Smoking and smoking cessation during early pregnancy and its effect on adverse pregnancy outcomes and fetal growth

Smoking cessation Through Optimization of clinical care in Pregnancy: the STOP pragmatic randomized controlled trial

BACKGROUND

Smoking cessation improves pregnancy outcomes, yet there is uncertainty around the efficacy of models of antenatal intervention for smoking cessation in pregnancy.

OBJECTIVE

This study aimed to test the Smoking cessation Through Optimization of clinical care in Pregnancy (STOP) clinic as an antenatal care pathway for smoking cessation in pregnancy. The STOP intervention is a smoking cessation clinic staffed by a dedicated multidisciplinary team of obstetricians, midwives, and smoking cessation practitioners, who provide motivational and psychological support and intensive clinical monitoring of pregnancy.

STUDY DESIGN

This was a pragmatic randomized controlled trial of the STOP clinic compared with routine antenatal care at a tertiary urban maternity hospital delivering >8000 infants per year. The primary outcome measured was continuous abstinence from smoking before 28+0 weeks' gestation, sustained throughout the duration of the pregnancy, and validated using biological measures. The secondary outcomes included maternal and fetal morbidity, delivery and neonatal outcomes, smoking outcomes, and qualitative measures.

RESULTS

A total of 436 women were randomized, with 430 women included in the primary outcome analysis. Women attending the STOP antenatal clinic were more likely to quit smoking compared with those in routine care (odds ratio, 3.62; 95% confidence interval, 1.43-9.17). In addition, women who continued to smoke in the STOP clinic smoked fewer cigarettes daily at the time of delivery compared with controls: 5±4 in the STOP clinic and 7±5 in the control group (odds ratio, 0.28; 95% confidence interval, 0.13-0.59). However, this intervention did not alter postpartum relapse rates (4.3% intervention arm vs 1.5% control arm, not significant) at 4 to 6 months following delivery. The mean birthweight was similar in the intervention and control arms; however, quitters in both groups had infants with significantly higher birthweights compared with those of continued smokers.

CONCLUSION

The STOP antenatal model of care leads to higher smoking cessation rates among pregnant smokers and lower daily cigarette consumption at time of delivery. Currently, there is no defined or dedicated antenatal pathway for pregnant smokers, despite the high-risk nature of their pregnancies. Our findings suggest that improved smoking cessation rates in pregnancy may be achieved using the holistic approach of the STOP model of care.

Timing of Maternal Smoking Cessation and Newborn Weight, Height, and Head Circumference

OBJECTIVE

To examine the relationship between timing of smoking cessation during pregnancy and anthropometric indices of newborns.

METHODS

Mothers and neonates enrolled in the JECS (Japan Environment and Children's Study), a nationwide birth cohort study, were examined. Patients with full-term neonates were included in the analysis, and 73,025 mother-neonate pairs with complete data were identified. The mothers were classified into six groups according to smoking status during pregnancy (nonsmokers [Q1, n=44,198]; ex-smokers who quit before pregnancy [Q2, n=16,461]; ex-smokers who quit in the first trimester [Q3, n=8,948]; ex-smokers who quit in the second trimester [Q4, n=498]; ex-smokers who quit in the third trimester [Q5, n=651]; and smokers who smoked throughout pregnancy [Q6, n=2,269)]). Data on smoking were based on questionnaires administered in the first, second, or third trimester and 1 month after delivery. The primary outcomes were birth weight, height, and head circumference.

RESULTS

Compared with nonsmokers (Q1), no adverse outcomes were observed for ex-smokers who quit before pregnancy (Q2). The mean adjusted weights of male and female neonates were 135 g and 125 g lower, respectively, in Q6 participants than in Q1 participants. Comparing Q1 and Q6 participants, height was 0.6 cm and 0.7 cm smaller for male and female neonates, respectively. Head circumference in neonates of Q6 participants was 0.3 cm and 0.3 cm smaller for male and female neonates, respectively, than that in Q1 participants. Across all three measures, smoking cessation in the first and second trimester reduced the differential in outcomes between nonsmokers and individuals who smoked throughout pregnancy.

CONCLUSION

Smoking during pregnancy is associated with reduced newborn birth weight, height, and head circumference. Earlier smoking cessation during pregnancy reduces the adverse effects of smoking on fetal growth.

The Outcome of Pregnancy Among Tobacco Users in Tertiary Care Hospital of Chhattisgarh Province of India

BACKGROUND

Tobacco use is responsible for numerous adverse pregnancy outcomes for females and their infants. The aim of this study was to explore the adverse outcome of tobacco use among pregnant females.

METHOD

 A cross-sectional study was conducted on 1250 females in the third trimester of pregnancy from April to June 2022, which were exposed to tobacco use in the form of gudaku, tobacco chewing, gutka, or smoking. Complications and outcomes during and after pregnancy were recorded based on self-administered questionnaires. Statistical analysis was performed using the Statistical Package for Social Sciences (SPSS) (IBM SPSS Statistics, Armonk, NY) software version 20.0 for categorical data, frequencies (n) and percentages (%) were calculated, and the chi-square test was used for determining intergroup differences.

RESULTS

 Out of 1250 females, tobacco exposure was present among 429 (34.3%), and 821 (65.7%) had no tobacco exposure. Of 429, 36.10% of females complained about complications such as abortion (1.60%), antepartum hemorrhage (0.90%), congenital anomaly (0.20%), infertility (1.20%), intrauterine fetal death (IUFD) (0.50%), intrauterine growth restriction (IUGR) (0.90%), oligohydramnios (OLIGO) (3.30%), preterm labor (18.40%), premature rupture of membrane (6.30%), and anemia (2.80%), which were slightly higher than the females with no tobacco exposure. In tobacco users, obstructive complications were found to be significant with a p value of 0.0036.

CONCLUSION

Our study concluded that tobacco use could have an adverse effect on their fetus and infants, as well as the pregnant females themselves. Policymakers need to ensure effective strategies that pregnant females, their partners, and close relatives need to have enough knowledge to avoid potential risks.

Changes in e-cigarette and cigarette use during pregnancy and their association with small-for-gestational-age birth

BACKGROUND

Despite increased e-cigarette use, limited research has focused on changes in e-cigarette and combustible cigarette use around pregnancy and the subsequent effects on infant health.

OBJECTIVE

This study aimed to characterize changes in e-cigarette and cigarette use from before to during pregnancy and examine their associations with small-for-gestational-age birth.

STUDY DESIGN

This was a secondary data analysis of 2016-2018 data of the US Pregnancy Risk Assessment Monitoring System. We analyzed women aged ≥18 years who had a recent live birth (unweighted: n=105,438; weighted: n=5,446,900). Women were grouped on the basis of their self-reported e-cigarette and/or cigarette use 3 months before pregnancy (exclusive e-cigarette users, exclusive cigarette smokers, dual users, and nonusers) and change in e-cigarette and cigarette use during pregnancy (continuing use, quitting, switching, and initiating use). Small-for-gestational-age was defined as a birthweight below the 10th percentile for infants of the same sex and gestational age. We described the distributions of women's sociodemographic and pregnancy characteristics in both weighted and unweighted samples. We used multivariable log-binomial regression models to estimate the relative risks for the associations between changes in e-cigarette and cigarette use during pregnancy and risk of small-for-gestational-age, adjusting for significant covariates.

RESULTS

The rates of cessation during pregnancy were the highest among exclusive e-cigarette users (weighted percentage, 80.7% [49,378/61,173]), followed by exclusive cigarette users (54.4% [421,094/773,586]) and dual users (46.4% [69,136/149,152]). Among exclusive e-cigarette users, continued users of e-cigarettes during pregnancy had a higher risk of small-for-gestational-age than nonusers (16.5% [1849/11,206]) vs 8.8% [384,338/4,371,664]; confounder-adjusted relative risk, 1.52 [95% confidence interval, 1.45-1.60]), whereas quitters of e-cigarettes had a similar risk of small-for-gestational-age with nonusers (7.7% [3730/48,587] vs 8.8% [384,338/4,371,664]; relative risk, 0.84 [95% confidence interval, 0.82-0.87]). Among exclusive cigarette users, those who completely switched to e-cigarettes during pregnancy also had a similar risk of small-for-gestational-age with nonusers (7.6% [259/3412] vs 8.8% [384,338/4,371,664]; relative risk, 0.83 [95% confidence interval, 0.73-0.93]). Among dual users before pregnancy, the risk of small-for-gestational-age decreased from 23.2% (7240/31,208) (relative risk, 2.53 [95% confidence interval, 2.47-2.58]) if continuing use to 16.9% (6617/39,142) (relative risk, 1.88 [95% confidence interval, 1.83-1.92]) if only quitting e-cigarettes or 15.1% (1254/8289) (relative risk, 1.61 [95% confidence interval, 1.52-1.70]) if only quitting cigarettes and further to 11.2% (7589/67,880) (relative risk, 1.23 [95% confidence interval, 1.20-1.25]) if both quitting e-cigarettes and cigarettes during pregnancy, compared with nonusers.

CONCLUSION

Among exclusive e-cigarette users, quitting e-cigarettes during pregnancy normalized the risk of small-for-gestational-age. Among exclusive cigarette users, quitting smoking or completely switching to e-cigarettes normalized small for gestational age risk. Among dual users, smoking cessation has a greater effect than quitting e-cigarettes only, although discontinuing the use of both may lead to the greatest reduction in the risk of small-for-gestational-age.

Maternal smoking status during pregnancy and low birth weight in offspring: systematic review and meta-analysis of 55 cohort studies published from 1986 to 2020

BACKGROUND

Maternal smoking during pregnancy may be associated with low birth weight (LBW) in offspring and global risk estimates have not been summarized previously. We aimed to systematically explore evidence regarding maternal smoking and the LBW risk in offspring globally and examine possible causes of heterogeneity across relevant studies.

METHODS

Comprehensive search of PubMed, Ovid Embase, Ovid Medline (R), and Web of science from inception until October 2021 was carried out. A random-effects meta-analysis was used to estimate the pooled odds ratio (OR) and corresponding 95% confidence interval (CI). Restricted cubic spline analysis with three knots was used to further examine the dose-response relationship.

RESULTS

Literature searches yielded 4940 articles, of which 53 met inclusion criteria (comprising 55 independent studies). Maternal smoking during pregnancy was significantly associated with the risk of LBW in offspring (OR = 1.89, 95% CI = 1.80-1.98). Furthermore, an obvious dose-response relationship between the amount of cigarettes daily smoked in pregnancy and the risk of LBW in offspring was observed. The results of subgroup analyses indicated that the risk of maternal smoking on LBW was larger in more recently conducted studies (P = 0.020) and longer period of active smoking during pregnancy (P = 0.002). No evidence of publication bias was found.

CONCLUSIONS

In summary, maternal smoking in pregnancy was significantly associated with a higher risk of LBW in offspring on a global scale. The risk of maternal smoking on infant LBW seems to be increasing over time, and was higher with longer smoking duration throughout pregnancy and more cigarettes smoked daily.

Risk of Gestational Diabetes Due to Maternal and Partner Smoking

Pregnant women are among the most vulnerable to environmental exposure to tobacco smoke (EET); which has been linked to problems in the mothers’ health; one of the most frequent is gestational diabetes (GD). For this reason, there are specific interventions and prevention strategies designed to reduce this exposure risk. However, currently, they are mostly aimed only at aiding the pregnant women with smoking cessation during pregnancy and do not assess or address the risk from passive exposure due to partner smoking. The aim of this work is to study the exposure to EET of pregnant women considering active and passive smoking and to evaluate its effect on the development of GD. This is an observational case-control study within a retrospective cohort of pregnant women. Information on smoking habits was obtained from both personal interviews and recorded medical history. In total, 16.2% of mothers and 28.3% of partners declared having been active smokers during pregnancy; 36.5% of the women presented EET during pregnancy when both active and passive smoking were considered. After adjustments, the association with the EET and GD of the mother was (aOR 1.10 95% CI: 0.64–1.92); for the EET of the partner, it was (aOR 1.66 95% CI: 1.01–2.77); for both partners, it was (aOR 1.82 95% CI: 1.15–2.89), adjusted by the mother’s age and body mass index. There is a lack of education regarding the effects of passive exposure to tobacco smoke. It is essential that pregnant women and their partners are educated on the risks of active and passive smoking; this could improve the effectiveness of other GD prevention strategies.

Substance Use During Pregnancy: A Comparative Review of Major Guidelines

Importance

Substance use during pregnancy is a major health issue for both the mother and the fetus, but it also represents an important public health concern.

Objective

The aim of this review was to summarize and compare recommendations from recently published guidelines on substance use during pregnancy and especially regarding alcohol, smoking, and drug use.

Evidence Acquisition

A descriptive review of guidelines from the Royal Australian and New Zealand College of Obstetricians and Gynaecologists, the World Health Organization (WHO), the Society of Obstetricians and Gynaecologists of Canada, and the American College of Obstetricians and Gynecologists on substance use was conducted. Regarding the term "substance use," the most recently published Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition substances were used.

Results

All the reviewed guidelines recommend appropriate counseling and screening women regarding alcohol, smoking, and drug use during the antenatal period, while the management options vary. More specifically, the prompt management of alcohol dependence is emphasized by all the guidelines except from the Royal Australian and New Zealand College of Obstetricians and Gynaecologists, which makes no recommendation upon. The use of alcohol during breastfeeding should be avoided. Regarding smoking cessation, all guidelines recommend the use of certain psychosocial, behavioral interventions, and pharmacotherapy. All the guidelines, except the one from the WHO, suggest screening drug users for coexistent sexually transmitted infections. Brief interventions are considered beneficial, while a gradual decrease in benzodiazepines is suggested, as well as the discontinuation of marijuana and methamphetamine use. However, there is controversy regarding breastfeeding in those women as the WHO recommends in favor, whereas the Society of Obstetricians and Gynaecologists of Canada and the American College of Obstetricians and Gynecologists recommend against this practice. Finally, all the guidelines state that, following delivery, close monitoring of the neonate is needed.

Conclusions

The diversity of guidelines' recommendations concerning substance use reflects the different ways of the management of pregnant women during routine antenatal care due to absence of strong evidence. More research in the areas of dispute may allow the adoption of an international consensus, in order to early detect and appropriately manage pregnant women with harmful addictions.

Impact of prenatal exposure characterization on early risk detection: Methodologic insights for the HEALthy Brain and Child Development (HBCD) study

BACKGROUND

A major challenge in prenatal drug exposure research concerns the balance of measurement quality with sample sizes necessary to address confounders. To inform the selection of optimal exposure measures for the HEALthy Brain and Child Development (HBCD) Study, we employed integrated analysis to determine how different methods used to characterize prenatal tobacco exposure influence the detection of exposure-related risk, as reflected in normal variations in birth weight.

METHODS

Participants were N = 2323 mother-infant dyads derived from 7 independent developmental cohorts harmonized on measures of exposure, outcome (birthweight), and covariates. We compared estimates of PTE-related effects on birthweight derived from linear regression models when PTE was categorized dichotomously based on any fetal exposure (30% exposed; 69% not exposed); versus categorically, based on common patterns of maternal smoking during pregnancy (never smoked 69%; quit smoking 16%; smoked intermittently 2%; smoked persistently 13%). We secondarily explored sex differences in PTE-birthweight associations across these categorization methods.

RESULTS

When PTE was categorized dichotomously, exposure was associated with a - 125-g difference in birthweight (95% C.I. -173.7 - -76.6, p < .0001). When PTE was characterized categorically based on maternal smoking patterns, however, exposure was associated with either no difference in birthweight if mothers quit smoking by the end of the first trimester (B = -30.6, 95% C.I. -88.7-27.4, p = .30); or a - 221.8 g difference in birthweight if mothers did not [95% C.I. (-161.7 to -282.0); p < .001]. Qualitative sex differences were also detected though PTE x sex interactions did not reach statistical significance. Maternal smoking cessation during pregnancy was associated with a 239.3 g increase in birthweight for male infants, and a 114.0 g increase in birthweight for females infants (p = .07).

CONCLUSIONS

Categorization of PTE based on patterns of maternal smoking rather than the presence or absence of exposure alone revealed striking nuances in estimates of exposure-related risk. The described method that captures both between-individual and within-individual variability in prenatal drug exposure is optimal and recommended for future developmental investigations such as the HBCD Study.

DNA methylome perturbations: an epigenetic basis for the emergingly heritable neurodevelopmental abnormalities associated with maternal smoking and maternal nicotine exposure†

Maternal smoking during pregnancy is associated with an ensemble of neurodevelopmental consequences in children and therefore constitutes a pressing public health concern. Adding to this burden, contemporary epidemiological and especially animal model research suggests that grandmaternal smoking is similarly associated with neurodevelopmental abnormalities in grandchildren, indicative of intergenerational transmission of the neurodevelopmental impacts of maternal smoking. Probing the mechanistic bases of neurodevelopmental anomalies in the children of maternal smokers and the intergenerational transmission thereof, emerging research intimates that epigenetic changes, namely DNA methylome perturbations, are key factors. Altogether, these findings warrant future research to fully elucidate the etiology of neurodevelopmental impairments in the children and grandchildren of maternal smokers and underscore the clear potential thereof to benefit public health by informing the development and implementation of preventative measures, prophylactics, and treatments. To this end, the present review aims to encapsulate the burgeoning evidence linking maternal smoking to intergenerational epigenetic inheritance of neurodevelopmental abnormalities, to identify the strengths and weaknesses thereof, and to highlight areas of emphasis for future human and animal model research therein.

Ancestral smoking and developmental outcomes: a review of publications from a population birth cohort†

The adverse effects on the child of maternal smoking in pregnancy is well-recognized, but little research has been carried out on the possible non-genetic effects of ancestral smoking prior to the pregnancy including parental initiation of cigarette smoking in their own childhoods or a grandmother smoking during pregnancy. Here, we summarize the studies that have been published mainly using data from the Avon Longitudinal Study of Parents and Children. We demonstrate evidence that ancestral smoking prior to or during pregnancy can often be beneficial for offspring health and both ancestor- and sex-specific. More specifically, we report evidence of (i) adverse effects of the father starting to smoke pre-puberty on his son's development; (ii) beneficial effects on the grandson if his maternal grandmother had smoked in pregnancy; and (iii) mainly adverse effects on the granddaughter when the paternal grandmother had smoked in pregnancy. The ancestor- and sex-specificity of these results are consistent with earlier studies reporting associations of health and mortality with ancestral food supply in their parents' and grandparents' pre-pubertal childhoods.

Associations between the exposure to organophosphate flame retardants during early pregnancy and the risk of spontaneous abortion based on metabolomics combined with tandem mass spectrometry

BACKGROUND

As potential substitutes for polybrominated diphenyl ethers (PBDEs), organophosphate flame retardants (OPFRs) have been frequently detected in the environment. They have been suggested to impair fetal growth and development in toxicological studies. However, there are few studies on their maternal effects before or during early pregnancy.

METHODS

This study was designed to investigate whether exposure to OPFRs before or during early pregnancy is associated with the risk of spontaneous abortion (SAB), using a nested case-control design based on the case data from clinical examinations in Shanghai, China. A total of 110 cases from this cohort project in 2019-2020 were included. The concentrations of OPFRs in maternal urine samples collected in early pregnancy were determined using Ultra high performance liquid chromatography- triple quadrupole mass spectrometer (UHPLC-MS/MS), and pregnancy outcomes were extracted from the medical records. Meanwhile, ultra high performance liquid chromatography time-of-flight mass spectrometer (UHPLC-Q-TOF/MS)-based metabonomics was used to obtain urine metabolic profiles of 110 women in early pregnancy.

RESULTS

According to the quantitative results, the content of bis(1-chloro-2-propyl)phosphate (BCIPP) in urine was significantly different between the SAB patients and the healthy pregnant women. Besides, metabolic profile analysis showed a significant difference in the urine metabolism profile in early pregnancy between SAB cases and controls. Twenty-five different metabolites were screened out, which showed different degrees of correlation with the urinary BCIPP concentration.

CONCLUSIONS

Based on these results, it suggests that there may be a certain correlation between BCIPP concentration in the urine and the risk of SAB from a metabolomics perspective, and its effect may be related to the metabolism of tryptophan and fatty acids.

Effects of Prenatal Exposure to Alcohol and Smoking on Fetal Heart Rate and Movement Regulation

Negative associations of prenatal tobacco and alcohol exposure (PTE and PAE) on birth outcomes and childhood development have been well documented, but less is known about underlying mechanisms. A possible pathway for the adverse fetal outcomes associated with PTE and PAE is the alteration of fetal autonomic nervous system development. This study assessed PTE and PAE effects on measures of fetal autonomic regulation, as quantified by heart rate (HR), heart rate variability (SD-HR), movement, and HR-movement coupling in a population of fetuses at ≥ 34 weeks gestational age. Participants are a subset of the Safe Passage Study, a prospective cohort study that enrolled pregnant women from clinical sites in Cape Town, South Africa, and the Northern Plains region, United States. PAE was defined by six levels: no alcohol, low quit early, high quit early, low continuous, moderate continuous, and high continuous; while PTE by 4 levels: no smoking, quit early, low continuous, and moderate/high continuous. Linear regression analyses of autonomic measures were employed controlling for fetal sex, gestational age at assessment, site, maternal education, household crowding, and depression. Analyses were also stratified by sleep state (1F and 2F) and site (South Africa, N = 4025, Northern Plains, N = 2466). The final sample included 6491 maternal-fetal-dyad assessed in the third trimester [35.21 ± 1.26 (mean ± SD) weeks gestation]. PTE was associated with a decrease in mean HR in state 2F, in a dose dependent fashion, only for fetuses of mothers who continued smoking after the first trimester. In state 1F, there was a significant increase in mean HR in fetuses whose mother quit during the first trimester. This effect was driven by the Norther Plains cohort. PTE was also associated with a significant reduction in fetal movement in the most highly exposed group. In South Africa a significant increase in mean HR both for the high quit early and the high continuous group was observed. In conclusion, this investigation addresses a critical knowledge gap regarding the relationship between PTE and PAE and fetal autonomic regulation. We believe these results can contribute to elucidating mechanisms underlying risk for adverse outcomes.

The effect of prenatal maternal physical activity and lifestyle in perinatal outcome: results from a Greek study

BACKGROUND

Several maternal characteristics, including lifestyle, have been associated with perinatal outcomes and birth anthropometric characteristics of the offspring. This study aimed to identify whether physical activity (PA) and other lifestyle parameters of the mother are associated with the pregnancy outcomes or with the infant's birth anthropometric characteristics.

METHODS

Participants were recruited in Mitera Maternity Hospital, Athens, Greece. Socio-demographic, medical history and anthropometric assessment took place. PA during pregnancy was assessed with the Pregnancy Physical Activity Questionnaire. Dietary assessment was conducted with the Food Frequency Questionnaire and adherence to the Mediterranean diet was evaluated with the MedDiet score. Birth weight and gestational age data were also collected.

RESULTS

Sedentary-intensity activity scores increased with increased educational level, while moderate-intensity activity scores decreased with increased educational level. Pregnant women who delivered large for gestational age infants had lower sports activity score. Higher vigorous and sports activity score was demonstrated in cases with a vaginal delivery compared with caesarean section. PA score was significantly and positively correlated with several nutrient intakes and PA was higher in women with a healthier nutritional pattern. Increased MedDiet scores were found in mothers with increased educational level.

CONCLUSIONS

Overall, PA was higher in women with a healthier nutritional pattern. An increased vs. a low activity level during pregnancy is positively associated with vaginal delivery and with the size of the offspring.

Maternal High Fat Diet Consumption Exaggerates Metabolic Disorders in Mice With Cigarette-Smoking Induced Intrauterine Undernutrition

Objectives: Maternal smoking causes fetal underdevelopment and results in births which are small for gestation age due to intrauterine undernutrition, leading to various metabolic disorders in adulthood. Furthermore, postnatal high fat diet (HFD) consumption is also a potent obesogenic factor, which can interact with maternal smoking. In this study, we aimed to determine whether maternal HFD consumption during pregnancy can reverse the adverse impact of maternal smoking and change the response to postnatal HFD consumption.

Methods: Female mice were exposed to cigarette smoke (SE, 2 cigarettes/day) or sham exposed for 5 weeks before mating, with half of the SE dams fed HFD (43% fat, SE+HFD). The same treatment continued throughout gestation and lactation. Male offspring from each maternal group were fed the same HFD or chow after weaning and sacrificed at 13 weeks.

Results: Maternal SE alone increased body weight and fat mass in HFD-fed offspring, while SE+HFD offspring showed the highest energy intake and glucose metabolic disorder in adulthood. In addition, postnatal HFD increased the body weight and aggravated the metabolic disorder caused by maternal SE and SE+HFD.

Conclusions: Maternal HFD consumption could not ameliorate the adverse effect of maternal SE but exaggerate metabolic disorders in adult offspring. Smoking cessation and a healthy diet are needed during pregnancy to optimize the health outcome in the offspring.

The effect of active and passive maternal smoking before and during pregnancy on neonatal weight at birth

INTRODUCTION

Smoking during pregnancy is a risk factor for adverse pregnancy outcomes. Data on the correlation between passive maternal smoking and pregnancy outcomes remain limited. We investigated the effect of active smoking and environmental tobacco smoke (ETS) during pregnancy on neonatal birthweight, including the risk for low birthweight (LBW).

MATERIAL AND METHODS

The study was conducted between 2010 and 2012. A group of 8625 women were surveyed during postpartum hospitalization. Outcome measures included mean birthweight of newborns. Additionally, odds ratios with confidence intervals were calculated to investigate the risk for LBW in active and passive smoking groups of mothers.

RESULTS

Lower birthweight (46 g - 307 g; p < 0.05) and a higher risk for LBW (OR = 1.35, 95% CI: 1.05-1.75; p < 0.05) were observed in all infants born to smoking mothers. A negative effect of ETS in pregnancy on the reduction of mean birthweight was also found. Additionally, we analyzed the cumulative effect of active and passive smoking on neonatal birthweight. A statistically significant reduction in neonatal weight at birth was found in a group of women who smoked actively and passively during pregnancy (130 g; p < 0.05).

CONCLUSIONS

Smoking is associated with decreased birthweight and in a group of active smoking mothers increased risk for LBW. This effect is dose-dependent and is also present in a group of women who smoked before pregnancy. There is also a cumulative effect of active smoking and ETS causing decreased neonatal birthweight and increased risk for low birthweight.

Smoking during Pregnancy and Adverse Birth and Maternal Outcomes in California, 2007 to 2016

OBJECTIVE

This study aimed to determine associations between maternal cigarette smoking and adverse birth and maternal outcomes.

STUDY DESIGN

This is a 10-year population-based retrospective cohort study including 4,971,896 resident births in California. Pregnancy outcomes of maternal smokers were compared with those of nonsmokers. The outcomes of women who stopped smoking before or during various stages of pregnancy were also investigated.

RESULTS

Infants of women who smoked during pregnancy were twice as likely to have low birth weight (LBW) and be small for gestational age (SGA), 57% more likely to have very LBW (VLBW) or be a preterm birth (PTB), and 59% more likely to have a very PTB compared with infants of nonsmokers. During the study period, a significant widening of gaps developed in both rates of LBW and PTB and the percentage of SGA between infants of maternal smokers and nonsmokers.

CONCLUSION

Smoking during pregnancy is associated with a significantly increased risk of adverse birth and maternal outcomes, and differences in rates of LBW, PTB, and SGA between infants of maternal smokers and nonsmokers increased during this period. Stopping smoking before pregnancy or even during the first trimester significantly decreased the infant risks of LBW, PTB, SGA, and the maternal risk for cesarean delivery.

The Effects of Different Smoking Patterns in Pregnancy on Perinatal Outcomes in the Southampton Women's Survey

Maternal smoking during pregnancy has established associations with poor perinatal outcomes. Among continuing pregnant smokers, harm-reduction strategies have been suggested, including temporary cessation of smoking during pregnancy, also known as partial quitting. Support for this strategy, however, remains limited. Six hundred and ninety-seven women in the Southampton Women's Survey who smoked at their last menstrual period were categorised into sustained quitters, partial quitters (quit in either the first or third trimester but not both) or sustained smokers (continued to smoke throughout pregnancy). In regression models, compared with infants born to sustained smokers, infants born to sustained quitters and partial quitters were heavier at birth by β = 0.64 standard deviations (SD) (WHO z-score) (95% CI: 0.47-0.80) and 0.48 SD (WHO z-score) (95% CI: 0.24-0.72) respectively, adjusted for confounders, with similar patterns seen for other anthropometric measures (head circumference and crown-heel length). Sustained quitters had longer gestations by β = 3.5 days (95% CI: 1.8-5.2) compared with sustained smokers, but no difference was seen for partial quitters. While sustained quitting remains the most desired outcome for pregnant smokers, partial quitting should be explored as a strategy to reduce some of the harmful effects of smoking on offspring in those who cannot achieve sustained quitting.

Determining a strategy to reduce smoking in pregnancy

BACKGROUND

Further efforts, informed by current data, are needed to reduce smoking during pregnancy.

AIMS

To describe trends in smoking during pregnancy and identify regions most likely to benefit from targeted smoking cessation interventions, in New South Wales (NSW), Australia.

MATERIALS AND METHODS

All women who gave birth in NSW between 1994 and 2016 were included. Smoking status was identified from the Perinatal Data Collection. For births between 2012 and 2016, women were grouped into Local Health District (LHD) of residence, and smoking rates calculated. The impacts of a hypothetical smoking cessation intervention in four LHDs with (i) high smoking rates and (ii) high numbers of smokers, were compared.

RESULTS

The overall smoking rate during pregnancy decreased from 22.1% in 1994 to 8.3% in 2016. [Correction added on 13 August 2020, after first online publication: the overall smoking rate during pregnancy in 1994 has been corrected from 14.5% to 22.1%.]. The decrease was lowest among women living in the most socioeconomically disadvantaged areas (41%) and highest among those living in the most advantaged areas (83%). Between 2012 and 2016, over half the women who smoked during pregnancy lived in one of four LHDs. Only 1% of women reporting smoking during pregnancy resided in the LHD with the highest smoking rate (34.7%). A simulated intervention targeting only four regions showed greater effect on the statewide smoking rate when targeting LHDs with high numbers of smokers rather than high smoking rates.

CONCLUSIONS

Despite decreases in rates of smoking during pregnancy, there was evidence of geographic clustering of smokers. The greatest reduction in overall smoking may come from interventions targeting the four LHDs with the highest number of smokers.

Association between maternal active smoking during pregnancy and placental weight: The Japan environment and Children's study

INTRODUCTION

Maternal smoking during pregnancy is a well-known risk factor for reduced birthweight. However, research investigating the association between maternal smoking and placental weight is scarce and inconsistent. Our study was conducted to evaluate the association between maternal smoking and placental weight and placental weight/birthweight ratio (PW/BW ratio).

METHODS

We used data from a birth cohort study, the Japan Environment and Children's Study (JECS). Main outcome measures were placental weight, PW/BW ratio, and the risk of high PW/BW ratio. High PW/BW ratio was defined as PW/BW ratio above the 90th percentile for gestational age and sex of offspring. The association between maternal smoking and placental weight was estimated as crude and as adjusted beta coefficients by applying linear regression analyses. Logistic regression analyses were also performed to estimate the association between maternal smoking and the risk of high PW/BW ratio.

RESULTS

Of the 91,951 pregnant women, the mean placental weight and the mean PW/BW ratio were lowest for the group of women who had never smoked. Smokers had higher odds ratio for high PW/BW ratio compared with non-smokers. Furthermore, among smokers, the mean placental weight and mean PW/BW ratio were lowest in women who smoked less than 5 daily cigarettes, and highest in women who smoked 20 or more daily cigarettes during pregnancy.

DISCUSSION

Placental weight was greater and PW/BW ratio was higher among smokers compared with non-smokers. Moreover, the number of daily cigarettes was positively associated with heavy placental weight.

A pilot study of the Tobacco Treatment Guidelines for High-Risk Groups (TOB-G) for pregnant and postpartum women

INTRODUCTION

Maternal smoking constitutes a significant risk to the fetus and is associated with multiple adverse pregnancy outcomes. Despite this, an estimated 6-19% of women in Europe smoke during pregnancy. We conducted a pilot study to examine the feasibility and effectiveness of the clinical practice recommendations of the 2017 Tobacco Cessation Guidelines for High-Risk Groups (TOB-G) for pregnant and postpartum women in an outpatient obstetrics setting.

METHODS

The guideline recommendations were tested on a sample of 67 pregnant women recruited from obstetrics outpatient visits. Pregnant women who smoked received three behavioural counselling sessions through a combination of face-toface and telephone consultations by a midwife trained in the TOBG tobacco treatment recommendations. Smoking status was assessed at 1 month and at 6 months follow-up via self-report.

RESULTS

Seventy-one per cent of pregnant smokers screened agreed to participate in the counselling intervention. Pregnant women participants (mean age, M=31.73 years, SD±6.09) smoked for an average of 12.2 (SD±6.55) years. Women reported smoking an average of 4.82 (SD±4.14) cigarettes per day with 51% reporting smoking within 30 minutes of waking, an indicator of higher levels of nicotine addiction. Rates of smoking abstinence among pregnant women undergoing the counselling intervention were 43.9% and 45.6% at the 1 month and at 6 months follow-up, respectively. Replacing those participants with missing data as smokers, the quit rates were 26.9% and 38.8% at the 1 month and 6 months follow-up, respectively.

CONCLUSIONS

The counselling intervention delivered to pregnant women who smoke was feasible to implement in a manner that was consistent with the TOB-G guideline recommendations in an outpatient obstetrics setting. Future work should focus on increasing uptake of evidence-based tobacco treatment recommendations in outpatient obstetrics settings.

Counselling for smoking cessation during pregnancy reduces tobacco-specific nitrosamine (NNAL) concentrations: A randomized controlled trial

INTRODUCTION

Smoking cessation during pregnancy is beneficial to both the mother and child. Our objective was to assess if an intensive smoking cessation intervention for pregnant women increases: a) rates of smoking cessation, and b) reduces exposure to tobacco-specific carcinogens during pregnancy.

METHODS

A two-group single-blinded parallel randomized controlled trial (RCT) was conducted involving 84 pregnant smokers in either a high intensity (n=42) or minimal contact control group (n=42). Women assigned to the high intensity smoking cessation intervention group received a single 30-minute behavioural counselling session and a tailored self-help booklet. The primary outcome measures were: 7-day point prevalence abstinence measured by selfreport and urine cotinine levels, and maternal tobacco specific carcinogens nitrosamine (NNAL) urine concentrations assessed at 32 weeks of gestation.

RESULTS

A significantly greater percentage of pregnant smokers quit smoking in the high intensity group compared to the low intensity control group (45.2% vs 21.4%; p=0.001). A significant decrease in urine cotinine concentrations was documented in the experimental group (-140.74 ± 361.70 ng/mL; p=0.004), with no significant decrease documented in the control group. A significant decrease in NNAL levels was also documented in the experimental group (158.17 ± 145.03 pg/mL before, 86.43 ± 112.54 pg/mL after; p=0.032) with no significant changes in the control group.

CONCLUSIONS

The high intensity intervention tested resulted in significantly greater cessation rates. Intensive smoking cessation interventions can be effective in reducing fetal exposure to NNAL. This is the first trial to report on NNAL tobacco-specific carcinogen concentrations before and after an intervention for smoking cessation during pregnancy.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01210118.

ABBREVIATIONS

5Αs: ask, advise, asses, assist, arrange; GHQ: general health questionnaire; ANOVA: analysis of variance; RCT: randomized control trials; NNAL: 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol.

Gender Difference in the Association between Environmental Tobacco Smoke and Birth Weight in Africa

The adverse health effects of exposure to environmental tobacco smoke (ETS) on children are well-documented, and yet, gender difference in low birthweight among newborns whose mothers were exposed to ETS during pregnancy still remains contentious. We therefore explored the association between ETS exposure and risk of low birthweight, and further determined the gender difference in the association between exposure to ETS during pregnancy and birth weight in Africa. The Demographic Health Surveys of 23 African countries with information on 208,027 newborns were used. The associations between exposure to ETS and birth weight was estimated using multiple logistic regression models. Exposure to ETS increased the risk of low birthweight in Africa (adjusted odds ratio (OR) = 1.06; 95% Confidence Interval (CI): 1.02–1.10). A stratified analysis, by gender, revealed that male newborns whose mothers were exposed to ETS were 1.08 (95% CI: 1.02–1.14) times more likely to be low in birthweight than those whose mothers were not exposed, with those exposed weekly (adjusted OR = 1.17; 95% CI: 1.01–1.35) and daily (adjusted OR = 1.06; 95% CI: 1.01–1.12) being more likely to have low birthweight. Exposure to ETS is significantly associated with low birthweight in Africa, mainly among male newborns. Gender could possibly be a modifier, and hence, research on biological plausibility is necessary. Moreover, a public health promotion on behavioral changes is likely to have a positive impact on newborns’ health.

Joint Effect of Maternal Tobacco Smoking and Pregestational Diabetes on Preterm Births and Congenital Anomalies: A Population-Based Study in Northern Italy

Smoking and pregestational diabetes (PGD) are recognized risk factors for adverse pregnancy outcomes, but to date, no population-based study has investigated their joint effects. Using hospital discharges, we identified all women with PGD delivering in Emilia-Romagna region during 2007-2010 matched 1 : 5 with parturients without diabetes. Our study endpoints were preterm births and congenital anomalies. We measured interaction between PGD and maternal smoking, by calculating excess prevalence and prevalence ratio due to interaction, relative excess risk due to interaction (RERI), attributable proportion (AP), and the synergy index (S). Analyses were performed in the overall study population and in the subgroup whose PGD was validated through diabetes registers. The study included 992 women with PGD (10.5% smokers) and 4788 comparison women (11.9% smokers). The effects of PGD and maternal tobacco smoking were greater than additive for both preterm birth (excess prevalence due to interaction = 11.7%, excess ratio due to interaction = 1.5, RERI = 2.39, AP = 0.51, S = 2.82) and congenital anomalies (excess prevalence due to interaction = 2.2%, excess ratio due to interaction = 1.3, RERI = 1.33, AP = 0.49, S = 5.03). Joint effect on both endpoints was confirmed in the subgroup whose PGD status was validated. In conclusion, we found that maternal tobacco smoking and PGD intensify each other's effect on preterm birth and congenital anomalies.

Maternal smoking during pregnancy and scholastic achievement in childhood: evidence from the LIFECOURSE cohort study

Background

Research on the impact of maternal smoking during pregnancy (MSDP) on scholastic achievement in the offspring has shown conflicting findings. The objective of this study was to assess the impact of MSDP on scholastic achievement in a birth cohort of children in 4th, 7th and 10th grades.

Methods

We analysed data from the LIFECOURSE study, a cohort study of risk and protective factors in all children born in Reykjavik, Iceland, in the year 2000 (N = 1151, girls = 49.3%). Retrospective registry data for 2014–2015 were merged with prospective survey data that were collected in April 2016. Data on MSDP were assessed during regular antenatal visits at the end of the first trimester. Standardized academic achievement scores were obtained from official school transcripts. Data were analysed using OLS regressions that were entered in three hierarchical blocks.

Results

Children of mothers who smoked tobacco during the first trimester consistently revealed between 5% and 7% lower scores on standardized academic achievement in 4th, 7th and 10th grade (∼6–8 points on a normally distributed 120 point scale) than those of mothers who had not smoked tobacco during this period (P < 0.05). These findings held after controlling for several factors associated with the time of birth (e.g. birth weight, maternal age at birth, birth order, parental cohabitation and household income), as well as the year of scholastic assessment (parental cohabitation, household income and parental education).

Conclusions

Maternal smoking during pregnancy was negatively related to scholastic achievement in the offspring during 4th, 7th and 10th grade.

Comparison of Online Survey Recruitment Platforms for Hard-to-Reach Pregnant Smoking Populations: Feasibility Study

Background

Recruiting hard-to-reach populations for health research is challenging. Web-based platforms offer one way to recruit specific samples for research purposes, but little is known about the feasibility of online recruitment and the representativeness and comparability of samples recruited through different Web-based platforms.

Objective

The objectives of this study were to determine the feasibility of recruiting a hard-to-reach population (pregnant smokers) using 4 different Web-based platforms and to compare participants recruited through each platform.

Methods

A screener and survey were distributed online through Qualtrics Panel, Soapbox Sample, Reddit, and Amazon Mechanical Turk (mTurk). Descriptive statistics were used to summarize results of each recruitment platform, including eligibility yield, quality yield, income, race, age, and gestational age.

Results

Of the 3847 participants screened for eligibility across all 4 Web-based platforms, 535 were eligible and 308 completed the survey. Amazon mTurk yielded the fewest completed responses (n=9), 100% (9/9) of which passed several quality metrics verifying pregnancy and smoking status. Qualtrics Panel yielded 14 completed responses, 86% (12/14) of which passed the quality screening. Soapbox Sample produced 107 completed surveys, 67% (72/107) of which were found to be quality responses. Advertising through Reddit produced the highest completion rate (n=178), but only 29.2% (52/178) of those surveys passed the quality metrics. We found significant differences in eligibility yield, quality yield, age, number of previous pregnancies, age of smoking initiation, current smokers, race, education, and income (P<.001).

Conclusions

Although each platform successfully recruited pregnant smokers, results varied in quality, cost, and percentage of complete responses. Moving forward, investigators should pay careful attention to the percentage yield and cost of online recruitment platforms to maximize internal and external validity.

Beliefs and advice-seeking behaviours for fertility and pregnancy: a cross-sectional study of a global sample

BACKGROUND

Pregnancy can motivate individuals to adopt lifestyle behaviours that protect the health of their offspring. The aims of the present study were to explore men's and women's beliefs about lifestyle, fertility and pregnancy, as well as where they seek advice.

METHODS

Participants (2185 women and 221 men, six unspecified) from 104 countries completed a questionnaire that explored their beliefs about what was important for a healthy pregnancy and their advice-seeking behaviours. Recruitment was via a Massive Open Online Course entitled 'Food as Medicine', with food, nutrient and health content. Comparisons of categorical data were performed using a chi-squared test (P = 0.05).

RESULTS

Eating a variety of fruits and vegetables and not smoking (both 93.7%) were the most frequently and equally ranked in the top-five factors for a healthy pregnancy. Taking prenatal supplements (26.8%) was considered to be less important. Participants in Westernised countries ranked not smoking or drinking alcohol as being significantly more important than those in other countries. Overall, doctors (47.7%) were the most common source of fertility and pregnancy advice. Larger proportions of those aged <40 years used the Internet (<40 years 44.1%, >40 years 18.2% χ² = 152.7, P < 0.01) and social media (<40 years 16.1%, >40 years 3.6%; χ² = 110.18, P < 0.01) for health information.

CONCLUSIONS

There is disconnection between beliefs and actions regarding the lifestyle behaviours considered to be important for a healthy pregnancy, particularly nutrition. Pregnancy advice-seeking has evolved, with younger men and women utilising the Internet and social media. Health professionals must consider new communication strategies to deliver evidence-based lifestyle advice, particularly for younger men and women and where access to healthcare is limited.

Changes in the smoking behavior of pregnant women andtheir family members during pregnancy: A cross-sectional study in China

INTRODUCTION

Studies regarding the changes in smoking behavior of pregnant women have been mostly conducted in high income countries but rarely in China. This study thus focused on investigating the changes in smoking behavior among pregnant women and their family members in China, both before and during pregnancy.

METHODS

A cross-sectional study was carried out at nine Women and Children’s Hospitals in Shanghai, China, in 2014. A total of 2831 gestational households were recruited. The chi-squared test, paired sample t-test and logistical regression analysis were used during statistical analysis.

RESULTS

The prevalence of smoking for all household members significantly declined during pregnancy: 76.2% of the pregnant women, 19.2% of their husbands and 14.0% of other family members quit smoking entirely. The average daily cigarette consumption rate decreased from 5.9 to 0.9 among pregnant women, 11.4 to 9.5 for husbands, and 11.4 to 9.5 for other family members (paired sample t-test, p<0.001). The likelihood that husbands continued smoking during pregnancy was significantly lower for those with a shorter history of smoking, had a lower daily cigarette consumption rate and a household registration in Shanghai.

CONCLUSIONS

The prevalence of smoking among pregnant women, husbands and other family members significantly declines during pregnancy. Thus, pregnancy is most likely a key period in which to provide families with health education regarding the effects of smoking, both during the pregnancy period and in general. Intervention programs designed to reduce smoking among husbands during pregnancy should focus on those with a long history of smoking, a high rate of daily cigarette consumption, and those with household registration not in Shanghai.

Associations between lifestyle factors and smoking status during pregnancy in a group of Romanian women

BACKGROUND

There is an estimated birth rate of 9.27 births/1,000 population in Romania each year, with approximately 8.4% born with low birth weight (LBW). Our purpose was to evaluate the relationships between maternal smoking and LBW and preterm birth in Mureș County, Romania.

METHODS

We conducted a cross-sectional survey of 1,278 mothers who had given birth in Mureș County obstetrical wards in 2015, based on a lifestyle questionnaire of 109 items and personal and laboratory data from hospitals records.

RESULTS

The variables associated with smoking during pregnancy taken into account were: Rroma ethnicity, education <8 grades, income lower than 140 dollars (minimum wages in our country), and lack of facilities in their households. In a multivariable model, smoking during pregnancy was correlated with a low level of education (p = .02), coffee and alcohol use (p = .0001), and lack of interest in potential environmental and behavioral risks during pregnancy (including smoking and diet). The newborn baby's weight was associated with smoker status of the mother (OR 1.71, 95%CI 1.09-2.66, p = .01), by the lack of ownership of a household (OR 3.52, 95%CI 2.27-5.47, p = .0001), and by the pregnant woman not receiving proper information regarding a healthy behavior and diet during pregnancy (OR 1.91, 95%CI 1.33-2.74, p = .0005).

CONCLUSION

Our study aimed to emphasize the high rates of maternal smoking during pregnancy and its importance in LBW outcomes in Romanian pregnant women. Moreover, the study highlights disparities in smoking status observed in ethnic minorities and those living in poverty.

Changes in first trimester fetal CYP1A1 and AHRR DNA methylation and mRNA expression in response to exposure to maternal cigarette smoking

Prenatal exposure to maternal cigarette smoking increases the risk of intrauterine growth retardation, adverse pregnancy outcomes, and diseases later in life. Exposure can result in postnatal global and gene-specific DNA methylation changes, with the latter well documented for the CYP1A1 and AHRR genes involved in the detoxification of xenobiotic substances. This study assessed the impact of exposure to maternal smoking on first trimester fetal CYP1A1 and AHRR mRNA expression and DNA methylation for CpG-sites displaying maternal smoking during pregnancy-mediated methylation changes at birth. The analyses included first trimester (6-12 weeks) placentas (N=39) and livers (N=43). For AHRR, exposure to maternal smoking was associated with increased DNA methylation in the placentas of female fetuses; mRNA expression, however, was unchanged. While exposure to maternal smoking was not associated with AHRR DNA methylation changes in fetal livers; mRNA expression was increased. For CYP1A1, exposure to maternal smoking was not associated with fetal DNA methylation changes whereas mRNA expression increased in placentas and male fetal livers. These results show that first trimester exposure to maternal smoking is associated with CYP1A1 and AHRR DNA methylation and mRNA expression changes. However, the results also indicate that maternal smoking during pregnancy-mediated postnatal CYP1A1 and AHRR DNA methylation changes are not imprinted during the first trimester.

Smoking in Pregnancy and Fetal Growth: The Case for More Intensive Assessment

Introduction

Many studies on prenatal tobacco exposure (PTE) effects have relied on single item retrospective measures of PTE. However, it is unclear how these single item measures may relate to more intensive maternal self-reports and to biological markers of maternal use and/or fetal exposure. It is also unclear whether these measures may be more valid predictors of fetal growth (gestational age, birthweight, head circumference, and birth length).

Methods

Data were obtained from 258 women during their pregnancy. PTE was assessed by four methods: a single item question, a calendar-based self-report measure from each trimester of pregnancy, maternal salivary cotinine assays, and nicotine and metabolites in infant meconium. We hypothesized that the more intensive measures and biological assays would account for additional variance in birth outcomes, above and beyond the single item measure.

Results

The single item self-report measure was not related to fetal growth. However, the more intensive calendar based self-report measure and the biological assays of PTE (ie, maternal salivary assays and infant meconium) were significant predictors of poor fetal growth, even with the single item measure in the model.

Conclusions

The negative effects of PTE on important child outcomes may be greatly underestimated in the literature as many studies use single item self-report measures to ascertain PTE. Whereas more intensive self-report measures or biological assays may be cost prohibitive in large scale epidemiological studies, using a combination of measures when possible should be considered given their superiority both identifying prenatal smokers and predicting poor fetal growth.

Implications

The present work underscores the importance of measurement issues when assessing associations between PTE and fetal growth. Results suggest that we may be greatly underestimating the negative effects of prenatal smoking on fetal growth and other important child outcomes if we rely solely on restricted single item self-report measures of prenatal smoking. Researchers should consider more intensive prospective self-report measures and biological assays as viable and superior alternatives to single item self-report measures.

Effect of Smoking Behavior before and during Pregnancy on Selected Birth Outcomes among Singleton Full-Term Pregnancy: A Murmansk County Birth Registry Study

The aim of our study was to assess associations between smoking behavior before and during pregnancy and selected adverse birth outcomes. This study is based on the Murmansk County Birth Registry (MCBR). Our study includes women who delivered a singleton pregnancy after 37 weeks of gestation (N = 44,486). Smoking information was self-reported and assessed at the first antenatal visit during pregnancy. We adjusted for potential confounders using logistic regression. The highest proportion of infants with low values of birth weight, birth length, head circumference, ponderal index and of the Apgar score at 5 min was observed for women who smoked both before and during pregnancy. We observed a dose-response relationship between the number of cigarettes smoked per day during pregnancy and the odds of the aforementioned adverse birth outcomes; neither were there significant differences in their occurrences among non-smokers and those who smoked before but not during pregnancy. Moreover, smoking reduction during pregnancy relative to its pre-gestation level did not influence the odds of the adverse birth outcomes. Our findings emphasize a continued need for action against tobacco smoking during pregnancy.

Differences in dietary and lifestyle habits between pregnant women with small fetuses and appropriate-for-gestational-age fetuses

AIM

The purpose of this study was to determine differences in lifestyle and dietary habits between pregnant women with small for gestational age (SGA) fetuses and those appropriate for gestational age (AGA).

METHODS

This cross-sectional, prospective study was conducted over 14 months and included 46 mothers with SGA and 81 with AGA fetuses. Fetal growth was assessed by a routine third trimester scan. Participants completed questionnaires regarding dietary habits, lifestyle behavior and sociodemographic characteristics during the third trimester.

RESULTS

Mothers maintaining a Mediterranean-type diet and lifestyle were more likely to have an AGA fetus (P < 0.05). The same number of women in both groups ate a vegetarian diet. Women in the SGA group had a lower intake of certain micronutrients: carotene, folic acid, iron, potassium and magnesium (P < 0.05). Women in the AGA group ate more vegetables, especially green beans, carrots, lettuce and oranges (P < 0.05). Bread, pasta, cakes and jam were also more frequently consumed by the AGA group (P < 0.05). Mothers in the SGA group drank more cola (P < 0.05), while mothers in the AGA group drank more diet cola and wine (P < 0.05). Women in the SGA group smoked more cigarettes per day (P < 0.05).

CONCLUSIONS

Mothers of SGA fetuses had a different nutritional intake and cigarette smoking habits compared with mothers of AGA fetuses. No other differentiating lifestyle habits were observed between the groups. Thus, intrauterine growth conditions might be improved by the endorsement of certain dietary habits during pregnancy.

Somatic growth in the first six months of life of infants exposed to maternal smoking in pregnancy

Background

Some studies suggest a relationship between maternal smoking during pregnancy and not only intrauterine fetal growth restriction or low birth weight, but also with changes in the postnatal growth and development. The objective of the present study was to investigate the effects of smoking during pregnancy on infants growth in the first 6 months of life compared with a control group and a group with idiopathic intrauterine growth restriction.

Methods

Longitudinal observational study using a convenience sample of newborns divided into three groups: infants of smoking mothers (tobacco), with idiopathic intrauterine growth restriction (IUGR) and a control group. The sample was selected from two hospitals in Porto Alegre, located in southern Brazil, between 2011 and 2015. Newborns were evaluated at birth, 7 and 15 days, and in the first, third, and sixth month. Anthropometric measures were weight, length and head circumference. The growth indicators used were expressed as z-scores. The analyses were performed using the generalized estimating equation method.

Results

The sample included 273 mother/newborn pairs: 86 tobacco group, 34 IUGR group, and 153 control group. In terms of weight at birth, all groups differed significantly (p < 0.001). The birth length of tobacco and control groups were similar, but the IUGR group was lower than both (p < 0.001). We found no differences in growth trajectory between tobacco and control group, but there were differences in the growth of the IUGR group when compared with the other groups. At 6 months of age, all groups had similar anthropometric measurements.

Conclusion

Intrauterine growth restriction had major impact on the growth trajectory of the infants studied, regardless of other factors, such as smoking and diet.

Evaluation of a complex healthcare intervention to increase smoking cessation in pregnant women: interrupted time series analysis with economic evaluation

Objectives

To evaluate the effectiveness of a complex intervention to improve referral and treatment of pregnant smokers in routine practice, and to assess the incremental costs to the National Health Service (NHS) per additional woman quitting smoking.

Design

Interrupted time series analysis of routine data before and after introducing the intervention, within-study economic evaluation.

Setting

Eight acute NHS hospital trusts and 12 local authority areas in North East England.

Participants

37 726 records of singleton delivery including 10 594 to mothers classified as smoking during pregnancy.

Interventions

A package of measures implemented in trusts and smoking cessation services, aimed at increasing the proportion of pregnant smokers quitting during pregnancy, comprising skills training for healthcare and smoking cessation staff; universal carbon monoxide monitoring with routine opt-out referral for smoking cessation support; provision of carbon monoxide monitors and supporting materials; and an explicit referral pathway and follow-up protocol.

Main outcome measures

Referrals to smoking cessation services; probability of quitting smoking during pregnancy; additional costs to health services; incremental cost per additional woman quitting.

Results

After introduction of the intervention, the referral rate increased more than twofold (incidence rate ratio=2.47, 95% CI 2.16 to 2.81) and the probability of quitting by delivery increased (adjusted OR=1.81, 95% CI 1.54 to 2.12). The additional cost per delivery was £31 and the incremental cost per additional quit was £952; 31 pregnant women needed to be treated for each additional quitter.

Conclusions

The implementation of a system-wide complex healthcare intervention was associated with significant increase in rates of quitting by delivery.

Psychosocial interventions for supporting women to stop smoking in pregnancy

BACKGROUND

Tobacco smoking remains one of the few preventable factors associated with complications in pregnancy, and has serious long-term implications for women and babies. Smoking in pregnancy is decreasing in high-income countries, but is strongly associated with poverty and is increasing in low- to middle-income countries.

OBJECTIVES

To assess the effects of smoking cessation interventions during pregnancy on smoking behaviour and perinatal health outcomes.

SEARCH METHODS

In this sixth update, we searched the Cochrane Pregnancy and Childbirth Group's Trials Register (13 November 2015), checked reference lists of retrieved studies and contacted trial authors.

SELECTION CRITERIA

Randomised controlled trials, cluster-randomised trials, and quasi-randomised controlled trials of psychosocial smoking cessation interventions during pregnancy.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and trial quality, and extracted data. Direct comparisons were conducted in RevMan, with meta-regression conducted in STATA 14.

MAIN RESULTS

The overall quality of evidence was moderate to high, with reductions in confidence due to imprecision and heterogeneity for some outcomes. One hundred and two trials with 120 intervention arms (studies) were included, with 88 trials (involving over 28,000 women) providing data on smoking abstinence in late pregnancy. Interventions were categorised as counselling, health education, feedback, incentives, social support, exercise and dissemination.In separate comparisons, there is high-quality evidence that counselling increased smoking cessation in late pregnancy compared with usual care (30 studies; average risk ratio (RR) 1.44, 95% confidence interval (CI) 1.19 to 1.73) and less intensive interventions (18 studies; average RR 1.25, 95% CI 1.07 to 1.47). There was uncertainty whether counselling increased the chance of smoking cessation when provided as one component of a broader maternal health intervention or comparing one type of counselling with another. In studies comparing counselling and usual care (largest comparison), it was unclear whether interventions prevented smoking relapse among women who had stopped smoking spontaneously in early pregnancy. However, a clear effect was seen in smoking abstinence at zero to five months postpartum (11 studies; average RR 1.59, 95% CI 1.26 to 2.01) and 12 to 17 months (two studies, average RR 2.20, 95% CI 1.23 to 3.96), with a borderline effect at six to 11 months (six studies; average RR 1.33, 95% CI 1.00 to 1.77). In other comparisons, the effect was unclear for most secondary outcomes, but sample sizes were small.Evidence suggests a borderline effect of health education compared with usual care (five studies; average RR 1.59, 95% CI 0.99 to 2.55), but the quality was downgraded to moderate as the effect was unclear when compared with less intensive interventions (four studies; average RR 1.20, 95% CI 0.85 to 1.70), alternative interventions (one study; RR 1.88, 95% CI 0.19 to 18.60), or when smoking cessation health education was provided as one component of a broader maternal health intervention.There was evidence feedback increased smoking cessation when compared with usual care and provided in conjunction with other strategies, such as counselling (average RR 4.39, 95% CI 1.89 to 10.21), but the confidence in the quality of evidence was downgraded to moderate as this was based on only two studies and the effect was uncertain when feedback was compared to less intensive interventions (three studies; average RR 1.29, 95% CI 0.75 to 2.20).High-quality evidence suggests incentive-based interventions are effective when compared with an alternative (non-contingent incentive) intervention (four studies; RR 2.36, 95% CI 1.36 to 4.09). However pooled effects were not calculable for comparisons with usual care or less intensive interventions (substantial heterogeneity, I2 = 93%).High-quality evidence suggests the effect is unclear in social support interventions provided by peers (six studies; average RR 1.42, 95% CI 0.98 to 2.07), in a single trial of support provided by partners, or when social support for smoking cessation was provided as part of a broader intervention to improve maternal health.The effect was unclear in single interventions of exercise compared to usual care (RR 1.20, 95% CI 0.72 to 2.01) and dissemination of counselling (RR 1.63, 95% CI 0.62 to 4.32).Importantly, high-quality evidence from pooled results demonstrated that women who received psychosocial interventions had a 17% reduction in infants born with low birthweight, a significantly higher mean birthweight (mean difference (MD) 55.60 g, 95% CI 29.82 to 81.38 g higher) and a 22% reduction in neonatal intensive care admissions. However the difference in preterm births and stillbirths was unclear. There did not appear to be adverse psychological effects from the interventions.The intensity of support women received in both the intervention and comparison groups has increased over time, with higher-intensity interventions more likely to have higher-intensity comparisons, potentially explaining why no clear differences were seen with increasing intervention intensity in meta-regression analyses. Among meta-regression analyses: studies classified as having 'unclear' implementation and unequal baseline characteristics were less effective than other studies. There was no clear difference between trials implemented by researchers (efficacy studies), and those implemented by routine pregnancy staff (effectiveness studies), however there was uncertainty in the effectiveness of counselling in four dissemination trials where the focus on the intervention was at an organisational level. The pooled effects were similar in interventions provided for women classified as having predominantly low socio-economic status, compared to other women. The effect was significant in interventions among women from ethnic minority groups; however not among indigenous women. There were similar effect sizes in trials with biochemically validated smoking abstinence and those with self-reported abstinence. It was unclear whether incorporating use of self-help manuals or telephone support increased the effectiveness of interventions.

AUTHORS' CONCLUSIONS

Psychosocial interventions to support women to stop smoking in pregnancy can increase the proportion of women who stop smoking in late pregnancy and the proportion of infants born low birthweight. Counselling, feedback and incentives appear to be effective, however the characteristics and context of the interventions should be carefully considered. The effect of health education and social support is less clear. New trials have been published during the preparation of this review and will be included in the next update.

Tobacco consumption and spontaneous quitting at the first trimester of pregnancy

INTRODUCTION

The purpose of this study was to examine the association between pregnant women's socio-demographic characteristics, smoking-related variables and psychological symptoms (anxiety and depression) and both tobacco consumption and spontaneous quitting at the first trimester of pregnancy. In particular, we wished to examine the contribution of depressive symptoms to tobacco consumption and spontaneous quitting, while controlling for anxiety symptoms, socio-demographic and smoking-related variables.

METHODS

The sample was comprised of 901 Spanish pregnant women. Assessment included an ad hoc questionnaire with socio-demographic and tobacco consumption information, the Edinburg Postnatal Depression Scale (EPDS), and The State-Anxiety Inventory (STAI-S). Two multiple logistic regression analyses were performed, respectively to predict tobacco consumption and to predict spontaneous quitting.

RESULTS

Having a partner who smokes (OR=5.578), not having a college education (OR=2.803), higher scores on the EPDS (OR=1.073) and higher scores on the STAI-S (OR=1.027) increase the probability of continuing smoking. Being primiparous (OR=2.463), having a college education (OR=2.141), smoking fewer cigarettes before pregnancy (OR=1.175), and lower scores on the STAI-S (OR=1.045) increase the probability of spontaneously quitting smoking at the first trimester of pregnancy.

CONCLUSIONS

Depressive symptoms were a predictor of tobacco consumption but not of spontaneous quitting; spontaneous quitting was better predicted by anxiety symptoms. These findings support recommendations that women with depressive symptoms are at risk for smoking during pregnancy and highlight that anxious symptoms should be targeted in interventions for smoking cessation during pregnancy.

Use of human milk in the assessment of toxic metal exposure and essential element status in breastfeeding women and their infants in coastal Croatia

Pregnant and lactating women and infants are vulnerable population groups for adverse effects of toxic metals due to their high nutritional needs and the resultant increased gastrointestinal absorption of both, essential and toxic elements. Although breastfeeding is recommended for infants worldwide, as human milk is the best source of nutrients and other required bioactive factors, it is also a pathway of maternal excretion of toxic substances including toxic metals and thus a source of infant exposure. The aim of this research was to assess health risks in breastfeeding women in the coastal area of the Republic of Croatia and their infants (N=107) due to maternal exposure to Cd and Pb via cigarette smoking, and Hg via seafood and dental amalgam fillings, and their interaction with essential elements. Biological markers of exposure were the concentrations of main toxic metals Pb, Cd and Hg in maternal blood and three types of breast milk throughout lactation stages. Biological markers of effects were the levels of essential elements Ca, Fe, Cu, Zn and Se in maternal serum and breast milk. With regard to cigarette smoking as a source of exposure to Cd and Pb, there were effects of smoking on Cd concentration in blood and correlations between the smoking index and Cd concentrations in maternal blood (ρ=0.593; P<0.001) and mature milk (ρ=0.271; P=0.011) and Pb concentration in transitional milk (ρ=0.280; P=0.042). Regarding fish, we found correlations between weekly consumption frequency and total Hg concentrations in maternal blood (ρ=0.292; P=0.003) and mature milk (ρ=0.303; P=0.003). The number of dental amalgam fillings correlated with total Hg concentrations in colostrum (ρ=0.489; P=0.005) and transitional milk (ρ=0.309; P=0.018). As for the essential element status, only Se levels in maternal serum decreased by 10% in persons who continued smoking during pregnancy compared to non-smokers. In conclusion, the levels of main toxic metals Cd, Pb and Hg and essential elements Ca, Fe, Cu, Zn and Se in maternal blood and three types of breast milk samples in the studied area of coastal Croatia showed no risk of disrupted essential element levels with regard of toxic metal exposure in both breastfeeding women and their infants.

Assessment of global DNA methylation in the first trimester fetal tissues exposed to maternal cigarette smoking

AIMS

Maternal cigarette smoking during pregnancy increases the risk of negative health consequences for the exposed child. Epigenetic mechanisms constitute a likely link between the prenatal exposure to maternal cigarette smoking and the increased risk in later life for diverse pathologies. Maternal smoking induces gene-specific DNA methylation alterations as well as global DNA hypermethylation in the term placentas and hypomethylation in the cord blood. Early pregnancy represents a developmental time where the fetal epigenome is remodeled and accordingly can be expected to be highly prone to exposures with an epigenetic impact. We have assessed the influence of maternal cigarette smoking during the first trimester for fetal global DNA methylation.

METHODS AND RESULTS

We analyzed the human fetal intestines and livers as well as the placentas from the first trimester pregnancies. Global DNA methylation levels were quantified with ELISA using a methylcytosine antibody as well as with the bisulfite pyrosequencing of surrogate markers for global methylation status, LINE-1, and AluYb8. We identified gender-specific differences in global DNA methylation levels, but no significant DNA methylation changes in exposure responses to the first trimester maternal cigarette smoking.

CONCLUSIONS

Acknowledging that only examining subsets of global DNA methylation markers and fetal sample availability represents possible limitations for the analyses, our presented results indicate that the first trimester maternal cigarette smoking is not manifested in immediate aberrations of fetal global DNA methylation.

Smoke-free legislation and child health

In this paper, we aim to present an overview of the scientific literature on the link between smoke-free legislation and early-life health outcomes. Exposure to second-hand smoke is responsible for an estimated 166 ,000 child deaths each year worldwide. To protect people from tobacco smoke, the World Health Organization recommends the implementation of comprehensive smoke-free legislation that prohibits smoking in all public indoor spaces, including workplaces, bars and restaurants. The implementation of such legislation has been found to reduce tobacco smoke exposure, encourage people to quit smoking and improve adult health outcomes. There is an increasing body of evidence that shows that children also experience health benefits after implementation of smoke-free legislation. In addition to protecting children from tobacco smoke in public, the link between smoke-free legislation and improved child health is likely to be mediated via a decline in smoking during pregnancy and reduced exposure in the home environment. Recent studies have found that the implementation of smoke-free legislation is associated with a substantial decrease in the number of perinatal deaths, preterm births and hospital attendance for respiratory tract infections and asthma in children, although such benefits are not found in each study. With over 80% of the world’s population currently unprotected by comprehensive smoke-free laws, protecting (unborn) children from the adverse impact of tobacco smoking and SHS exposure holds great potential to benefit public health and should therefore be a key priority for policymakers and health workers alike.

Mechanistic Evaluation of Benzo[a]pyrene's Developmental Toxicities Mediated by Reduced Cyp19a1b Activity

Benzo[a]pyrene (BaP) is a ubiquitous environmental contaminant that is both an endocrine disruptor and a carcinogen. Aromatase (CYP19) is a key enzyme in steroidogenesis that is responsible for conversion of androgens to estrogens and thus plays a key role in steroid homeostasis. We hypothesized that some of the adverse outcomes of early developmental exposure to BaP are the result of reduced Cyp19a1b activity. Our goal was to investigate the role of estrogen homeostasis during early development and determine the role of aromatase inhibition as a relevant mechanism in BaP's developmental toxicities. One-cell zebrafish embryos were injected with a Cyp19a1b-morpholino (MO) or control-MO. Other non-injected embryos were exposed to waterborne BaP, fadrozole (a Cyp19 inhibitor), estradiol (E2), BaP + E2, Cyp19a1b MO + E2, or fadrozole + E2 for 96 hours post-fertilization (hpf). Adverse outcomes were compared between treatments, and the ability of E2 co-exposure to rescue each observed dysmorphology was assessed. BaP significantly decreased cyp19a1b gene expression in 96 hpf zebrafish larvae homogenates. Concentrations of E2 in 48 hpf larvae were significantly decreased by BaP, fadrozole and Cyp19a1b-MO. Cumulative mortality of zebrafish larvae was significantly increased following BaP or fadrozole exposure or Cyp19a1b knockdown compared to controls. E2 co-treatment rescued mortality caused by 10 μg/L BaP, 10 μg/L fadrozole, or Cyp19a1b-MO. In a treatment-blinded morphological assessment of larvae at 96 hpf, several phenotypes were negatively impacted by BaP, fadrozole, or Cyp19a1b knockdown and rescued by exogenous E2 co-treatment; these included body length, optic vesicle size, swim bladder inflation, pericardial and abdominal edema, and incidence of normal larval tail shape. Abnormal pectoral fins were caused by BaP exposure only. Uninflated swim bladders were caused by all treatments including E2 alone. Our results indicate that certain BaP-mediated adverse developmental outcomes were mechanistically in accordance with BaP-mediated Cyp19a1b inhibition.

Nicotine and Tobacco Use Prevention among Youth and Families

OBJECTIVE

To review the importance of and evidence-based strategies to prevent tobacco use and promote tobacco cessation in the pediatric setting.

DATA SOURCES

Literature review of evidence-based resources on tobacco use and prevention/cessation interventions in the pediatric/adolescent population.

CONCLUSION

Knowledge of the impact of tobacco use on cancer risk, second- and third-hand smoke carcinogenesis, and newer methods of tobacco delivery is necessary to select appropriate and effective prevention and cessation strategies.

IMPLICATIONS FOR NURSING PRACTICE

Systematic evaluation of both parents and children for tobacco use can identify patients that will benefit from tobacco cessation interventions. Patients and families need education and support so they can make good decisions and adhere to recommendations for prevention and cessation of tobacco use.

Social Disparities in Maternal Smoking during Pregnancy: Comparison of Two Birth Cohorts (1996-2002 and 2003-2012) Based on Data from the German KiGGS Study

Background: Maternal smoking during pregnancy represents a significant developmental risk for the unborn child. This study investigated social differences in maternal smoking behavior during pregnancy in mothers living in Germany. The study focused on maternal age at delivery, social status and migration background. Method: The evaluation of data was based on two surveys carried out as part of the German Health Interview and Examination Survey for Children and Adolescents (KiGGS) carried out in 2003-2006 and in 2009-2012. The study compared the information given by parents of children aged between 0 and 6 years who were born either in the period from 1996 to  2002 (KiGGS baseline study, n = 4818) or in the period from 2003 to 2012 (KiGGS Wave 1, n = 4434). Determination of social status was based on parental educational levels, occupational position and income. Children classified as having a two-sided migration background either had parents, both of whom had immigrated to Germany, or were born abroad and had one parent who had immigrated to Germany; children classified as having a one-sided migration background had been born in Germany but had one parent who had immigrated to Germany. Results: The percentage of children whose mothers had smoked during pregnancy was 19.9 % for the older birth cohort and 12.1 % for the younger birth cohort. In both birth cohorts, the probability of being exposed to tobacco smoke was twice as high for children whose mothers were aged < 25 years at delivery compared to the children of older mothers. Children from socially deprived families were most affected by smoking behavior, and the relative social differences were found to have even increased over time (KiGGS baseline study: OR = 6.34; 95 % CI = 4.53-8.86; KiGGS Wave 1: OR = 13.88; 95 % CI = 6.85-28.13). A two-sided migration background was associated with a lower risk of exposure to smoking. Conclusions: The KiGGS results are in accordance with the results of other national and international studies which have shown that the percentage of mothers who smoke during pregnancy is declining. Because of a change in the method how data are collected for the KiGGS survey (written questionnaire vs. telephone interview) the trend results must be interpreted with caution. Measures aimed at preventing smoking and weaning women off smoking should focus particularly on younger and socially deprived mothers.

Exposure to active and passive smoking among Greek pregnant women

Background

Active smoking and exposure to passive smoke are responsible for numerous adverse pregnancy outcomes for women and their infants. The aim of this study was to explore the perceptions, attitudes, patterns of personal tobacco use and exposure to environmental smoke among a sample of pregnant women in Greece.

Method

A cross sectional survey was undertaken of 300 women identified from the perinatal care records of the Maternity Departments of two hospitals in Athens between February 2013 and May 2013. Data on active and passive maternal smoking status in the first, second, and third trimesters of pregnancy, fetal and neonatal tobacco related complications, exposure to environmental tobacco smoke during pregnancy, quit attempts, behaviors towards avoiding passive smoking and beliefs towards smoking cessation during pregnancy were collected using self-administered questionnaires on the 3rd postnatal day. Women also completed the Edinburgh Postnatal Depression Scale (EPDS).

Results

Of 300 women recruited to the study 48 % reported tobacco use during the first trimester of pregnancy. Amongst participants who were tobacco users, 83.3 % reported making an attempt to quit but less than half (45.1 %) were successful. Among women who continued to smoke during pregnancy the majority (55.8 %) reported that they felt unable to quit, and 9.3 % reported that they considered smoking cessation was not an important health issue for them. Participants who continued to smoke during pregnancy were more likely to report fetal (χ2 = 11.41; df = 5; p < 0.05) and newborn complications (χ2 = 6.41; df = 2; p < 0.05), including preterm birth and low birth weight. Participants who reported that their partners were smokers were more likely to smoke throughout their pregnancy (χ2 = 14.62; df = 1; p < 0.001). High rates of second-hand smoke exposure were reported among both smoking and non-smoking women. Pregnant smokers had significantly higher levels of postnatal depressive and anxiety symptomatology, as measured using the EPDS, than non-smokers.

Conclusion

Our data supports the importance of ensuring that pregnant women, their partners and close relatives are educated on the health risks of active and passive smoking and how these could have an adverse effect to their fetus and infants, as well as the pregnant women themselves.

Association Between Maternal Smoking During Pregnancy and Birth Weight: An Appropriately Adjusted Model From the Japan Environment and Children's Study

Background

There has been no large nationwide population-based study to examine the effects of maternal smoking status during pregnancy on birth weight that simultaneously controlled for clinical information, socioeconomic status, and maternal weight. Thus, this study aimed to determine the association between maternal smoking status during pregnancy and birth weight, while taking these confounding factors into consideration.

Methods

This study examined the first-year fixed dataset from a large nationwide birth cohort study that commenced in 2011. The dataset consisted of information on 9369 singleton infants born before December 31, 2011. Children were divided into 4 groups for statistical analysis: those born to mothers who did not smoke (NS), who quit smoking before pregnancy, who quit smoking during early pregnancy, and who smoked (SM). Multiple linear regression models were conducted for each sex to examine the association between maternal smoking status during early pregnancy and fetal growth. Birth weight was estimated using the least-squares method after controlling for covariates.

Results

After controlling for potential confounding factors, maternal smoking status during pregnancy was significantly associated with birth weight. There was a significant difference in birth weight between NS and SM for both male and female infants (male infants, 3096.2 g [NS] vs 2959.8 g [SM], P < 0.001; female infants, 3018.2 g [NS] vs 2893.7 g [SM], P < 0.001).

Conclusions

Using data from a large nationwide birth cohort study in Japan, we have shown that maternal smoking during pregnancy may reduce birth weight by 125–136 g.