregnancy, stillbirth, primiparity, pregnancy induced hypertension, coffee drinking); and those associated with birthweight through apparently dual effects, either positively (maternal education) or inversely (perceived stress, bleeding during pregnancy). The other studied factors were not demonstrably related to birthweight in this data set. Identification and quantification of these relations is useful for understanding underlying physiological and pathophysiological processes and for increasing specificity in exploring the association of birthweight with adult onset diseases, like coronary heart disease or cancer.     

Association between maternal work activity on birth weight and gestational age

ObjectiveTo evaluate the effect of maternal employment on birth weight and gestational age.MethodsIn this project, 1 272 pregnant women were recruited from whom referred to Tehran hospitals during 1 year via randomized sampling. Data were gathered through history taking and medical records. In this study, 564 employed women were classified as exposure group and 708 housekeepers were as the control group. Chi square test, t-test, One-way ANOVA and logistic regression were used to analyze data.ResultsIn this study, mean mother age was 25.01 years and mean birth weight was (2 884±684) g. The mean birth weight in housekeepers was significantly higher (2 991±457 g) than employees (2 726±476 g) (P=0.002). The infants' mean birth weights in farmer were the lowest and in office workers (2 831±526 g) was the highest (P<0.01). Gestational age less than 37 weeks was more common among employees. The mean birth weight decreased when the working hours increased (P<0.01). In those mothers who were working less than 3 months there were a higher mean birth weight (P<0.01). Also the mean birth weight decreased due to the hours of standing during a day.ConclusionWomen employment during pregnancy has an important role in low birth weight and preterm labor compared to those who do not work.     

孕产妇暴露因素与小于胎龄儿关系的研究现状

本文通过文献研究,简述了孕产妇暴露因素与小于胎龄儿（SGA）的国内外的研究现状,分析并总结了SGA的结局及其与孕产妇暴露因素之间的关系,为降低SGA的发生、实现优生优育提供重要指导和参考。     

胎龄别新生儿出生体重分析

【目的】 建立以人群为基础的胎龄别新生儿出生体重百分位数修匀曲线。 【方法】 对北京市顺义区医院及顺义区妇幼保健院2009年11月1日-2011年1月21日出生的新生儿进行出生体重的标准化测量,选择符合正常母亲标准的单胎活产新生儿出生体重建立数据库。采用偏度-中位数-变异系数法修匀百分位数。将结果与1986-1987年中国15市新生儿体格发育调查进行比较。 【结果】 共5 068例新生儿纳入到研究中,获得了顺义区正常单胎活产新生儿胎龄别出生体重P3,P10,P25,P50,P75,P90,P97修匀曲线。性别差异具统计学意义(P<0.05)。其中小于胎龄儿发生率为9.39%,大于胎龄儿发生率为9.21%。与15市调查比较,在35~43周的胎龄别出生体重均数差异具统计学意义(P<0.05)。 【结论】 本研究建立了北京市顺义区胎龄别新生儿出生体重百分位数修匀曲线,为该地区及其它类似地区评估胎儿生长发育提供了较新的参考依据。     

Impact of pregnancy-induced hypertension on birthweight by gestational age

Few studies to date have examined the effect of severe pre-eclampsia, pre-eclampsia, and gestational hypertension on birthweight according to gestational age. We conducted a population-based retrospective cohort study of 16,936 pregnant women in Suzhou, China. Analysis of variance and multivariable linear regression were performed to compare the mean birthweights of babies born to mothers with gestational hypertension, pre-eclampsia, and severe pre-eclampsia with birthweights of infants born to mothers with normal blood pressure at each week of gestation. The differences in mean birthweight between women with severe pre-eclampsia and women with normal blood pressure ranged between -467.7 g and 189.1 g. The birthweights were statistically significantly lower in women with severe pre-eclampsia than in women with normal blood pressure for gestational age categories < or = 35 and 36 weeks. However, after adjustment for confounding variables, the birthweights were not statistically significantly different in women with severe pre-eclampsia when compared with women with normal blood pressure even at < or = 35 and 36 weeks. The differences in mean birthweight between women with pre-eclampsia and women with normal blood pressure ranged between -132.2 g and 174.6 g. These differences were not statistically significant, before or after adjusting for confounding variables. There were no differences in mean birthweight between women with gestational hypertension and women with normal blood pressure. Further analysis suggested that pre-eclampsia and gestational hypertension were associated with increased rates of both small-for-gestational-age and large-for-gestational-age infants. The majority of the babies born to mothers with different types of pregnancy-induced hypertension were appropriate-for-gestational-age or even large-for-gestational-age. In this Chinese population, most babies born to mothers with severe pre-eclampsia or pre-eclampsia and gestational hypertension had similar fetal growth to those born to normotensive mothers.     

Relationship of ergonomic stressors to birthweight and gestational age.

Women in many occupations are exposed to ergonomic stressors (eg, prolonged standing, physical exertion, and long work weeks). After a consideration of the major methodological problems encountered in studying effects of ergonomic stressors on birthweight and gestational age, epidemiologic studies that have addressed this issue are reviewed. No individual ergonomic stressor has been consistently associated with effects on gestational age. However, most studies which have attempted to look at the cumulative effect of several stressors report that women in the highest exposure category are at higher risk of giving birth prematurely. In contrast, data regarding an association with birthweight are more variable, and firm conclusions cannot be drawn. While future studies that assess exposure to ergonomic stressors with a more comprehensive and quantitative approach are needed, current evidence is sufficient to suggest that clinicians should take ergonomic stressors into account in the assessment of their patients' risk for preterm delivery.     

Perinatal mortality in relation to birthweight and gestational age: a registry-based comparison of Northern Norway and Murmansk County, Russia

The objective was to explore how perinatal mortality relates to birthweight, gestational age and optimal perinatal survival weight for two Arctic populations employing an existing and a newly established birth registry. A medical birth registry for all births in Murmansk County of North-West Russia became operational on 1st January 2006. Its primary function is to provide useful information for health care officials pertinent to improving perinatal care. The cohort studied consisted of 17,302 births in 2006-07 (Murmansk County) and 16,006 in 2004-06 (Northern Norway). Birthweight probability density functions were analysed, and logistic regression models were employed to calculate gestational-age-specific mortality ratios. The perinatal mortality rate was 10.7/1000 in Murmansk County and 5.7/1000 in Northern Norway. Murmansk County had a higher proportion of preterm deliveries (8.7%) compared to Northern Norway (6.6%). The odds ratio (OR) of risk of mortality (Northern Norway as the reference group) was higher for all gestational ages in Murmansk County, but the largest risk difference occurred among term deliveries (OR 2.45, 95% confidence interval 1.45, 4.14) which hardly changed on adjustment for maternal age, parity and gestation. Proportionately, more babies were born near (± 500 g) the optimal perinatal survival weight in Murmansk County (67.2%) than in Northern Norway (47.6%). The observed perinatal mortality was higher in Murmansk County at all birthweight strata and at gestational ages between weeks 25 and 42, but the adjusted risk difference was most significant for term deliveries.     

The relationship between third trimester maternal weight gain,hematologic status and infant birthweight in Liberian mothers

In 1982, WHO estimated that 20 million infants had low birthweights (LBW) (i.e., <2500 g or 5.5 lb). Most were born in developing countries. Yet for Africa, few studies have examined the relationship between maternal nutrition and birth outcomes. Over 540 hospital records were examined to 1) estimate the proportion of LBW infants. Between 23 and 80 women were studied prospectively to: 2) examine the effects of maternal health complaints on pregnancy outcomes, 3) examine the relationship between weight gain during the 3rd trimester and pregnancy outcome, and 4) determine a weight gain associated with a favorable birthweight range for this sample of women. Results show a positive relationship between birthweight and 6th month maternal Hb values. A 3rd trimester gain of 6.62 kg (14.6 lb) is correlated with a favorable pregnancy outcome. Education was positively associated with 6th month pregnancy weights. Public health workers should concentrate both on iron deficiency anemia and weight gain during the last trimester to increase the chances for successful pregnancy outcomes.     

The quality and completeness of birthweight and gestational age data in computerized birth files.

Computerized birth files compiled by the State of North Carolina for the years 1975-1977 were analyzed for omissions and inaccuracies. A wide range in the per cent missing values was found for different data items, from essentially none missing (birthweight, sex, race) to about 20 per cent missing (gestational age, paternal social data). Recorded birthweight showed the expected skewing from a normal distribution. The only demonstrable inaccuracy was in the form of digit preference, probably causing errors of +/- 1 oz (28.3 g). Reported gestational ages were more suspect, falling outside the range of biologically plausible gestation length in 2.8 per cent of cases. An additional 1.5 per cent of gestational ages were found to be misdated by four to 20 weeks based on the observed bimodal weight distributions among births of the same reported gestational age. Hospitals of various sizes and administrative affiliations submitted records with missing or inaccurate gestational age data with roughly equal frequency. These records were found to come from a socio-demographically high-risk subpopulation. The implications of elimination of incomplete or erroneous birth record data in perinatal epidemiologic research are discussed.