Low Birth Weight Across Generations

Objectives: This study sought to determine the relationship between maternal birth weight, prenatal care usage, and infant birth weight. Methods: Stratified and logistic regression analyses were performed on a dataset of computerized Illinois vital records of White (N = 187,074) and African-American (N = 58,856) infants born between 1989 and 1991 and their mothers born between 1956 and 1975. Results: Among White mothers who received adequate prenatal care, the low birth weight (<2500 g) rate was 4% for infants of former low birth weight mothers (N = 5230) compared to 2.1% for infants of former nonlow birth weight mothers (N = 93,011), relative risk equaled 1.9(1.7–2.2); the population attributable risk of maternal low birth weight was 4.1%. Among African American mothers who received adequate prenatal care, the low birth weight rate was 15% for infants of former low birth weight mothers (N = 2196) compared to 7.2% for infants of former nonlow birth weight mothers (N = 14,607), relative risk equaled 2.1(1.9–2.4); the population attributable risk of maternal low birth weight was 10.9%. The maternal–infant birth weight associations were consistent across all maternal age, education, marital status, and prenatal care categories. Conclusions: Maternal low birth weight is a risk factor for infant low birth weight independent of risk status during the current pregnancy. A greater percentage of low birth weight African American (compared to White) infants are attributable to maternal low birth weight.     

Birth Weight and Infant Growth: Optimal Infant Weight Gain versus Optimal Infant Weight

Objective: Infant growth assessment often focuses on “optimal” infant weights and lengths at specific ages, while de-emphasizing infant weight gain. Objective of this study was to examine infant growth patterns by measuring infant weight gain relative to birth weight. Methods: We conducted this study based on data collected in a prospective cohort study including 3,302 births with follow up examinations of infants between the ages of 8 and 18 months. All infants were participants in the Louisiana State Women, Infant and Children Supplemental Food Program between 1999 and 2001. Growth was assessed by infant weight gain percentage (IWG%, defined as infant weight gain divided by birth weight) as well as by mean z-scores and percentiles for weight-for-age, length-for-age, and weight-for-length calculated based on growth charts published by the U.S. Centers for Disease Control (CDC). Results: An inverse relationship was noted between birth weight category and IWG% (from 613.9% for infants with birth weights <1500 g to 151.3% for infants with birth weights of 4000 g or more). In contrast, low birth weight infants had lower weight-for-age, weight-for-length z-scores and percentiles compared to normal birth weight infants according to CDC growth charts. Conclusions: Although low birth weight infants had lower anthropometric measures compared to a national reference population, they had significant catch-up growth; High birth weight infants had significant slow-down growth. We suggest that growth assessments should compare infants’ anthropometric data to their own previous growth measures as well as to a reference population. Further studies are needed to identify optimal ranges of infant weight gain.     

Maternal Obesity and Risk of Low Birth Weight,Fetal Growth Restriction,and Macrosomia: Multiple Analyses

The associations between maternal pre-pregnancy obesity and low birth weight (LBW, <2500 g) remain inconclusive. Therefore, birth weight in a Polish prospective cohort of 912 mothers was investigated depending on the pre-pregnancy body mass index (BMI). The whole cohort and the subgroup of gestational weight gain (GWG) in the range of the Institute of Medicine (IOM) recommendations, as well as ‘healthy’ women (who did not develop diabetes or hypertension in this pregnancy) were investigated. Adjusted odds ratios (AOR) of the newborn outcomes (with 95% confidence intervals, CI) for obesity (BMI ≥ 30 kg/m²) vs. normal BMI (18.5−24.9 kg/m²) were calculated using multiple logistic regression. Risk profiles (in the Lowess method) were presented for BMI values (kg/m²) and threshold BMI values were calculated. (1) In the cohort, LBW affected 6.6% of pregnancies, fetal growth restriction (FGR) 2.3%, and macrosomia 10.6%. (2) The adjusted risk of macrosomia was more than three-fold higher for obesity compared to normal BMI in the whole cohort (AOR = 3.21 (1.69−6.1), p < 0.001) and the result was maintained in the subgroups. A 17-fold higher adjusted LBW risk for obesity was found (AOR = 17.42 (1.5−202.6), p = 0.022), but only in the normal GWG subgroup. The FGR risk profile was U-shaped: in the entire cohort, the risk was more than three times higher for obesity (AOR = 3.12 (1.02−9.54), p = 0.045) and underweight (AOR = 3.84 (1.13−13.0), p = 0.031). (3) The risk profiles showed that the highest BMI values were found to be associated with a higher risk of these three newborn outcomes and the threshold BMI was 23.7 kg/m² for macrosomia, 26.2 kg/m² for LBW, and 31.8 kg/m² for FGR. These results confirm the multidirectional effects of obesity on fetal growth (low birth weight, fetal growth restriction, and macrosomia). The results for LBW were heavily masked by the effects of abnormal gestational weight gain.     

Maternal Serum Albumin Redox State Is Associated with Infant Birth Weight in Japanese Pregnant Women

Background: Plasma albumin (ALB) reflects protein nutritional status in rats, but it is not clear whether it is associated with dietary protein insufficiency in pregnant women and/or their risk of low birth weight delivery. This study aimed to investigate whether maternal serum ALB redox state reflects maternal protein nutritional status and/or is associated with infant birth weights. Methods: The relationship between the serum reduced ALB ratio and infant birth weight was examined in an observational study of 229 Japanese pregnant women. A rat model simulating fetal growth restriction, induced by protein-energy restriction, was used to elucidate the relationship between maternal nutritional status, maternal serum ALB redox state, and birth weight of the offspring. Results: In the human study, serum reduced ALB ratio in the third trimester was significantly and positively correlated with infant birth weight. In the rat study, serum reduced ALB ratio and birth weight in the litter decreased as the degree of protein-energy restriction intensified, and a significant and positive correlation was observed between them in late pregnancy. Conclusions: Maternal serum reduced ALB ratio in the third trimester is positively associated with infant birth weight in Japanese pregnant women, which would be mediated by maternal protein nutritional status.     

常、微量元素与胎儿宫内发育迟缓关系的研究

目的 探讨常、微量元素与胎儿宫内发育迟缓(IUGR)间的关系.方法 孕晚期测定71名孕妇母血、脐血、羊水中微量元素水平,其中IUGR组21例,对照组35例,巨大儿组15例.结果 IUGR组母血清Zn,Se,Mn,Fe,Mg,Cr明显低于对照组(P＜0.05);Cd,Pb,Ni水平明显高于对照组;巨大儿组母血清Fe含量亦明显低于对照组(P＜0.05);三组间Ca,Ti,Co,Li无明显差别.IUGR组脐血清Se,Mn,Cd,Fe,Cu,Mg明显低于对照组;Pb,Ni明显高于对照组;三组间Zn,Ca,Ti,Co,Li无明显差别.IUGR组羊水Zn,Se,Mn,Fe明显低于对照组,三组间Ca,Co无明显差别.结论 常、微量元素与胎儿发育关系密切,Zn,Se,Mn,Fe,Mg,Cu,Cr缺乏可致胎儿宫内发育迟缓,Cd,Pb,Ni升高可致低体重儿.     

Pre-pregnancy Body Mass Index, Gestational Weight Gain, and Other Maternal Characteristics in Relation to Infant Birth Weight

Objectives Infant birth weight is influenced by modifiable maternal pre-pregnancy behaviors and characteristics. We evaluated the relationship among pre-pregnancy body mass index (BMI), gestational weight gain, and infant birth weight, in a prospective cohort study. Methods Women were enrolled at ≤20 weeks gestation, completed in-person interviews and had their medical records reviewed after delivery. Infant birth weight was first analyzed as a continuous variable, and then grouped into Low birth weight (LBW) (<2,500 g), normal birth weight (2,500–3,999 g), and macrosomia (≥4,000 g) in categorical analysis. Pre-pregnancy BMI and gestational weight gain were categorized based on Institute of Medicine BMI groups and gestational weight gain guidelines. Associations among infant birth weight and pre-pregnancy BMI, gestational weight gain, and other factors were evaluated using multivariate regression. Risk ratios were estimated using generalized linear modeling procedures. Results Pre-pregnancy BMI was independently and positively associated with infant birth weight (β = 44.7, P = 0.001) after adjusting for confounders, in a quadratic model. Gestational weight gain was positively associated with infant birth weight (β = 19.5, P < 0.001). Lower infant birth weight was associated with preterm birth (β = −965.4, P < 0.001), nulliparity (β = −48.6, P = 0.015), and female babies (β = −168.7, P < 0.001). Less than median gestational weight gain was associated with twice the risk of LBW (RR = 2.04, 95% CI 1.34–3.11). Risk of macrosomia increased with increasing pre-pregnancy BMI and gestational weight gain (P for linear trend <0.001). Conclusions These findings support the need to balance pre-pregnancy weight and gestational weight gain against the risk of LBW and macrosomia among lean and obese women, respectively.     

Modifiable Risk Factors for Low Birth Weight and Their Effect on Cerebral Palsy and Mental Retardation

Objective: to estimate the effect of modifiable risk factors on low birth weight and two of its sequelae—cerebral palsy and mental retardation. Methods: The population attributable risk percent (PARP) was used as a measure of effect. A literature search was conducted to determine estimates of the percent of CP and MR attributable to low birth weight. Data from the 1996–1997 Georgia Pregnancy Risk Assessment Monitoring System (PRAMS), a population based surveillance system, were used to estimate the percent of low birth weight attributable to modifiable risk factors. The PARP was calculated for smoking and unwanted conception. Results: Unwanted pregnancy and smoking were statistically significant risk factors for LBW. Four percent of all LBW births were attributable to unwanted pregnancy. If all unwanted pregnancies were prevented, 13% of cases of CP (27 cases per year in GA) and 14% of cases of MR (151 cases per year in GA) would be prevented. In wanted or mistimed pregnancies, 6% of LBW births were attributable to smoking. If all smoking during wanted or mistimed pregnancy was prevented, an additional 2.5% (5 cases) of CP and an additional 0.8% (8 cases) of MR would be prevented in Georgia each year. If all unwanted pregnancies and all smoking during wanted or mistimed pregnancies were prevented, 1692 LBW births could be prevented per year and the rate of LBW in Georgia would fall from 7.6% to 6.8%. Additionally, 32 cases of cerebral palsy and 159 cases of mental retardation could be prevented each year in Georgia. Conclusions: The PARP approach is useful in estimating the benefit of evidence-based prevention services. Preventing unwanted pregnancy and smoking during pregnancy would substantially reduce the burden of cerebral palsy and mental retardation in Georgia.     

极低出生体重儿的体温管理

目的探讨体温管理干预对极低出生体重儿的护理效果。方法收集46例极低出生体重儿,将其随机分为对照组和观察组各23例,两组患儿均接受常规护理,观察组辅以体温管理。对比两组患儿的护理效果。结果观察组护理效果显著优于对照组（P〈0．05）。结论采用体温管理有利于改善极低出生体重儿的临床症状,可降低病死率。     

Maternal Serum Preconception Polychlorinated Biphenyl Concentrations and Infant Birth Weight

Background

Prenatal and postnatal polychlorinated biphenyl (PCBs) exposure has been associated with decrements in fetal and infant growth and development, although exposures during the preconception window have not been examined despite recent evidence suggesting that this window may correspond with the highest serum concentrations.

Objectives

We assessed maternal serum PCB concentrations at two sensitive developmental windows in relation to birth weight.

Methods

Serum samples were collected from 99 women as they began trying to become pregnant (preconception) and after a positive pregnancy test (prenatal); 52 (53%) women gave birth and represent the study cohort. Using daily diaries, women recorded sexual intercourse, menstruation, and home pregnancy test results until pregnant or up to 12 menstrual cycles with intercourse during the estimated fertile window. With gas chromatography with electron capture, 76 PCB congeners were quantified (nanograms per gram serum) and subsequently categorized by purported biologic activity. Serum PCBs were log-transformed and entered both as continuous and categorized exposures along with birth weight (grams) and covariates [smoking (yes/no), height (inches), and infant sex (male/female)] into linear regression.

Results

A substantial reduction in birth weight (grams) was observed for women in the highest versus the lowest tertile of preconception antiestrogenic PCB concentration (β = −429.3 g, p = 0.038) even after adjusting for covariates (β = −470.8, p = 0.04).

Conclusions

These data reflect the potential developmental toxicity of antiestrogenic PCBs, particularly during the sensitive preconception critical window among women with environmentally relevant chemical exposures, and underscore the importance of PCB congener–specific investigation.     

Birth Weight following Pregnancy during the 2003 Southern California Wildfires

Background: In late October 2003, a series of wildfires exposed urban populations in Southern California to elevated levels of air pollution over several weeks. Previous research suggests that short-term hospital admissions for respiratory outcomes increased specifically as a result of these fires.Objective: We assessed the impact of a wildfire event during pregnancy on birth weight among term infants.Methods: Using records for singleton term births delivered to mothers residing in California's South Coast Air Basin (SoCAB) during 2001-2005 (n = 886,034), we compared birth weights from pregnancies that took place entirely before or after the wildfire event (n = 747,590) with those where wildfires occurred during the first (n = 60,270), second (n = 39,435), or third (n = 38,739) trimester. The trimester-specific effects of wildfire exposure were estimated using a fixed-effects regression model with several maternal characteristics included as covariates.Results: Compared with pregnancies before and after the wildfires, mean birth weight was estimated to be 7.0 g lower [95% confidence interval (CI): -11.8, -2.2] when the wildfire occurred during the third trimester, 9.7 g lower when it occurred during the second trimester (95% CI: -14.5, -4.8), and 3.3 g lower when it occurred during the first trimester (95% CI: -7.2, 0.6).Conclusions: Pregnancy during the 2003 Southern California wildfires was associated with slightly reduced average birth weight among infants exposed in utero. The extent and increasing frequency of wildfire events may have implications for infant health and development.     

孕晚期维生素营养状况与胎儿宫内生长迟缓的病例对照研究

对９７名胎儿宫内生长迟缓（ＩＵＧＲ）孕妇和１３３名对照进行了孕晚期膳食摄入量及血液维生素水平的对比研究，结果发现：ＩＵＧＲ孕妇热能、蛋白质摄入不足，Ｃａ、ＶＢ＿２缺乏，ＶＡ、ＶＢ＿１摄入低下，血清维生素Ｅ含量只有对照组一半（Ｐ＜０．０１）；多元逐步回归分析表明孕母血清维生素Ｅ与婴儿多个出生时生长指标其回归系数为正。红细胞转酮酶活力（ＴＰＰ％）和谷胱甘肽还原酶活性系数（ＡＣ）值两组比较差别无显著性，但均提示两组孕妇有硫胺素及核黄素缺乏（ＴＰＰ％＞１６％，ＡＣ值＞１．２）。     

胎儿生长受限的DNA甲基化研究进展

胎儿生长受限(FGR)是较严重的妊娠合并症,不仅对胎儿在妊娠期的健康造成威胁,使其围生期患病率和死亡率增加;还对胎儿出生后产生重要影响,使其成年后远期心血管、代谢性疾病等多种疾病的发病率有所增加。近年来研究发现,DNA甲基化改变在FGR的发生发展中起着重要作用,就DNA甲基化在FGR领域的研究现状和进展加以综述,通过分析引起FGR的异常DNA甲基化危险因素及DNA甲基化与FGR胎儿成年后疾病的相关性改变,对DNA甲基化与FGR发生、发展的可能的相关机制进行探讨,为FGR的生物学发展和成年后疾病风险度的评估研究提供重要线索,为预防、诊断和治疗提供一种新思路。     

院外延续护理在极低出生体重早产儿中的应用

目的探讨延续护理在极低出生体重早产儿(VLBWI)出院后生长中的作用。方法选取2010年1月至2011年12月期间在我院出生的VLBWI 50例并分为两组。24例对照组患儿出院后由家长自行护理;26例观察组患儿出院后由我科资深护士进行延续护理,直至患儿1周岁。比较两组患儿出院后至1周岁期间的再入院率、死亡率,观察两组患儿1周岁时的体格发育、神经发育情况。结果随访期间再入院率的比较观察组显著低于对照组(P<0.05),但死亡率差异无统计学意义(P>0.05)。两组存活患儿1周岁时的体格发育均近似于正常婴儿。观察组存活患儿1周岁MDI评分、PDI评分表现明显好于对照组(P<0.05)。观察组患儿MDI<70、PDI<70、脑瘫、失聪、神经发育损害例数及发生率均低于对照组,但两组间无统计学差异(P>0.05)。结论院外延续护理可降低VLBWI的再入院率和死亡率,改善患儿的神经发育。     

Maternal Exposure to Particulate Air Pollution and Term Birth Weight: A Multi-Country Evaluation of Effect and Heterogeneity

Background: A growing body of evidence has associated maternal exposure to air pollution with adverse effects on fetal growth; however, the existing literature is inconsistent.Objectives: We aimed to quantify the association between maternal exposure to particulate air pollution and term birth weight and low birth weight (LBW) across 14 centers from 9 countries, and to explore the influence of site characteristics and exposure assessment methods on between-center heterogeneity in this association.Methods: Using a common analytical protocol, International Collaboration on Air Pollution and Pregnancy Outcomes (ICAPPO) centers generated effect estimates for term LBW and continuous birth weight associated with PM₁₀ and PM_2.5 (particulate matter ≤ 10 and 2.5 µm). We used meta-analysis to combine the estimates of effect across centers (~ 3 million births) and used meta-regression to evaluate the influence of center characteristics and exposure assessment methods on between-center heterogeneity in reported effect estimates.Results: In random-effects meta-analyses, term LBW was positively associated with a 10-μg/m³ increase in PM₁₀ [odds ratio (OR) = 1.03; 95% CI: 1.01, 1.05] and PM_2.5 (OR = 1.10; 95% CI: 1.03, 1.18) exposure during the entire pregnancy, adjusted for maternal socioeconomic status. A 10-μg/m³ increase in PM₁₀ exposure was also negatively associated with term birth weight as a continuous outcome in the fully adjusted random-effects meta-analyses (–8.9 g; 95% CI: –13.2, –4.6 g). Meta-regressions revealed that centers with higher median PM_2.5 levels and PM_2.5:PM₁₀ ratios, and centers that used a temporal exposure assessment (compared with spatiotemporal), tended to report stronger associations.Conclusion: Maternal exposure to particulate pollution was associated with LBW at term across study populations. We detected three site characteristics and aspects of exposure assessment methodology that appeared to contribute to the variation in associations reported by centers.     

我国儿童少年生长发育迟缓筛选标准的研究

本研究选择北京、云南两省市5225名6～12岁儿童少年为对象．进行为期一年的追踪研究，在1979～1980年北京等5省市及1985年全国体质调研的基础上．以身高、身高生长速度作为生长发育迟缓的筛选指标，参考国内外有关标准．结合我国临床应用情况，提出我国儿童少年生长发育迟缓筛选标准：凡身高低于同种族、同地区、同性别、同年龄身高的第三百分位数（P3）或身高生长速度小于4cm／年者为生长发育迟缓筛选阳性者。年龄范围：7～12岁。     

Characteristics of Gut Microbiota in Small for Gestational Age Infants with Very Low Birth Weight

Small for gestational age (SGA) birth is associated with high rates of mortality and morbidity in preterm infants. The aim of this preliminary observational study was to investigate the difference in gut microbiota between SGA and appropriate for gestational age (AGA) preterm infants with very low birth weight (VLBW). We included 20 VLBW preterm infants (SGA, n = 10; AGA, n = 10) in this study. Stool samples were collected on days 7, 14, and 30 after birth. We performed 16S ribosomal DNA sequencing to compare microbiota composition between both groups. The SGA group exhibited a lower abundance of Klebsiella on day 14 (SGA, 0.57%; AGA, 7.42%; p = 0.037). On day 30, the SGA group exhibited a lower abundance of Klebsiella (SGA 3.76% vs. AGA 16.05%; p = 0.07) and Enterobacter (SGA 5.09% vs. AGA 27.25%; p = 0.011) than the AGA group. Beta diversity demonstrated a separation of the bacterial community structure between both groups on day 30 (p = 0.019). The present study revealed that a distinct gut microbiota profile gradually develops in SGA preterm infants with VLBW during the early days of life. The role of changes in gut microbiota structure warrants further investigation.