Evaluation of four maternal smoking questions

Low birthweight in term singletons mediates the association between maternal smoking intensity exposure status and immediate neonatal intensive care unit admission: the E-value assessment

BACKGROUND

Research investigating the wellbeing of term neonates in the United States is scarce. The objectives of this study were to estimate the prevalence of low birthweight (LBW) and neonatal intensive care unit (NICU) admission among term singletons in association with maternal smoking intensity exposure status, to explore LBW as a mediator linking smoking to immediate newborn NICU transfer/admission, and to assess the potential impact of unmeasured confounding in effect estimates.

METHODS

The Natality File of live births registered in the United States in 2016, the first year that all 50 states implemented the revised 2003 standard birth certificate, was restricted to singleton term births (37-41 completed weeks gestation). The prevalence of LBW (< 2500 g) and NICU transfer/admission was estimated across maternal demographic characteristics and smoking intensity status in early and in late pregnancy. Mediation analyses, based on the counterfactual approach, were conducted to examine the total effect (TE), controlled direct effect (CDE), natural direct (NDE) and indirect effects (NIE), and the percentage mediated through LBW. The E-values based on effect size estimates and on lower-bounds of 95% confidence intervals (CIs) assessed the potential impact of unmeasured confounding.

RESULTS

Nearly 6.8% of women smoked in early and in late pregnancy, most (36.4%) smoked at high intensity (≥ 10 cigarettes /day) and had the highest prevalence of LBW (6.7%) and NICU transfer/admission (7.0%). For the largest smoking intensity exposure category, the estimate of the TE was 1.68 (95% CI: 1.63, 1.73), of the NDE was 1.56 (95% CI: 1.51, 1.61), of the NIE was 1.08 (95% CI:1.07, 1.09), and the percentage mediated by LBW was 17.6%. The E-values for association estimates and for the lower-bounds of 95% CIs demonstrated the minimum strength of the potential unmeasured confounding necessary to explain away observed associations.

CONCLUSIONS

These findings fill a gap on the prevalence of LBW and NICU transfer/admission in term neonates of mothers who smoke and on the role of LBW linking to NICU placement, which could be used to update practitioners, to implement smoking cessation interventions, monitor trends, and to inform planning and allocation of healthcare resources.

Prevalence and patterns of cigarette smoking before and during early and late pregnancy according to maternal characteristics: the first national data based on the 2003 birth certificate revision, United States, 2016

BACKGROUND

The objective of this study was to examine the prevalence of smoking by intensity status before pregnancy and during early (first and second trimester) and late (third trimester) pregnancy according to race/ethnicity, age, and educational attainment of women who gave birth in the United States in 2016.

METHODS

This cross-sectional study was based on the 2016 National Center for Health Statistics (NCHS) Natality File of 3,956,112 live births, the first year that it became 100% nationally representative. Self-reported smoking data were used to create new seven smoking intensity status categories to capture natural variability in smoking patterns during pregnancy and to identify maternal smokers by race/ethnicity, age, and educational attainment. The risk of smoking at low and high intensity in early pregnancy was estimated in multivariable logistic regression analyses.

RESULTS

Nearly 9.4% of women reported smoking before pregnancy and 7.1% during pregnancy, both at high and low intensity, and smoking rates were higher in the first trimester (7.1%) than in the second (6.1%) or the third (5.7%) trimester. Non-Hispanic White women, women 20-24 years old, and women with less than a high school education were the strongest predictors of smoking anytime during pregnancy. The odds of smoking in early pregnancy at high intensity were 88% lower (aOR 0.12, 95% CI: 0.11, 0.13) for Hispanic women, compared to non-Hispanic White women; 16% higher (aOR 1.16, 95% CI: 1.12, 1.21) for women 20-24 years old and 16% lower (aOR 0.84, 95% CI: 0.80, 0.89) for women ≥35 years old, compared to women 25-29 years old; as well as 13% higher (aOR 1.13, 95% CI: 1.09, 1.18) for women with less than a high school education and 92% lower (aOR 0.08, 95% CI: 0.08, 0.09) for women with a bachelor's degree or higher, compared to women with a high school diploma.

CONCLUSIONS

Despite the high prevalence of high intensity smoking before and during pregnancy, future intervention strategies need to focus on the proportion of low intensity quitters and reducers, who are ready to stop smoking. Continual monitoring of trends in smoking intensity patterns is necessary, including neonatal outcomes over time.

Smoking cessation during pregnancy: a population-based study

OBJECTIVE

To measure the prevalence of smoking cessation during pregnancy and to identify factors associated with its occurrence.

METHODS

The present survey included all puerperal women living in the municipality of Rio Grande, RS, whose birth occurred between January 1 and December 31, 2013. A single standardized questionnaire was applied, in the hospital, within 48 hours of delivery. Multivariate analysis was performed using Poisson regression with robust variance.

RESULTS

The prevalence of smoking cessation among the 598 parturients studied was 24.9% (95%CI 21.5-28.6). After adjusting for confounding factors, mothers aged 13 to 19 years (PR = 1.76; 95%CI 1.13-2.74), who had higher family income (PR = 1.83; 95%CI, 1.23-2.72), higher educational level (PR = 2.79; 95%CI 1.27-6.15), higher number of prenatal appointments (PR = 1.84; 95%CI 1.11-3.05), and who did not smoke in the previous pregnancy (PR = 2.93; 95% CI, 1.95-4.41) presented a higher prevalence ratio of smoking cessation.

CONCLUSIONS

Although pregnancy is a window of opportunity for smoking cessation, the rate of cessation was low. The prevalence of cessation was higher among mothers with lower risk of complications, suggesting the need for interventions prioritizing pregnant women of lower socioeconomic levels.

Maternal Smoking Among Women With and Without Use of Assisted Reproductive Technologies

OBJECTIVE

To estimate smoking prevalence during the year before pregnancy and during pregnancy and adverse outcomes among women who delivered infants with and without assisted reproductive technology (ART) using linked birth certificates (BC) and National ART Surveillance System (NASS) data.

METHODS

Data were analyzed for 384,390 women and 392,248 infants born in Massachusetts and Michigan during 2008-2009. Maternal smoking prevalence was estimated using smoking indicated from BC by ART status. For ART users, to evaluate underreporting, prepregnancy smoking was estimated from BC, NASS, or both sources. Effect of prenatal smoking on preterm and mean birthweight (term only) for singleton infants were examined by ART status.

RESULTS

Maternal smoking prevalence estimates were significantly lower for ART users than nonusers (prepregnancy = 3.2% vs. 16.7%; prenatal = 1.0% vs. 11.1%, p < 0.05). When combining smoking information from BC and NASS, prepregnancy smoking prevalence estimates for ART users could be as high as 4.4% to 6.1%. Adverse effects of smoking on infant outcomes in ART pregnancies were consistent with the effects seen in non-ART pregnancies, specifically decline in infant birthweight and increase in preterm delivery, although association between smoking and preterm was not significant.

CONCLUSION

A low, but substantial proportion of ART users smoked before and during pregnancy. As ART users are highly motivated to get pregnant, it should be clearly communicated that smoking can decrease fertility and adversely affect pregnancy outcomes. Continued efforts are needed to encourage smoking cessation and maintain tobacco abstinence among all women of reproductive age.

Home visitation program effectiveness and the influence of community behavioral norms: a propensity score matched analysis of prenatal smoking cessation

Background

The influence of community context on the effectiveness of evidence-based maternal and child home visitation programs following implementation is poorly understood. This study compared prenatal smoking cessation between home visitation program recipients and local-area comparison women across 24 implementation sites within one state, while also estimating the independent effect of community smoking norms on smoking cessation behavior.

Methods

Retrospective cohort design using propensity score matching of Nurse-Family Partnership (NFP) clients and local-area matched comparison women who smoked cigarettes in the first trimester of pregnancy. Birth certificate data were used to classify smoking status. The main outcome measure was smoking cessation in the third trimester of pregnancy. Multivariable logistic regression analysis examined, over two time periods, the association of NFP exposure and the association of baseline county prenatal smoking rate on prenatal smoking cessation.

Results

The association of NFP participation and prenatal smoking cessation was stronger in a later implementation period (35.5% for NFP clients vs. 27.5% for comparison women, p < 0.001) than in an earlier implementation period (28.4% vs. 25.8%, p = 0.114). Cessation was also negatively associated with county prenatal smoking rate, controlling for NFP program effect, (OR = 0.84 per 5 percentage point change in county smoking rate, p = 0.002).

Conclusions

Following a statewide implementation, program recipients of NFP demonstrated increased smoking cessation compared to comparison women, with a stronger program effect in later years. The significant association of county smoking rate with cessation suggests that community behavioral norms may present a challenge for evidence-based programs as models are translated into diverse communities.

Screening for use of alcohol, tobacco and cannabis in pregnancy using self-report tools

The World Health Organization has identified substance use in the top 20 risk factors for ill health. Risks in pregnancy are compounded, with risk to the woman's health, to pregnancy progression and on both the foetus and the newborn. Intrauterine exposure can result in negative influences on offspring development, sometimes into adulthood. With effectively two patients, there is a clear need for antenatal screening. Biomarker reliability is limited and research efforts have been directed to self-report tools, often attempting to address potential lack of veracity if women feel guilty about substance use and worried about possible stigmatization. Tools, which assume the behaviour, are likely to elicit more honest responses; querying pre-pregnancy use would likely have the same effect. Although veracity is heightened if substance use questions are embedded within health and social functioning questionnaires, such tools may be too lengthy clinically. It has been proposed that screening only for alcohol and tobacco, with focus on the month pre-pregnancy, could enable identification of all other substances. Alternatively, the Revised Fagerstrom Questionnaire could be used initially, tobacco being highly indicative of substance use generally. The ASSIST V.3.0 is readily administered and covers all substances, although the pregnancy 'risk level' cut-off for tobacco is not established. Alcohol tools - the 4Ps, TLFB and 'drug' CAGE (with E: query of use to avoid withdrawal) - have been studied with other substances and could be used. General psychosocial distress and mental ill-health often co-exist with substance use and identification of substance use needs to become legitimate practice for obstetric clinicians.

Increasing support for smoking cessation during pregnancy and postpartum: results of a randomized controlled pilot study

OBJECTIVES

We examined the feasibility and effectiveness of an intervention to mobilize women in the social networks of pregnant smokers to support smoking cessation.

METHODS

This study was conducted in St. Paul, Minnesota, and Columbus, Ohio, from 2005 through 2007. Pregnant smokers (n=82) identified a woman in their social network to help them quit smoking. The resulting dyads were randomized to either intervention (n=54) or control (n=28) conditions. Supporters of intervention subjects received monthly contacts from a counselor about providing effective support; supporters in the control condition were not contacted. Interviews with subjects and supporters were conducted at baseline, end of pregnancy and 3 months postpartum.

RESULTS

Compared with control subjects, intervention group subjects reported that their supporters had provided support behaviors more frequently and were more committed to helping them quit. There was a non-significant trend for more validated quits in the intervention group at the end of pregnancy: 13.0% vs. 3.6% among the controls. Quit rates decreased to 9.3% in the intervention group and 0% in the control group at 3 months postpartum.

CONCLUSIONS

Increasing the frequency and quality of support from a woman in the smoker's social network is a promising prenatal smoking cessation strategy.

Prenatal smoking prevalence ascertained from two population-based data sources: birth certificates and PRAMS questionnaires, 2004

OBJECTIVES

This study provided a population-based estimate of the prevalence of smoking during pregnancy by combining information from two data sources: birth certificates (BCs) and a self-administered questionnaire.

METHODS

We analyzed data from 39,345 women who delivered live births in one of 24 states and responded to a questionnaire from the Pregnancy Risk Assessment Monitoring System (PRAMS), an ongoing, state- and population-based surveillance system. We compared prevalence of smoking during pregnancy based on the BC, the PRAMS questionnaire, and the two data sources combined. Data were weighted to represent all women delivering live births in each of the 24 states during 2004.

RESULTS

The combined estimate indicated that 15.1% of women reported smoking during pregnancy, whereas the BCs alone reported 10.4% and the PRAMS questionnaires alone reported 13.4%.

CONCLUSIONS

Based on the combined BC and PRAMS questionnaire data, the number of infants exposed to tobacco in-utero may be 31% higher than is currently reported on the BCs. Combining the data from the two different sources led to higher ascertainment of prenatal smoking.

Exposure to cigarette smoke in utero: comparison of reports from mother and daughter

BACKGROUND

Smoking during pregnancy has been associated with asthma, obesity, and decreased cognitive functioning in the offspring. To study the role of in utero smoking exposure in offsprings' adult health outcomes, it may be necessary to rely upon reports by the offspring themselves.

METHODS

We studied 34,949 mother-daughter pairs participating in the Nurses' Health Study II for whom data on the daughter's early passive cigarette smoke exposure had been obtained from both mother and daughter. We calculated sensitivity and specificity of daughter's early exposure to smoke (using mother's report as the gold standard), as well as kappa statistics. Mother and daughter reports were also analyzed as risk factors for asthma and birthweight to demonstrate face validity.

RESULTS

Sensitivity of daughters' reported prenatal exposure ranged from 74% to 85%, while specificity was between 90% and 95% (kappa = 0.72-0.81). Daughter's reported childhood exposure as a proxy for mother's report of smoking during pregnancy had a sensitivity of 89% and specificity of 88%. Results were similar for daughter's report of father's smoking during her childhood. Maternal smoking during pregnancy is consistently associated with reductions in offspring birthweight, and with asthma risk in offspring. The daughter's risk of being very low (<1500 g) or low birthweight (<2500 g) or of having asthma were similar when exposure was defined according to mother's report, daughter's report of fetal smoke exposure, and daughter's report of mother's smoking during childhood.

CONCLUSIONS

Daughter's report of mother's smoking prenatally and in childhood are good proxy measures for mother's own report of smoking during pregnancy.

Annual summary of vital statistics: 2006

US births increased 3% between 2005 and 2006 to 4,265,996, the largest number since 1961. The crude birth rate rose 1%, to 14.2 per 1000 population, and the general fertility rate increased 3%, to 68.5 per 1000 women 15 to 44 years. Births and birth rates increased among all race and Hispanic-origin groups. Teen childbearing rose 3% in 2006, to 41.9 per 1000 females aged 15 to 19 years, the first increase after 14 years of steady decline. Birth rates rose 2% to 4% for women aged 20 to 44; rates for the youngest (10-14 years) and oldest (45-49) women were unchanged. Childbearing by unmarried women increased steeply in 2006 and set new historic highs. The cesarean-delivery rate rose by 3% in 2006 to 31.1% of all births; this figure has been up 50% over the last decade. Preterm and low birth weight rates also increased for 2006 to 12.8% and 8.3%, respectively. The 2005 infant mortality rate was 6.89 infant deaths per 1000 live births, not statistically higher than the 2004 level. Non-Hispanic black newborns continued to be more than twice as likely as non-Hispanic white and Hispanic infants to die in the first year of life in 2004. For all gender and race groups combined, expectation of life at birth reached a record high of 77.9 years in 2005. Age-adjusted death rates in the United States continue to decline. The crude death rate for children aged 1 to 19 years decreased significantly between 2000 and 2005. Of the 10 leading causes of death for children in 2005, only the death rate for cerebrovascular disease was up slightly from 2000, whereas accident and chronic lower respiratory disease death rates decreased. A large proportion of childhood deaths, however, continue to occur as a result of preventable injuries.

Back to the future? A critical commentary on the 2003 U.S. National standard certificate of live birth

Vital statistics documents for the United States have been revised approximately decennially throughout the past century. In this commentary we review the contents of the 2003 revision of the national standard certificate of live birth, focusing on changes from the certificates in use nationally since 1989, and identifying strengths and weaknesses of key data elements. Additional federal-state partnership funding is imperative to support the transition to the new standard certificates, and to ensure a focus on data quality at the state and national levels.

Maternal cigarette smoking during pregnancy increases the risk of having a child with a congenital digital anomaly

BACKGROUND

The U.S. Natality database from 2001 and 2002 was used to investigate the relationship between maternal cigarette smoking during pregnancy and the risk of having a child with polydactyly, syndactyly, or adactyly.

METHODS

The records of 6,839,854 live births were examined to identify 5171 newborns with isolated polydactyly, syndactyly, or adactyly and 10,342 controls with no congenital anomalies.

RESULTS

Maternal cigarette use during pregnancy was associated with a significantly elevated risk of having a child with a congenital digital anomaly (unadjusted odds ratio, 1.33; 95 percent confidence interval, 1.21 to 1.47; p < 0.0001). Univariate analysis indicated that maternal marital status and medical risk factors (anemia, cardiac disease, lung disease, diabetes, hydramnios/oligohydramnios, pregnancy-associated hypertension, incompetent cervix, previous preterm or small-for-gestational-age infant, and rhesus factor sensitization) were potential confounding factors. After adjustment for these variables, the odds ratio remained significant (adjusted odds ratio, 1.31; 95 percent confidence interval, 1.18 to 1.45; p < 0.0001). Cigarette consumption per day was divided into four groups: no smoking, 1 to 10 cigarettes per day, 11 to 20 cigarettes per day, and 21 or more cigarettes per day. A statistically significant dose-response relationship was found when comparing each smoking category with the no-smoking reference group: 1.29 (95 percent confidence interval, 1.15 to 1.46), 1.38 (95 percent confidence interval, 1.12 to 1.71), and 1.78 (95 percent confidence interval, 0.97 to 3.26), respectively. Increased cigarette smoking during pregnancy resulted in an elevated risk of having a child with polydactyly, syndactyly, or adactyly.

CONCLUSIONS

This is the largest study to date to investigate specifically the association between maternal cigarette smoking and the risk of having a newborn with a congenital digital anomaly. The elevated odds ratio for tobacco use and the significant trend in the dose-response relationship suggests smoking during pregnancy may be an important preventable risk factor for these common congenital differences.

Breastfeeding duration and perinatal cigarette smoking in a population-based cohort

OBJECTIVES

We examined the association between breastfeeding duration and maternal smoking before, during, and after pregnancy.

METHODS

Data from the 2000-2001 Oregon Pregnancy Risk Assessment Monitoring System were used. Early weaning was defined as not breastfeeding at 10 weeks postpartum.

RESULTS

At 10 weeks after pregnancy, 25.7% of mothers who initiated breastfeeding no longer breastfed. After controlling for confounders, quitters (mothers who quit smoking during pregnancy and maintained quit status after pregnancy) and postpartum relapsers (mothers who quit smoking during pregnancy and resumed smoking after delivery) did not have significantly higher risk for early weaning than nonsmokers. However, persistent smokers (mothers who smoked before, during, and after pregnancy) were 2.18 times more likely not to breastfeed at 10 weeks (95% confidence interval=1.52, 2.97). Women who smoked 10 or more cigarettes per day postpartum (i.e., heavy postpartum relapsers and heavy persistent smokers) were 2.3-2.4 times more likely to wean their infants before 10 weeks than were nonsmokers.

CONCLUSIONS

Maternal smoking is associated with early weaning. Stopping smoking during pregnancy and decreasing the number of cigarettes smoked postpartum may increase breastfeeding duration.

Self-reported smoking, cotinine levels, and patterns of smoking in pregnancy

Non-pregnant adult smokers generally exhibit fairly stable smoking behaviour over time. In studies of this population, cotinine assays are considered a 'gold standard' measure of exposure to cigarette smoke; current smoking status can be validated with high sensitivity and specificity. In contrast, there is substantial within-person fluctuation in pregnancy smoking, as women try repeatedly to quit or cut down. As a result, cotinine measures may be of limited use for validation of amount smoked, as they are informative only about recent exposure, vary with individual smoking topography and are dependent on time lapsed since the last cigarette smoked. Thus, in reproductive epidemiology, where timing, intensity and duration of exposure are critical, self-reported history of cigarette consumption may be a more relevant fetal exposure than current smoking status. If there were substantial within-person variation over the course of pregnancy, numerous measures of cotinine would be needed to characterise patterns of fetal exposure and would not be feasible in many studies. We examined self-reported smoking patterns and compared them to patterns of urinary cotinine levels in a prospective study of 998 pregnant women, recruited 1988-92. Fluctuations in smoking were considerable and, while cotinine measures and self-reported number of cigarettes were highly correlated at any given time point across women (r=0.70), the within-person correlation between the patterns of self-reported number of cigarettes and cotinine levels was weaker (r=0.33). For researchers interested in fetal outcomes in which intensity and timing of exposure are critical, we conclude that self-reported variations in smoking during pregnancy may be a valid way to characterise detailed patterns of fetal exposure in epidemiological studies.

Divergent trends in maternal cigarette smoking during pregnancy: United States 1990-99

While examination of causes for trends in smoking have largely focused on how changes have occurred with maternal age and, less commonly, time period, little is known as to how age, period and birth cohort interact on trends in the prevalence of smoking during pregnancy. We performed a population-based, retrospective cohort study based on the vital statistics records comprised of White (n=24,499,629) and Black (n = 5,096,625) women delivering in the United States in 1990-99. Smoking prevalence rates were derived by seven 5-year maternal age groups (15-19 to 45-49 years), two time periods (1990-94 and 1995-99), and eight 5-year maternal birth cohorts (1945-49 to 1980-84) after adjusting for the confounding effects of gravidity, education, marital status, and lack of prenatal care through multivariable logistic regression models. The prevalence of smoking was 17.3% among Whites, and 13.5% among Blacks, with substantial variations by age, time period, and birth cohort. The rate declined with increasing age among Whites during the 1990-94 and 1995-99 periods. Among Blacks, the rates increased steeply with advancing age up to 25-29 years and began to decline thereafter. Smoking rates declined among both Whites and Blacks with increasing birth cohort within each age strata. These rates were highest among multigravid women (gravida > or = 2), and lowest among primigravid women. The rates among Whites declined with increasing maternal age for each gravida. Among Blacks, smoking rates for each gravida increased with advancing age up to 25-29 years, and plateaued among older women. Variation in smoking prevalence by age, time period, and birth cohort provides impetus for designing interventions to reduce smoking. Such studies should not only consider cross-sectional trends, but also the divergent patterns by age and cohort among women of different race/ethnic groups and gravidity.

Can support and education for smoking cessation and reduction be provided effectively by midwives within primary maternity care?

OBJECTIVE

To test the hypothesis that appropriate interventions delivered by midwives within usual primary maternity care, can assist women to stop or reduce the amount they smoke and facilitate longer duration of breast feeding.

DESIGN, SETTING AND PARTICIPANTS

In a cluster randomised trial of smoking education and breast-feeding interventions in the lower North Island, New Zealand, midwives were stratified by locality and randomly allocated into a control group and three intervention groups. The control group provided usual care. Midwives in the intervention groups delivered either a programme of education and support for smoking cessation or reduction, a programme of education and support for breast feeding or both programmes. Sixty-one midwives recruited a total of 297 women.

INTERVENTIONS

Structured programmes provided by midwives.

FINDINGS

Women receiving only the smoking cessation or reduction programme were significantly more likely to have reduced, stopped smoking or maintained smoking changes than women in the control group, at 28 weeks and 36 weeks gestation. Women receiving both the smoking cessation and breast-feeding education and support programmes were significantly more likely than women in the control group to have changed their smoking behaviour at 36 weeks gestation. There was no difference in rates of cessation or reduction between the groups in the postnatal period. There was no difference in rates of full breast feeding between the control and intervention groups for women who planned to breast feed.

KEY CONCLUSIONS

Education and support by midwives, as part of primary midwifery, can facilitate smoking cessation and reduction during pregnancy.

Trends in smoking before, during, and after pregnancy in ten states

BACKGROUND

While trends in smoking prevalence during pregnancy are known, little is known about trends in quitting during pregnancy and resuming smoking after pregnancy.

OBJECTIVES

This study examined the trends in and correlates of quitting during pregnancy and resuming smoking after pregnancy.

METHODS

We used population-based random surveys of recent mothers in ten U.S. states (total of 115,000 women) conducted between 1993 and 1999.

RESULTS

Although the prevalence of smoking 3 months before pregnancy was stable at around 26%, quitting during pregnancy rose from 37% to 46% between 1993 and 1999. Adjusted for maternal and state characteristics, the odds of quitting during pregnancy increased 51% between 1993 and 1999 (odds ratio [OR]=1.51; 95% confidence interval [CI]=1.08-2.12). Approximately half of the women who quit smoking during pregnancy resumed smoking within 6 months postpartum. Primiparous, privately insured, college-educated women are more likely to quit and least likely to resume smoking after delivery, compared to multiparous, Medicaid-insured, and high school-educated women. Teenaged women are more likely to quit, but also more likely to resume smoking than older women.

CONCLUSIONS

The increase in quit rates during pregnancy is encouraging, but the lack of any change in smoking before pregnancy or in postpartum relapse rates suggests that permanent changes in maternal smoking will require additional focus.

Maternal smoking and birth defects: validity of birth certificate data for effect estimation

OBJECTIVES

The authors sought to assess the validity of birth certificate data for estimating the association between maternal smoking and birth defects. The US standard birth certificate includes check boxes for maternal smoking and for 21 congenital anomalies. The sensitivity and specificity of birth certificate data have been studied, but previous studies have not addressed the validity of these data for estimating the association between birth defects and maternal smoking or other risk factors.

METHODS

US public-use natality data (1997-1998) were used to calculate the prevalence ratio (adjusted for maternal age, race/ethnicity, and education) for the association between maternal smoking and 13 defects/defect categories. All analyses were restricted to 45 states, New York City, and the District of Columbia because they collect both maternal smoking and birth defect data.

RESULTS

Maternal smoking was associated with an increased prevalence of hydrocephaly (adjusted prevalence ratio [PR] = 1.24; 95% confidence interval [CI] = 1.08, 1.43), microcephaly (PR 1.47; 95% CI 1.15, 1.88), omphalocele/gastroschisis (PR 1.37; 95% CI 1.22, 1.53), cleft lip/palate (PR 1.35; 95% CI 1.25, 1.45), clubfoot (PR 1.62; 95% CI 1.49, 1.75), and polydactyly/syndactyly/adactyly (PR 1.33; 95% CI 1.23, 1.43 ). Previous studies have indicated an association between maternal smoking and gastroschisis, oral clefts, and clubfoot with effect estimates of similar magnitude to this study.

CONCLUSIONS

These findings suggest that birth certificate data may be useful for exploratory or corroborative studies estimating the association between birth defects and some risk factors recorded on birth certificates.

Factors associated with smoking cessation among U.S. pregnant women

OBJECTIVES

This study examines smoking and smoking cessation behaviors among U.S. pregnant women and seeks to identify the sociodemographic correlates of smoking cessation in pregnancy.

METHODS

The 1998 NHIS Pregnancy and Smoking supplement was analyzed, including 5288 U.S. women (weighted to represent 13,714,358 women) who gave birth to a liveborn infant in the past 5 years. Four categories of smoking behavior were analyzed: nonsmoking at last pregnancy, persistent smoking throughout pregnancy, attempting unsuccessfully to quit during pregnancy, and successfully quitting during pregnancy. Logistic regression was used to isolate risk factors for each of the smoking behaviors and to examine factors associated with attempted and successful cessation.

RESULTS

The women most likely to attempt to quit smoking in pregnancy were Hispanic women (OR = 3.09) and women who have smoked for less than 10 years (OR = 2.75 for women aged 18-24.) In general, for the groups at highest risk of smoking at the start of pregnancy, the odds of being a persistent smoker were higher than the odds of being an unsuccessful quitter, which in turn were higher than the odds of quitting successfully. The factors associated with attempts to quit included Hispanic ethnicity, higher education, above-poverty income, and shorter duration of smoking, while the combined effect of age and smoking duration was the only one significantly associated with successful quitting. In every age group, longer smoking duration was associated with lower likelihood of attempting to quit as well as successful quitting.

CONCLUSIONS

The factors most strongly associated with attempts to quit smoking were Hispanic ethnicity and the combined effect of age and smoking duration. Future smoking cessation and relapse prevention programs should be developed, taking into consideration the critical factors of age, ethnicity, income, geography, and addiction.

Recommended cessation counselling for pregnant women who smoke: a review of the evidence

OBJECTIVE

To review the evidence base underlying recommended cessation counselling for pregnant women who smoke, as it applies to the steps identified in the Agency for Healthcare Research and Quality's publication, Treating tobacco use and dependence: a clinical practice guideline.

DATA SOURCES

Secondary analysis of literature reviews and meta-analyses.

DATA SYNTHESIS

A brief cessation counselling session of 5-15 minutes, when delivered by a trained provider with the provision of pregnancy specific, self help materials, significantly increases rates of cessation among pregnant smokers. This low intensity intervention achieves a modest but clinically significant effect on cessation rates, with an average risk ratio of 1.7 (95% confidence interval 1.3 to 2.2). There are five components of the recommended method-"ask, advise, assess, assist, and arrange".

CONCLUSIONS

We recommend these evidence based procedures be adopted by all prenatal care providers. The use of this evidence based intervention is feasible in most office or clinic settings offering prenatal care and can be implemented without inhibiting other important aspects of prenatal care or disrupting patient flow. If implemented widely, this approach has the potential to achieve an important reduction in a number of adverse maternal, infant, and pregnancy outcomes and to reduce associated, excess health care costs.

Measurement and definition for smoking cessation intervention research: the smoke-free families experience. Smoke-Free Families Common Evaluation Measures for Pregnancy and Smoking Cessation Projects Working Group

The measures, definitions, and processes used in the Smoke-Free Families clinical trials to assure consistent measurement and reporting of various aspects of the trials are described. Definitions of current smokers at different points in the pregnancy, levels of addiction, biological verification, cessation, stages of change, and intervention approaches are presented along with the rationale underlying their adoption and development.

The effect of implementing a more comprehensive screening for substance use among pregnant women in North Carolina

OBJECTIVES

Substance use during pregnancy causes significant morbidity and mortality. Screening for substance use provides opportunity for intervention and treatment, but is often overlooked in prenatal care with today's fiscal climate and preconceived ideas about who uses substances. The purpose of this study was to determine the effect of implementing a more comprehensive screening procedure for identifying substance-using pregnant women.

METHODS

Two hundred randomly selected prenatal patients screened using the old procedure for substance use during pregnancy were compared to 400 randomly selected patients screened after implementation of a new, more detailed screening procedure. The old screening approach included three check-boxes concerning substance use during pregnancy: one for "Smoking/alcohol," one for "Drug use (any)," and one for "Drug addiction/alcoholism." The new screening procedure included more detailed questions about the frequency of cigarette, alcohol, and illegal drug use during pregnancy.

RESULTS

Compared with the old approach, the new screening protocol increased reporting of smoking/alcohol use from 21% to 72% (relative risk = 2.63, 95% confidence interval = 2.231, 3.108); reporting of any drug use from 12% to 18% (relative risk = 1.07, 95% confidence interval = 1.002, 1.150); and reporting of alcoholism/drug abuse from 0% to 6% (relative risk = 1.06, 95% confidence interval = 1.038, 1.090).

CONCLUSIONS

Our study suggests that more detailed screening using direct questions concerning the amount and frequency of substance use increases reporting of prenatal substance use as compared to screening approaches using only "yes/no" style check boxes.