Prenatal weight gain patterns and infant birthweight associated with maternal smoking

Biochemically confirmed smoking cessation and gestational weight gain

BACKGROUND

Prenatal smoking cessation has substantial health benefits for mothers and offspring, but concerns about weight gain may be a barrier to quitting. We quantified gestational weight gain associated with biochemically confirmed smoking cessation.

METHODS

Data originated from a randomized controlled cessation trial: Smoking Cessation in Pregnancy project (1987-1991). We calculated gestational weight gain using self-reported prepregnancy weight and measured weight at 30-34 weeks of gestation. We used linear regression to estimate adjusted mean differences in gain for quitters versus continuing smokers by the last trimester. The effects of quitting earlier (by 2nd trimester) versus later (by 3rd trimester) were calculated. We assessed the percentages who gained weight according to Institute of Medicine (IOM) recommendations within 2 weeks of a full-term delivery.

RESULTS

At 30-34 weeks, nulliparous and multiparous quitters gained an average of 3.0 pounds (95% CI 0.9-5.1 pounds) (1.4 kg [0.4-2.3 kg]) and 6.6 pounds (95% CI 4.3-8.9 pounds) (3.0 kg [1.9-4.0 kg]) more, respectively, than continuing smokers. Weight gain in early quitters did not differ significantly from that in late quitters. Quitters were more likely than continuing smokers to gain above current guidelines (60.3% vs 46.3%) and were less likely to gain below guidelines (11.5% vs 21.6%) (P = 0.002).

CONCLUSIONS

Although quitters had modest additional weight gain by 30-34 weeks compared to continuing smokers, a high proportion in both groups gained in excess of IOM recommendations. Both quitters and continuing smokers may need support to achieve optimal gestational weight gain.

Appetite during the second and third trimesters mediates the impact of prenatal environmental tobacco smoke exposure on symmetric full-term low birth weight

Objective: To examine the relationship of prenatal environmental tobacco smoke (ETS) exposure and full-term low birth weight (FT-LBW) when taking anthropometric proportionality into consideration, and explore whether appetite mediates their association.Study design: We conducted a case-control study among pregnant women at two Women and Children's Hospitals in Guangdong, China. Information was collected through interview and medical records review. A series of logistic and linear regressions were used to examine the relationships of prenatal ETS exposure, appetite, and FT-LBW.Results: After adjusting for the potential confounders, prenatal ETS exposure was significantly negatively associated with FT-LBW (OR: 1.83, 95%CI: 1.35-2.48) and negatively correlated with maternal appetite in second and third trimester during pregnancy (β: -0.11, standard error: 0.03). Moreover, mediation analysis illustrated that maternal appetite partially mediated 12.00% of their relationship. However, subgroup analysis showed that prenatal ETS exposure was linked to higher risk of symmetric FT-LBW (OR: 2.26, 95%CI: 1.56-3.26) but not asymmetric FT-LBW. And maternal appetite explained only 6.45% of their relationship.Conclusions: Maternal prenatal ETS exposure increased risk of having symmetric FT-LBW infant, and appetite might mediate their relationship partially. This study emphasizes the importance of sample homogeneity and stresses the needs to improve the public awareness of the harmful effects of ETS.

Are women who quit smoking at high risk of excess weight gain throughout pregnancy?

Background

Smoking cessation has been reported to be associated with high total gestational weight gain (GWG), which itself is a risk factor for adverse maternal-infant outcomes. Recent studies have criticized conventional single measures of GWG, since they may lead to biased results. Therefore, we aimed to compare patterns of GWG based on serial antenatal weight measurements between women who: never smoked, quit during pregnancy, continued to smoke.

Methods

Participants (N = 509) of our longitudinal study were recruited from seven antenatal clinics in Southwestern Ontario. Serial GWG measurements were abstracted from medical charts, while information on smoking status was obtained from a self-administered questionnaire at a median gestational age of 32 (27–37) weeks. GWG patterns were assessed by fitting piecewise mixed-effects models. First trimester weight gains and weekly rates for the last two trimesters were compared by smoking status.

Results

During the first trimester, women who never smoked and those who quit during pregnancy gained on average 1.7 kg (95 % CI: 1.4–2.1) and 1.2 kg (0.3–2.1), respectively, whereas women who continued smoking gained more than twice as much (3.5 kg, 2.4–4.6). Weekly rate of gain in the second and third trimesters was highest in women who quit smoking (0.60 kg/week, 0.54–0.65), approximately 20 and 50 % higher than in women who never smoked and those who smoked during pregnancy, respectively.

Conclusions

In this longitudinal study to examine GWG by smoking status based on serial GWG measurements, we found that women who quit smoking experienced a rapid rate of gain during the last two trimesters, suggesting that this high-risk group may benefit from targeted interventions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12884-016-1056-z) contains supplementary material, which is available to authorized users.

Association of Restraint and Disinhibition to Gestational Weight Gain among Pregnant Former Smokers

INTRODUCTION

Gaining excessive weight during pregnancy is associated with immediate maternal and fetal complications as well as longer term obesity. Prepregnancy body mass index, age, and smoking cessation have been related to gestational weight gain (GWG); however, less is known about how eating behaviors, that may be amenable to modification and have been related to weight gain outside of pregnancy, affect GWG.

METHODS

The present study evaluated the relationship of dietary restraint and disinhibition to GWG in a sample of women (n=248) who quit smoking before or early in pregnancy. Women self-reported height and prepregnancy weight during their third trimester. GWG was calculated by subtracting prepregnancy weight from third trimester weight. The Three-Factor Eating Questionnaire assessed restraint and disinhibition.

RESULTS

Average GWG was 14.60 (±7.64) kg and 47% of women had a GWG greater than the Institute of Medicine recommendations. Linear regression models were used to examine restraint and disinhibition as correlates of GWG, and multinomial logistic regressions were utilized to determine whether eating behaviors were associated with inadequate or excessive GWG. Restraint was associated positively with total GWG, but disinhibition was not associated with GWG. Thus, conscious attempts to restrict intake were associated with GWG beyond the influence of covariates.

CONCLUSION

These findings highlight the potential influence of modifiable eating behaviors on GWG and demonstrate the need for additional research to determine how these behaviors relate to GWG over the course of pregnancy.

Prenatal smoking cessation intervention and gestational weight gain

BACKGROUND

Quitting smoking is often associated with weight gain and prenatal cessation may lead to increased gestational weight gain (GWG). Although previous reports have suggested a link between prenatal smoking cessation and GWG, no studies have examined the relationship between cessation and guideline-recommended GWG, and there is little information about the relationship between the timing of prenatal cessation and GWG. Thus, we examine GWG among women in a community prenatal smoking cessation program and assess the relationship between the timing of prenatal cessation GWG.

METHODS

Pregnant women from care clinics serving economically disadvantaged women who participated in a smoking cessation intervention offered free of charge, self-reported weight, and provided biochemical verification of smoking. Relationships between duration of cessation and GWG were evaluated in t-tests and regression models. GWG was calculated from self-reported weight before pregnancy and self-reported weight at the last visit before delivery.

FINDINGS

Women who quit earlier during pregnancy had greater GWG (16.9 ± 7.5 kg) than did those who never quit (13.6 ± 8.9). After adjusting for timing of weight assessment and prepregnancy body mass index, however, GWG was not different between women who did and did not quit.

CONCLUSION

Quitting earlier in pregnancy is associated with greater GWG, but women who do and do not quit do not differ on total GWG. Despite increased GWG with early cessation, the maternal and fetal health benefits of prenatal smoking cessation outweigh risks of potential risks of excessive GWG.

Valuing mother and child health: the intrauterine environment

The paper estimates the value a mother assigns to own health relative to child health. Estimation of relative health valuation requires the decomposition of a child health improvement into its direct effect on the child's health and its indirect effect, through improvements in maternal health. Failure to distinguish the impact of the direct and indirect effects can lead to biased estimates. We consider the intrauterine environment of a pregnant mother and her unborn child, where maternal health inputs are choice variables and her health affects child health. The empirical estimates suggest that mothers value child health up to six times higher than own health, and that the relative value depends on maternal consumption patterns and household characteristics.

Relapse to smoking and postpartum weight retention among women who quit smoking during pregnancy

Postpartum weight retention contributes to obesity risk in women. Given that most women who quit smoking as a result of pregnancy will resume smoking within 6 months postpartum and that there is a robust association between smoking and weight, we sought to evaluate postpartum weight retention as a function of postpartum smoking status among women who had quit smoking during pregnancy. Women (N = 183) with biochemically confirmed cigarette abstinence at the end of pregnancy were recruited between February 2003 and November 2006. Women self-reported demographic information and weight before pregnancy. Smoking status and weight were documented at the end of pregnancy and at 6, 12, and 24 weeks postpartum. Breastfeeding was reported at 6 weeks postpartum. Differences in weight retention by relapse status at each assessment were evaluated. To examine weight retention in the presence of conceptually relevant covariates, mixed models with log-transformed weight data were used. At 24 weeks postpartum, 34.6% of women remained abstinent. Women who remained abstinent throughout the 24-week period retained 4.7 ± 2.1 kg more than did women who had relapsed by 6 weeks postpartum, P = 0.03. This difference in postpartum weight retention was significant after controlling for relevant covariates (age, race, breastfeeding, and pregravid BMI). Resumption of smoking within the first 6 weeks following childbirth is associated with decreased postpartum weight retention, even after controlling for breastfeeding and pregravid weight. Interventions to sustain smoking abstinence postpartum might be enhanced by components designed to minimize weight retention.

Should gestational weight gain recommendations be tailored by maternal characteristics?

The authors tested whether the relation between gestational weight gain (GWG) and 5 adverse pregnancy outcomes (small-for-gestational-age (SGA) birth, large-for-gestational-age (LGA) birth, spontaneous preterm birth, indicated preterm birth, and unplanned cesarean delivery) differed according to maternal race/ethnicity, smoking, parity, age, and/or height. They also evaluated whether GWG guidelines should be modified for special populations by studying GWG and risk of at least 1 adverse outcome within different subgroups. Data came from a cohort of 23,362 normal-weight mothers who delivered singletons at Magee-Womens Hospital in Pittsburgh, Pennsylvania (2003-2008). Adequacy of GWG was defined as observed GWG divided by recommended GWG. The synergy analysis found that the combination of smoking, black race/ethnicity, primiparity, or short height with poor GWG was associated with an excess risk of SGA birth, while high GWG combined with each of these characteristics diminished risk of LGA birth in comparison with the same GWG among the women's counterparts. Nevertheless, there were no significant or meaningful differences in the risk of at least 1 adverse outcome between the GWG recommended by the Institute of Medicine in 2009 and the GWG that minimized risk of the composite outcome. These findings do not support the tailoring of GWG guidelines on the basis of a mother's smoking status, race/ethnicity, parity, age, or height among normal-weight women.

Interventions for promoting smoking cessation during pregnancy

BACKGROUND

Tobacco smoking in pregnancy remains one of the few preventable factors associated with complications in pregnancy, low birthweight, preterm birth and has serious long-term health implications for women and babies. Smoking in pregnancy is decreasing in high-income countries and increasing in low- to middle-income countries and is strongly associated with poverty, low educational attainment, poor social support and psychological illness.

OBJECTIVES

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

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (June 2008), the Cochrane Tobacco Addiction Group's Trials Register (June 2008), EMBASE, PsycLIT, and CINAHL (all from January 2003 to June 2008). We contacted trial authors to locate additional unpublished data.

SELECTION CRITERIA

Randomised controlled trials where smoking cessation during pregnancy was a primary aim of the intervention.

DATA COLLECTION AND ANALYSIS

Trials were identified and data extracted by one person and checked by a second. Subgroup analysis was conducted to assess the effect of risk of trial bias, intensity of the intervention and main intervention strategy used.

MAIN RESULTS

Seventy-two trials are included. Fifty-six randomised controlled trials (over 20,000 pregnant women) and nine cluster-randomised trials (over 5000 pregnant women) provided data on smoking cessation outcomes.There was a significant reduction in smoking in late pregnancy following interventions (risk ratio (RR) 0.94, 95% confidence interval (CI) 0.93 to 0.96), an absolute difference of six in 100 women who stopped smoking during pregnancy. However, there is significant heterogeneity in the combined data (I(2) > 60%). In the trials with the lowest risk of bias, the interventions had less effect (RR 0.97, 95% CI 0.94 to 0.99), and lower heterogeneity (I(2) = 36%). Eight trials of smoking relapse prevention (over 1000 women) showed no statistically significant reduction in relapse.Smoking cessation interventions reduced low birthweight (RR 0.83, 95% CI 0.73 to 0.95) and preterm birth (RR 0.86, 95% CI 0.74 to 0.98), and there was a 53.91g (95% CI 10.44 g to 95.38 g) increase in mean birthweight. There were no statistically significant differences in neonatal intensive care unit admissions, very low birthweight, stillbirths, perinatal or neonatal mortality but these analyses had very limited power.

AUTHORS' CONCLUSIONS

Smoking cessation interventions in pregnancy reduce the proportion of women who continue to smoke in late pregnancy, and reduce low birthweight and preterm birth. Smoking cessation interventions in pregnancy need to be implemented in all maternity care settings. Given the difficulty many pregnant women addicted to tobacco have quitting during pregnancy, population-based measures to reduce smoking and social inequalities should be supported.

Relationships between prenatal smoking cessation, gestational weight gain and maternal lifestyle characteristics

OBJECTIVES

To describe maternal characteristics and lifestyle factors associated with prenatal smoking habits and to appraise the effect of quitting smoking in early gestation on maternal weight gain during pregnancy.

METHODS

This is a follow-up study of 1753 women who gave birth in 1984/1985 in Stockholm, Sweden. Multivariate logistic models were used to evaluate the association between smoking cessation and weight gain above the American Institute of Medicine (IOM) recommendations, based on pre-pregnancy BMI.

RESULTS

About 22% of all participants identified themselves as current smokers and 11.6% reported smoking cessation during pregnancy. Smokers were more likely to be single mothers and reported low quality of breakfast (e.g. eating only 1 food group at breakfast). Non-smokers were older, more likely to be married and have a healthier lifestyle. Quitters also adopted healthier eating habits (e.g. improvement in their breakfast quality). Women who quit smoking gained, on average, 15.3 kg (SD 4.4) during pregnancy, non-smokers gained 14.1 kg (SD 4.0) and smokers gained 13.8 kg (SD 4.3). Quitters gained significantly more weight than both non-smokers and smokers (p<0.001). Smoking cessation was significantly associated with gaining weight above IOM recommendations, even after controlling for potential confounders (OR: 2.0; 95%CI: 1.4-3.0; p<or=0.0001).

CONCLUSIONS

In this population, smoking cessation in early pregnancy doubled the likelihood of gaining excess weight. This finding highlights the need for supportive measures to help control weight gain among women who quit smoking during pregnancy.

Prenatal weight gain following smoking cessation

OBJECTIVE

To evaluate the association of changes in smoking habit with maternal weight gain.

STUDY DESIGN

We questioned 4000 pregnant women > or =20 years about previous and current smoking habits during a second trimester visit to general prenatal clinics in 6 Brazilian cities, from 1991 to 1995, and followed their weight, through chart review, to term.

RESULTS

Of women who reported stopping smoking (915, 23% of the total), 240 (26.2%) stopped during pregnancy. The median number of cigarettes smoked/day among those who reported continued smoking (717, 18%) decreased from 10 to 5 with pregnancy. In linear regression models adjusting for age, educational attainment, ethnicity, prepregnancy body mass index, parity and clinical center, ex-smokers gained 1.03 kg (95%CI 0.59-1.46) more than those reporting never smoking, this difference being greater: 1.54 kg (95%CI 0.78-2.30) in those who reported quitting while pregnant. The size of weight gain in both continuing smokers and ex-smokers was proportional to the reduction in daily number of cigarettes smoked during pregnancy, being 0.38 kg (95%CI 0.07-0.68) greater for each 10 cigarettes reduced (p=0.007).

CONCLUSION

Decreasing the quantity of cigarettes smoked in pregnancy, although important for maternal and child health, is associated with maternal weight gain.

Combined effects of maternal smoking status and dietary intake related to weight gain and birth size parameters

OBJECTIVE

To investigate the interaction of smoking status and dietary intake during pregnancy and its relationship to maternal weight gain and birth size parameters.

DESIGN

An observational prospective study.

SETTING

Free-living conditions.

POPULATION

Four hundred and eight healthy pregnant Icelandic women.

METHODS

Maternal smoking status, lifestyle factors and dietary habits were evaluated with questionnaires. Intake of foods and supplements was also estimated with a semiquantitative food frequency questionnaire for the previous 3 months. All questionnaires were filled out between 11 and 15 weeks and between 34 and 37 weeks of gestation. Smoking status in relation to optimal and/or excessive weight gain during pregnancy was represented with logistic regression controlling for potential confounding factors.

MAIN OUTCOME MEASURES

Maternal weight gain, smoking status, dietary intake and birthweight.

RESULTS

Women who smoked throughout pregnancy were unlikely to gain optimal weight or more (OR 0.51, 95% CI 0.27-0.97), whereas smoking cessation in connection with pregnancy ('former smokers') doubled the risk of excessive weight gain (OR 2.03, 95% CI 1.24-3.35). The latter association was no longer significant after adjustment for dietary factors and other confounding factors. Former smokers ate the least amount of fruit and vegetables (fruit: 129 versus 180 and 144 g/day (median), P= 0.038; vegetables: 53 versus 76 and 72 g/day, P= 0.026 for former smokers, nonsmokers and smokers, respectively). Birthweight was lowest among infants born to smokers, but birthweight was similar for former smokers and nonsmokers (3583 +/- 491 g versus 3791 +/- 461 g and 3826 +/- 466 g, respectively; P= 0.003).

CONCLUSIONS

Smoking cessation in early pregnancy or pre-pregnancy is not associated with low birthweight. It is, however, associated with excessive maternal weight gain and a low fruit and vegetable intake.

Development of overweight associated with childbearing depends on smoking habit: The Coronary Artery Risk Development in Young Adults (CARDIA) Study

OBJECTIVE

To prospectively evaluate whether childbearing leads to development of overweight in women and to evaluate the role of other known risk factors.

RESEARCH METHODS AND PROCEDURES

A prospective, multicenter observational study, the Coronary Artery Risk Development in Young Adults (CARDIA) Study from 1986 to 1996, examined subjects at baseline and in follow-up years 2, 5, 7, and 10. Included were 998 (328 black and 670 white) nulliparous women, age 18-30 years, who were not overweight at baseline. Relative odds for incident overweight (BMI > or = 25 kg/m2) associated with parity change (0, 1, or 2+) and risk factors were estimated using discrete-time survival models adjusted for baseline and time-dependent covariates.

RESULTS

Parity change-association with development of overweight depended on smoking habit (interaction, p < 0.001). In multivariate adjusted models, 1 and 2+ births vs. 0, respectively, were associated with increased risk for development of overweight among never smokers [odds ratio (OR) = 2.66; 95% confidence interval (CI): 1.80, 3.93, and 2.10, 95% CI: 1.24, 3.56] and decreased risk among current smokers (OR = 0.41; 95% CI: 0.17, 0.96, and 0.36, 95% CI: 0.08, 1.65). Risk was increased for black vs. white race (OR = 3.49; 95% CI: 2.59, 4.69), frequent weight cycling (OR = 1.45; 95% CI: 1.03, 2.04), and high school education or less (OR = 2.21; 95% CI: 1.50, 3.26) and was decreased for highest physical activity quartile (OR = 0.62; 95% CI: 0.43, 0.90).

DISCUSSION

Childbearing contributes to development of overweight in nonsmokers but not in smokers, where development of overweight is less likely in women who bear children. Race, education, and behaviors are important factors in development of overweight in young women.

Interventions for promoting smoking cessation during pregnancy

BACKGROUND

Smoking remains one of the few potentially preventable factors associated with low birthweight, preterm birth and perinatal death.

OBJECTIVES

To assess the effects of smoking cessation programs implemented during pregnancy on the health of the fetus, infant, mother, and family.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register and the Cochrane Tobacco Addiction Group trials register (July 2003), MEDLINE (January 2002 to July 2003), EMBASE (January 2002 to July 2003), PsychLIT (January 2002 to July 2003), CINAHL (January 2002 to July 2003), and AUSTHEALTH (January 2002 to 2003). We contacted trial authors to locate additional unpublished data. We handsearched references of identified trials and recent obstetric journals.

SELECTION CRITERIA

Randomised and quasi-randomised trials of smoking cessation programs implemented during pregnancy.

DATA COLLECTION AND ANALYSIS

Four reviewers assessed trial quality and extracted data independently.

MAIN RESULTS

This review included 64 trials. Fifty-one randomised controlled trials (20,931 women) and six cluster-randomised trials (over 7500 women) provided data on smoking cessation and/or perinatal outcomes. Despite substantial variation in the intensity of the intervention and the extent of reminders and reinforcement through pregnancy, there was an increase in the median intensity of both 'usual care' and interventions over time. There was a significant reduction in smoking in the intervention groups of the 48 trials included: (relative risk (RR) 0.94, 95% confidence interval (CI) 0.93 to 0.95), an absolute difference of six in 100 women continuing to smoke. The 36 trials with validated smoking cessation had a similar reduction (RR 0.94, 95% CI 0.92 to 0.95). Smoking cessation interventions reduced low birthweight (RR 0.81, 95% CI 0.70 to 0.94) and preterm birth (RR 0.84, 95% CI 0.72 to 0.98), and there was a 33 g (95% CI 11 g to 55 g) increase in mean birthweight. There were no statistically significant differences in very low birthweight, stillbirths, perinatal or neonatal mortality but these analyses had very limited power. One intervention strategy, rewards plus social support (two trials), resulted in a significantly greater smoking reduction than other strategies (RR 0.77, 95% CI 0.72 to 0.82). Five trials of smoking relapse prevention (over 800 women) showed no statistically significant reduction in relapse.

REVIEWERS' CONCLUSIONS

Smoking cessation programs in pregnancy reduce the proportion of women who continue to smoke, and reduce low birthweight and preterm birth. The pooled trials have inadequate power to detect reductions in perinatal mortality or very low birthweight.

Cigarette Smoking and Low Maternal Weight Gain in Medicaid-Eligible Pregnant Women

OBJECTIVES

Weight gain during pregnancy (termed maternal weight gain) is an important predictor of maternal and infant health. This analysis was conducted to examine if cigarette smoking during pregnancy was associated with low maternal weight gain, as defined by the Institute of Medicine's (IOM) recommendations, independent of caloric intake.

METHODS

The participants were 265 Medicaid-eligible, pregnant women. Data were self-reported. Low maternal weight gain was defined as gaining less than the IOM recommendation for a given prepregnancy body mass index (BMI). Logistic regression was used to determine if smokers had greater odds of low maternal weight gain independent of caloric intake.

RESULTS

Approximately 21% of the participants were self-reported smokers. No difference was observed in mean maternal weight gain between smokers and nonsmokers (14.4 kg vs. 13.9 kg, respectively, p = 0.80). However, a greater proportion of smokers were categorized as having low maternal weight gain compared with nonsmokers (35.7% vs. 31.1%). Unadjusted regression analysis showed that the odds of low maternal weight gain were 1.34 times greater for smokers than nonsmokers (odds ratio [OR] = 1.34, 95% confidence interval [CI] 0.73, 2.67). The OR did not materially change after adjustment for daily caloric intake, age, and length of gestation. In addition, the data suggest that the more cigarettes smoked, the higher the odds of having low maternal weight gain.

CONCLUSIONS

The results suggest that cigarette smoking is associated with low maternal weight gain, as defined by the IOM recommendations, independent of caloric intake.

Effets maternels et fœtaux d'une prise de poids maternelle excessive au cours de la grossesse dans une population de patientes de poids normal avant la grossesse

OBJECTIVE

To study the effects of increased gestational weight gain in women of normal prepregnant weight.

PATIENTS AND METHODS

We compared 174 patients gaining more than 18 kg to 174 patients gaining between 9 and 15 kg. Body mass index was normal for every woman included in the study.

RESULTS

Weight gain > or =18 kg was associated with increased risk of vascular complications (5.2% vs. 1.1%, P < 0.05) but not with increased risk of mellitus diabetes (5.2% vs. 4.0%, NS). Weight gain > or =18 kg prolonged labor length (414.4 +/- 147 min vs. 376.5 +/- 166.4 min, P < 0.05) and increased the rate of cesarean section (19.5% vs. 10.3%, P < 0.05). Neonatal outcome was similar in both groups, mean birth weight was greater (3413.6 +/- 427.0 g vs. 3163.4 +/- 495.1 g, P < 0.05) and the frequency of infants weighing more than 4000 g at birth was increased (8.0% vs. 4.0%, P < 0.05) among women gaining more than 18 kg.

CONCLUSION

Excess weight gain in pregnancy affects gestational and delivery outcomes and results in higher frequency of fetal macrosomia. These results confirm recommendations on weight gain in pregnancy as guidelines for pregnant women.

Relationships between cigarette smoking during pregnancy, gestational age, maternal weight gain, and infant birthweight

OBJECTIVE

To estimate the effect of smoking on infant birthweight independent of gestational age and maternal weight gain during pregnancy.

METHODS

Stepwise regression was used to identify sets of maternal and infant characteristics not modified by prenatal smoking that were predictors of infant birthweight, gestational age, and net maternal weight gain. These were then included in regression analyses to assess the effects of smoking, as measured by cigarette consumption, exhaled carbon monoxide, or urinary cotinine on gestational age, net maternal weight gain, and infant birthweight.

RESULTS

After adjustment for nonmodifiable factors, smoking accounted for 1.5-3.1% of the variance in gestational age at delivery. It accounted for 5.3-7.7% of the variance in net maternal weight gain after adjustment for nonmodifiable factors and gestational age. After adjustment for gestational age and net maternal weight gain, and the nonmodifiable factors, smoking accounted for 2.7-5.2% of the variance in infant birthweight.

CONCLUSIONS

Most of the gain in infant birthweight on quitting smoking is due to the independent effect of smoking on fetal growth restriction, with much smaller gains related to increased maternal weight gain and a slightly longer gestational age.

Position of the American Dietetic Association: nutrition and lifestyle for a healthy pregnancy outcome

It is the position of the American Dietetic Association that women of childbearing potential should maintain good nutritional status through a lifestyle that optimizes maternal health and reduces the risk of birth defects, suboptimal fetal growth and development, and chronic health problems in their children. The key components of a health-promoting lifestyle during pregnancy include appropriate weight gain; consumption of a variety of foods in accordance with the Food Guide Pyramid; appropriate and timely vitamin and mineral supplementation; avoidance of alcohol, tobacco, and other harmful substances; and safe food-handling. Prenatal weight gain within the Institute of Medicine (IOM) recommended ranges is associated with better pregnancy outcomes. The total energy needs during pregnancy range between 2,500 to 2,700 kcal a day for most women, but prepregnancy body mass index, rate of weight gain, maternal age, and physiological appetite must be considered in tailoring this recommendation to the individual. The consumption of more food to meet energy needs and the increased absorption and efficiency of nutrient utilization that occurs in pregnancy are generally adequate to meet the needs for most nutrients. However, vitamin and mineral supplementation is appropriate for some nutrients and situations. This statement also includes recommendations pertaining to use of alcohol, tobacco, caffeine, street drugs, and other substances during pregnancy; food safety; and management of common complaints during pregnancy and specific health problems. In particular for medical nutrition therapy, pregnant women with inappropriate weight gain, hyperemesis, poor dietary patterns, phenylketonuria (PKU), certain chronic health problems, or a history of substance abuse should be referred to a qualified dietetics professional.

Weight concerns in women smokers during pregnancy and postpartum

When women smokers become pregnant, they are asked to control weight gain and at the same time to relinquish an addictive drug with weight suppressing effects. For women with serious body image concerns or a history of unhealthful eating patterns, smoking cessation may be particularly problematic. To investigate the relationship of weight concerns with smoking and weight gain during pregnancy and postpartum weight loss strategies, we conducted a retrospective study of women who had given birth to their first child within the past 10 years and were smokers when they became pregnant. We observed that women smokers with high weight and body image concerns (HC) gained significantly more weight during pregnancy-in amounts that far exceeded maximum recommended weight gain-than did women with low concerns (LC). HC were more likely to adopt smoking as a weight-control strategy and to be receptive to multiple weight-control strategies. Although they lost significantly more weight in the first month postpartum than did LC, they had also gained significantly more during pregnancy; the net result was that weight loss as a percentage of weight gained did not differ significantly between groups. HC were significantly less likely to experience food cravings in the first trimester and marginally less likely to vomit than LC. We conclude that early identification of high-risk women, coordination of prenatal care with smoking cessation counseling, and development of effective relapse prevention strategies that specifically address weight issues both during and after pregnancy will be needed if efforts to reduce smoking during pregnancy and postpartum are to be optimized.

Does parental smoking cessation discourage adolescent smoking?

BACKGROUND

We examined the relationship of smoking cessation in parents to smoking and uptake and cessation by their adolescent children.

METHODS

We analyzed a cross-sectional sample of 4,502 adolescents, ages 15-17 years, who lived in two-parent households that were interviewed as part of the 1992-1993 Tobacco Supplement of the Current Population Survey, which questioned householders 15 years of age and older about their smoking history. Ever smokers reported smoking at least 100 cigarettes in their lifetime. Former smokers were ever smokers who had quit.

RESULTS

Multivariate analyses, adjusted for demographic characteristics of adolescents, as well as father's age, education, and family income, found that adolescents whose parents had quit smoking were almost one-third less likely to be ever smokers than those with a parent who still smoked. Furthermore, adolescent ever smokers whose parents quit smoking were twice as likely to quit as those who had a parent who still smoked. Parental quitting is most effective in reducing initiation if it occurs before the child reaches 9 years of age.

CONCLUSION

Encouraging parents to quit may be an effective method for reducing adolescent smoking, through decreased uptake and increased cessation. The earlier parents quit, the less likely their children will become smokers.