Risk factors associated with very low birth weight in a low-income population

This study aimed to identify risk factors associated with very low birth weight in a general hospital in Caxias do Sul, Rio Grande do Sul State, Brazil. This was a case-control study of 200 newborns with birth weight from 500 to 1,499 g (cases) and 400 with birth weight from 3,000 to 3,999 g (controls). Infants were from singleton pregnancies, and their mother had received prenatal care at public health services. The dependent variable was birth weight, and independent variables included socioeconomic status, schooling, and gestational and birth status. Univariate and multivariate analyses were performed with a 5% level of significance. Mortality in very low birth weight newborns was 32.5%. The limits of viability were 600 g for birth weight and 26 weeks for gestational age. Variables related to very low birth weight were: maternal age > 35 years (p = 0.01), lack of prenatal care (p < 0.0001), illness during the index pregnancy (p = 0.03), maternal hypertension (p = 0.007), hospitalization during pregnancy (p < 0.0001), and prior history of low birth weight (p < 0.0001). Many premature births were due to avertable factors.     

Change in observed birth weight associated with change in maternal cigarette smoking

Using data collected by the National Collaborative Perinatal Project of the National Institute of Neurological and Communicative Disorders and Stroke, the author paired on characteristics of their first study pregnancy 319 white women who reported a change in smoking habits for two successive pregnancies with 319 women who reported no change in smoking behavior. Matching was based upon similar birth weight, interval between births, smoking behavior, sex, and parity of the first of two study births. Divergent smoking behavior for each pair by the time of the second study birth allowed assessment of smoking as a treatment effect. Members of each pair who started smoking prior to the second birth while not smoking for the first, had infants with an average birth weight of 67 g less than infants of their controls who did not start smoking and 36 g less than their previous infant. Among infants whose mothers reported smoking prior to the first study birth, a significant increase in birth weight was observed over infants of controls for women who quit smoking prior to the second study birth (average, 169 g). Taken at face value, this rebound in birth weight is not consistent with an immutable, innate predisposition to lower birth weight among those disposed to smoking.     

Risk factors for low birth weight in a socio-economically disadvantaged population: parity,marital status,ethnicity and cigarette smoking

Low birth weight (LBW) is a public health problem, because it is associated with increased risk of morbidity and mortality. The principal aim of this study was to assess risk factors for LBW in a large multi-ethnic and socio-economically disadvantaged population. Data from 3242 mothers, who attended the Well Baby Clinic (Southwestern Sydney, Australia) for the first time, were analysed in relation to their demographic characteristics and socio-economic indices. The overall birthweight was 3377 ± 577 g (mean ± SD). In multiple linear regression analysis, smoking during pregnancy, marital status, parity, and country of birth were independently associated with birth weight. According to this analysis, lower birth weight was associated with mothers who had smoked during pregnancy (by 215.2 ± 18.6 g), who were single (46.9 ± 21 g), and of Asian background (108.5 ± 38.2 g). However, higher parity was associated with significantly higher birth weight. The presence of each factor was coded as 1 and the absence, 0. A risk score was then derived by summing up the individual scores. When birth weight was classified as low birth weight (defined as those with birth weight being less than 2500 g) or normal birth weight, the overall prevalence of LBW was 1.9%. Each unit increase in the risk score was associated with a 1.9-fold (95% confidence interval: 1.5–2.6) increase in the risk of LBW. These data suggest that apart from marital status, ethnicity and parity, maternal smoking is the single most important preventable risk factors for LBW.     

母源性吸烟对新生儿出生体重、头围、身长及储存铁影响的研究

目的 探讨母源性吸烟对新生儿出生体重、头围、身长及储存铁的影响,为提高我国围产保健水平提供理论依据。方法 以150名产妇及其新生儿为研究对象,按WHO推荐的吸烟频率分类将产妇分为不吸烟组,偶尔吸烟组以及每日吸烟组,于孕晚期进行膳食调查,计算其每日铁摄入量。测量新生儿的出生体重、身长、头围,并采集产妇外周血及新生儿脐带血,检测血清铁蛋白(SF)及血清可溶性转铁蛋白受体(sTfR)水平,计算全身铁(TBI)水平。结果 产妇在孕晚期的每日铁摄入量差异无统计学意义;不吸烟组新生儿出生体重明显高于两个吸烟组(P均<0.05);两个吸烟组新生儿的头围及身长差异无统计学意义(P均>0.05);不吸烟组产妇sTfR水平明显高于两个吸烟组(P均<0.001),SF和TBI水平均低于两个吸烟组(P均<0.05);不吸烟组新生儿sTfR水平明显低于两个吸烟组(P均<0.001),SF和TBI水平明显高于两个吸烟组(P均<0.001)。结论 母源性吸烟可引起产妇自身储存铁升高,而使新生儿出生体重以及储存铁降低。     

Parental attitudes about a pregnancy predict birth weight in a low-income population

BACKGROUND: Low birth weight remains the primary cause of neonatal morbidity and mortality in the United States. We examined whether maternal happiness about a pregnancy, in addition to her report of the father's happiness, predicts birth weight and risk for low birth weight (<2,500 g). METHODS: In this prospective cohort study, the mother's report of her and her partner's happiness about the pregnancy was measured before 21 weeks' gestation on a scale from 1 to 10 (1 to 3 unhappy, 4 to 7 ambivalent, or 8 to 10 happy). "Mother reports partner happier" occurred when the mother perceived the father's happiness score at least 5 points greater than her own. Information on birth weights and maternal sociodemographic, medical, and psychosocial factors were obtained from surveys and medical records. RESULTS: Of 162 live births, 9 were low birth weight (5.6%). Compared with women who reported happiness with the pregnancy, risk for low birth weight was greater when the mother reported partner happier about the pregnancy (relative risk 10.0, 95% confidence interval, 3.1-32.4). This predictor of birth weight remained significant in multivariate linear regression analyses (coefficient = -472 g, SE = 171 g, P = .007) after adjustment for other known predictors of birth weight. CONCLUSIONS: Maternal report of greater partner happiness about a pregnancy is associated with birth weight and appears to define low- and high-risk subgroups for low birth weight in a low-income population. Further study in larger samples is needed to confirm our findings and to assess whether maternal report of greater partner happiness is itself a modifiable factor or is a marker for other factors that might be modified with targeted interventions.     

Mortality attributable to cigarette smoking in a cohort study in Japan

We conducted this study to estimate the association and population attributable risk (PAR) of smoking with all-cause and cause-specific mortality based on a general prospective cohort study in Japan. A total of 8,129 subjects (3,996 males and 4,133 females) aged 40 or over were analyzed. The follow-up period was from 1986 to 2003. Smoking habit was classified into three categories of never smoker, former smoker, and current smoker. The Cox proportional hazard model was used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI). We also estimated the PAR of smoking, and calculated the 95% CI of PAR based on the bootstrap procedure. A total of 112,151 person-years were counted for 8,129 subjects over an average of 13.7 years of follow-up. The results showed that smoking increased the risk of dying from all cancers, cardiovascular, and respiratory diseases in both sexes. For all causes of death, smokers had a HR of 1.30 (95% CI: 1.09, 1.54), PAR of 13.1% (95% CI: 7.6, 22.3) in males, and HR of 1.81 (95% CI: 1.43, 2.29), and PAR of 6.1% (95% CI: 3.1, 9.3) in females compared to never smokers. These results confirm an increased risk of mortality from all causes, as well as from all cancers, cardiovascular disease, and respiratory disease in relation to smoking habit. Smoking is responsible for a considerable proportion of deaths due to all causes as well as cause-specific deaths. Population-based antismoking programs should be implemented to reduce such avoidable deaths.     

The role of maternal stature in ethnic differences inperinatal mortality and low birth weight

Perinatal mortality, low birth weight and maternal height have been studied in Asians and non-Asians in Bradford. Perinatal death, low birth weight and short stature are all more common in Asians and the latter may be partly responsible for the other parameters.     

Racial/ethnic differences in smoking, other risk factors, and low birth weight among low-income pregnant women, 1978-1988

Because of the adverse effects of low birth weight (LBW) on infant morbidity and mortality, one of the 1990 health objectives for the nation has been to reduce the incidence of LBW to 5% among all live births in the United States. Public health surveillance of cigarette smoking during pregnancy has demonstrated an association between smoking and an increased risk of LBW, defined as birth weight of less than 2,500 g. For the period 1978-1988, information on nearly 248,000 women from CDC's Pregnancy Nutrition Surveillance System showed an LBW rate of 6.9%, a high prevalence of smoking during pregnancy (29.7%); and a strong association between smoking during pregnancy and the likelihood of delivering an LBW infant in all age, racial/ethnic, and prepregnancy weight groups. The risk of LBW was greater for smokers than for nonsmokers (9.9% versus 5.7%), creating an excess LBW risk of 4.2% associated with smoking. Overall, the average birth-weight deficit related to smoking was 178 g. Among both smokers and nonsmokers, black women had a higher percentage of LBW infants than did white women, and the risk of LBW related to smoking was greater among black women. That risk tended to increase with age, especially among women with low pregravid weight. Major reductions in LBW might be achieved if smoking were eliminated among pregnant women.     

Proportions of cancer deaths attributable to cigarette smoking in women

Over two-thirds of a million American women mostly over age 45 were enrolled in a prospective mortality study in 1982 and followed up for four years. In this time period 1,527 women died of six smoking-related cancer sites: oral cavity, esophagus, pancreas, larynx, lung, and bladder. Age-adjusted death rates in nonsmokers were used to obtain smoking-attributable risks and numbers of deaths due to these six cancers. Among current smokers, 601 deaths (85.5% of current smokers' deaths) were attributable to cigarette smoking, and among former smokers 284 (69.3% of ex-smokers' deaths) were attributable to smoking. Cigarette smoking accounted for 885 excess deaths at these sites, giving a population-attributable risk of 57.9%. Over three-quarters of these excess deaths were due to lung cancer. Cigarette smoking, despite increases in smoking cessation, is still responsible for well over half of the deaths from these six types of cancer in women.     

Dose-response of birth weight to various measures of maternal smoking during pregnancy

Thus far little is known about the dose-response relationship between birth weight and the amount of maternal smoking during pregnancy. The purpose of this report is to describe the effects of smoking intensity, duration, and timing on birth weight with the use of three measures of exposure: self-reported daily consumption, self-reported cumulative consumption, and salivary thiocyanate. Data were obtained on 867 single live-born infants and their mothers who participated in a randomized anti-smoking intervention trial. Smoking was measured for the women at about 15 weeks gestation and again during the eighth month. Although all indicators of dose, as derived from early or late pregnancy smoking measures, were significantly associated with birth weight, whether or not the mother had quit smoking by the time of the 8th month follow-up was almost as predictive as any dose variable. For women who quit smoking before 30 weeks gestation, neither the duration nor the amount of smoking earlier in pregnancy was an important determinant of birth weight.     

Adolescent maternal weight gain and low birth weight: a multifactorial model

Maternal weight gain is one of the most important independent predictors of infant birth weight and interacts with other maternal characteristics, including age, so that infant birth weight reaches a plateau at a higher level of maternal weight gain for young adolescents than for adults. It has been suggested that encouraging young adolescents to gain larger amounts of weight during pregnancy may be one way to decrease their risk of low-birth-weight deliveries. This recommendation may be premature because the mechanisms underlying the interaction between maternal age and weight gain are incompletely understood and may include such diverse factors as incomplete maternal growth, reproductive immaturity, diminished maternal body size, nutritional deficiencies, socioeconomic and behavioral factors, and maternal emotional stress. This review summarizes the literature on adolescent maternal weight gain and infant birth weight and discusses the importance of considering a multifactorial model in reformulating the weight-gain recommendations for pregnant adolescents.     

孕妇被动吸烟与低出生体重关系的Meta分析

目的分析孕妇孕早期和不同孕期被动吸烟对新生儿低出生体重的影响。方法通过Meta分析方法分析孕妇被动吸烟与新生儿低出生体重之间的关系。对NCBI、OVID-MEDLINE、CNKI、VIP以及CBM数据库进行检索(截止日期为2008年4月),结果报告合并OR值及95%CI。结果共获得26篇文献,其中队列研究20篇,病例对照研究6篇。总体分析,孕妇被动吸烟的合并效应值OR=1.65(95%CI:1.39～1.97);调整合并效应值OR=1.60(95%CI:1.25～2.05);最低和最高暴露量的合并效应值分别为OR=1.53(95%CI:1.14～2.04)和OR=2.53(95%CI:1.46～4.36);孕早期暴露的合并效应值OR=1.12(95%CI:0.82～1.55),没有统计学意义。结论孕妇被动吸烟增加新生儿低出生体重的危险性;孕中晚期可能是被动吸烟效应的敏感期;被动吸烟的阈值是否存在尚不明确。     

2015年青岛市归因于吸烟的癌症疾病负担研究

目的 分析青岛市2015年归因于吸烟的癌症疾病负担,为进一步控烟策略提供科学依据。方法 利用青岛市2015年人口数据、死因监测数据,以吸烟影响比表示吸烟的暴露分布,估计归因于吸烟的癌症死亡人数及其造成的期望寿命损失。结果 青岛市2015年归因于吸烟的癌症死亡数为4 148人（占癌症总死亡人数的29.13%）,其中男性3 195人（33.00%）,女性953人（20.92%）。死亡人数伴随年龄组增大呈现上升趋势,在45~岁年龄组明显增加,在60~岁年龄组达到顶点。在与吸烟相关的癌症中,吸烟归因分值最高的5种癌症依次为肺癌（60.04%）、鼻咽癌（37.95%）、口腔癌（35.41%）、食管癌（35.14%）和膀胱癌（14.93%）;归因于吸烟的死亡数最高的5种癌症依次为肺癌（3 122人）、肝癌（339人）、食管癌（293人）、胃癌（185人）和胰腺癌（55人）。青岛市居民归因于吸烟的癌症死亡所导致的期望寿命损失为0.87岁,其中男性1.19岁,女性0.45岁。结论 青岛市居民归因于吸烟的癌症疾病负担较重,降低吸烟率,保护不吸烟者免受二手烟污染等控烟措施势在必行。     

Costs of maternal conditions attributable to smoking during pregnancy

Context: Despite known adverse health effects, many women continue to smoke during pregnancy. Public attention has now focused on the economic as well as health effects of this behavior.Objective: To estimate health care costs associated with smoking-attributable cases of placenta previa, abruptio placenta, ectopic pregnancy, preterm premature rupture of the membrane (PPROM), pre-eclampsia, and spontaneous abortion.Design: Pooled odds ratios were used with data on total cases to estimate smoking-attributable cases. Estimated average costs for cases of ectopic pregnancy and spontaneous abortion were used to estimate smoking-attributable health care costs for these conditions. Incremental costs, or costs above those for a “normal” delivery, were used to estimate smoking-attributable costs of placenta previa, abruptio placenta, PPROM, and pre-eclampsia associated with delivery.Setting: National estimates for 1993.Participants: Data from the National Hospital Discharge Survey (NHDS) and claims data from a sample of large, self-insured employers across the country.Results: Smoking-attributable costs ranged from $1.3 million for PPROM to $86 million for ectopic pregnancy. Smoking during pregnancy apparently protects against pre-eclampsia and saves between $36 and $49 million, depending on smoking prevalence. Over all conditions smoking-attributable costs ranged from $135 to $167 million.Conclusions: Smoking during pregnancy is a preventable cause of higher health care costs for the conditions studied. While smoking during pregnancy was found to be protective against pre-eclampsia and, hence, saves costs, the net costs were still positive and significant. Effective smoking-cessation programs can reduce health care costs but clinicians will perhaps need to manage increased cases of pre-eclampsia in a cost-effective manner.     

Is maternal asthma a risk factor for low birth weight?

The association between history of asthma in the mother and low birth weight (<2,500 g) was studied in 2,929 primary schoolchildren, randomly selected from three areas of the Lazio Region, Italy, and enrolled in a cross-sectional survey to assess their health status in relation to environmental factors. A history of asthma in the mother was associated with a higher prevalence of low birth weight, with a crude OR of 2.95 (95% CI 1.10–6.72). After stratification for other variables, an association was still present only for males (OR 4.13; 95% CI 1.01–12.53), when mothers had smoked in pregnancy (OR 8.02; 95% CI 1.63–32.28) and were resident in an industrial town (OR 10.21; 95% CI 2.69–32.27). An OR of 6.43 was also found when mothers belonged to low social class, but the 95% CI included the unity. These results suggest that a history of asthma in the mother is a risk factor for low birth weight, but only when other adverse factors are concurrently present.     

Effect of maternal work activity on preterm birth and low birth weight

The association of the prolonged standing required by certain jobs with the rate of preterm births and low birth weight deliveries was examined in New Haven, Connecticut, between 1980 and 1982. In a sample of 1,206 women, the rate of preterm births (births occurring less than 37 weeks from the last menstrual period) was higher among women with jobs requiring prolonged standing (7.7%) compared with those with sedentary (4.2%) or active jobs (2.8%). The odds of preterm delivery in the standing group was 2.72 (95% confidence interval of 1.24-5.95). A significant association between standing on the job and preterm birth was demonstrated when adjustment was made for the following variables in a logistic regression model: parity, smoking, education, caffeine use, marijuana use, race, gestational age at interview, and marital status. The low birth weight (less than 2,500 g) rate was higher among those in the standing group (5.5%) compared with those in the sedentary (4.0%) and active groups (4.0%), but this association was not significant when confounding factors were controlled.     

母亲孕期生活习惯与低出生体重关系病例对照研究

目的 探讨母亲孕期生活习惯与早产低体重和足月低体重的关系。方法 运用整群抽样方法,采用自编孕期健康调查问卷对2015年8月-2016年5月在广东省江门市14家医院住院分娩的1 964名产妇及其新生儿进行调查,应用二水平logistic回归模型进行多因素分析。结果 早产低体重组、足月低体重组和正常体重组分别为294、289和1 381名;3组被动吸烟率分别为36.39%、38.41%和33.09%,饮酒率分别为2.72%、3.11%和1.59%。在调整了其他因素后,与母亲孕期基本不锻炼相比,孕期体育锻炼1~3次/周（AOR=0.58,95%CI=0.40~0.86）和≥4次/周（AOR=0.54,95%CI=0.37~0.78）均是早产低体重的保护因素;在足月低体重儿中,与母亲孕期平均每天使用电子设备时长<1 h相比,使用1~2 h（AOR=0.61,95%CI=0.40~0.93）、3~4 h（AOR=0.55,95%CI=0.35~0.86）和>4 h（AOR=0.57,95%CI=0.37~0.89）的母亲其新生儿发生低体重的危险均降低;母亲孕期被动吸烟（AOR=1.36,95%CI=1.02~1.81）是足月低体重的危险因素。结论 母亲孕期生活习惯会影响低体重儿的发生,且在早产低体重儿和足月低体重儿中存在差异,应采取相应的干预措施降低低体重儿的发生。     

The effects of maternal smoking, physical stature, and educational attainment on the incidence of low birth weight

Data from the 1980 National Natality Survey were used to investigate the effects of maternal smoking, height, weight, and educational attainment on the incidence of low birth weight among white non-Hispanic married mothers aged 20-34 years, live birth order 1-3. Using multiple logistic regression to control for the effects of infant's sex, live birth order, and maternal age, women with less than 12 years education have a low birth weight odds ratio of 2.38 and women with 12 years have a low birth weight odds ratio of 1.24 relative to women with 13 or more years. After further controlling for height, weight, and smoking, these odds ratios are reduced to 1.59 and 1.11, respectively. The majority of the reduction can be attributed to differences in smoking among the education groups. Women with low education are more likely to have smoked prior to pregnancy, more likely to smoke heavily, and less likely to stop smoking during pregnancy. The odds of low birth weight increases by 26% for every five additional cigarettes smoked per day. If all women in the study population stopped smoking during pregnancy, the incidence of low birth weight would be expected to decline by 35% for those with less than 12 years education, by 20% for those with 12 years, and by 11% for those with more than 12 years. The effects of the independent variables were also estimated for two components of low birth weight: below 2,000 grams and 2,000-2,499 grams. Although the nonresponse rate for the National Natality Survey was 20%, a comparison of mail and telephone respondents suggests that the impact of nonresponse on the estimates of the logistic coefficients is minimal.