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.     

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.     

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。     

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.     

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.     

A prospective study of the attributable risk of cancer due to cigarette smoking.

BACKGROUND. The goals of this study were to measure the impact of cigarette smoking on cancer incidence and to determine the attributable risk of cancer due to smoking. METHODS. A cigarette smoking history was obtained from 8006 Japanese-American men examined from 1965 through 1968. After 22 years, 1389 incident cases of cancer were identified. There were 212 men with lung cancer; 202 with oral, esophageal, laryngeal, pancreatic, renal, ureteral, or bladder (oral-bladder) cancer; and 975 with cancer at other sites. RESULTS. Current smokers at time of examination had a higher incidence than nonsmokers for each of the three cancer site categories. Eighty-five percent of lung cancer cases diagnosed among current and never smokers can be attributed to cigarette smoking. The attributable risks were 46%, 16%, and 29%, respectively, for oral-bladder cancers, other cancers, and all cancers combined. In turn, the corresponding attributable risks were 60%, 26%, 13%, and 21% in comparing current smokers with past smokers. CONCLUSIONS. Current smokers can greatly reduce their risk of cancer, especially lung cancer, if they quit smoking.     

妊娠期PM_(2.5)暴露与新生儿低出生体重的meta分析

目的定量分析和评价妊娠期PM_(2.5)暴露对新生儿低出生体重的影响。方法通过计算机联机检索国内外文献数据库,采用meta分析对妊娠期PM_(2.5)暴露与新生儿低出生体重关系的研究进行整合分析。经异质性检验后选择合适的效应模型进行统计量的计算合并,同时检验结果的稳健性及是否存在发表偏倚。结果最终筛选出16篇文献,meta分析结果显示,整个妊娠期PM_(2.5)暴露浓度每升高10μg/m~3,新生儿发生低出生体重的风险增加9.53%(95%CI:3.92%~14.84%);妊娠早、中、后期PM_(2.5)暴露浓度每升高10μg/m~3,新生儿发生低出生体重的风险分别增加6.77%(95%CI:-4.08%~17.40%),5.83%(95%CI:-2.02%~13.98%),2.96%(95%CI:-3.05%~9.53%)。敏感性分析发现,所获得的研究结果相对稳定可靠,但在分析整个妊娠期PM_(2.5)暴露对新生儿低出生体重的影响时仍存在一定的发表偏倚。结论整个妊娠期PM_(2.5)的暴露可能增加新生儿发生低出生体重的风险。     

The costs of health damage and productivity losses attributable to cigarette smoking in Germany

Background: Smoking causes significant health damage and mayincur a significant economic burden to society. This study investigatesthe years of potential life lost, the direct medical costs andthe Indirect costs of cigarette smoking in Germany. Methods:Using the concept of attributable risks and the prevalence-basedapproach, smoking-attributable mortality and morbidity werecalculated for 1993. Neoplasms, cardiovascular diseases, respiratorydiseases, perinatal diseases and burn deaths were considered.Attributable risks stem from the literature and were processedin an epidemiological model. Costs were estimated from a societalperspective. Direct costs were mainly calculated based on routineutilization and expenditure statistics and indirect costs werecalculated according to the human capital approach. Results:Twenty-two percent of all male and 5% of all female deaths aswell as 1.5 million years of potential life lost were attributableto smoking. The costs of acute hospital care, in-patient rehabilitationcare, ambulatory care and prescribed drugs were 9.3 billionDEM, of mortality were 8.2 billion DEM and costs due to work-lossdays and early retirement were 16.4 billion DEM (discount rate3%). The total costs added up to 33.8 billion DEM, 415 DEM perinhabitant or 1,599 DEM per current smoker. Sensitivity analysesshowed that including the productivity loss of unpaid work leadsto a strong increase of indirect costs. Conclusions: This studyprovides a conservative estimate of the costs of smoking inGermany. The magnitude is considered sufficient reason to callfor stronger support of cost-effective, smoke-cessation measuresand of anti-smoking policy.     

Prenatal weight gains related to the birth of healthy-sized infants to low-income women

Prepregnancy weight status and weight gain during pregnancy are major independent variables associated with infant birth weight. This study quantitated the influence of weight gain on birth weight and identified rates and total amounts of weight gain related to the birth of healthy-sized infants to healthy low-income women who entered pregnancy underweight, at normal weight, overweight, or obese. Data used in the study were obtained from randomly sampled prenatal health records from Maternal and Infant Care (MIC) projects in Cleveland and Minneapolis. Subsamples of healthy mothers who delivered healthy-sized infants were identified from each sample, and rates and total amounts of weight gain by prepregnancy weight status group were calculated. There were 384 healthy mother and healthy-sized infant pairs in the Cleveland subsample and 75 such pairs in the Minneapolis sample. Multiple regression analysis revealed that the influence of prenatal weight gain and birth weight varied depending on prepregnancy weight status. Prenatal weight gains related to the birth of healthy-sized infants (newborns with birth weights of 3,000 to 4,500 gm) to healthy mothers in the Cleveland MIC sample averaged 33 lb for underweight, 32 lb for normal weight, 29 lb for overweight, and 19 lb for obese women. Except for obese women, rates and total amount of weight gain associated with the birth of healthy-sized infants were equivalent for the two samples.     

The effect of maternal smoking on the relationship between maternal and fetal zinc status and infant birth weight

We have previously reported a trapping of zinc in the placenta directly related to circulating cadmium that comes from cigarette smoke. The purpose of this study was to examine in detail the effect of smoking on (a) the relationship between maternal and fetal zinc status and (b) the relationship between zinc status and birth weight. One hundred and eighteen smokers and 172 nonsmokers without any medical complications during pregnancy were studied. Atomic absorption spectroscopy was used to assess zinc status in maternal and cord vein plasma and red blood cells. Plasma alkaline phosphatase was also determined as an index of zinc status. Thiocyanate was used as an index of smoking status. The data were analyzed using univariate correlations and repeated measures analysis of variance. Infants of smokers had a statistically significant decrease in plasma zinc (5%), alkaline phosphatase (13%), and in cord vein RBC zinc (12%). Furthermore, the results showed an altered relationship between maternal and fetal indices of zinc status and zinc status and birth weight due to maternal smoking. The infant of the nonsmoking mother appears to be able to maintain adequate zinc status due to depletion of maternal zinc. However, it appears that the infant of the smoking mother may be marginally zinc deficient. These findings support studies of zinc supplementation in the pregnancy complicated by smoking.