Suppressed prolactin but normal neurophysin levels in cigarette smoking breast-feeding women

Nicotine directly affects milk production in lactating mammary epithelial cells concurrently with inactivation of STAT5 and glucocorticoid receptor in vitro

Nicotine from tobacco smoke is absorbed into the bloodstream and transferred into breast milk in breastfeeding mothers. Smoking causes a decrease in breast milk volume, adverse changes to the milk composition, and a shortened lactation period. Breast milk is produced by mammary epithelial cells (MECs) in mammary glands during lactation. However, it remains unclear whether nicotine directly affects milk production in lactating MECs. To address this issue, we prepared a culture model with high milk production ability and less-permeable tight junctions (TJs) by seeding mouse MECs on a cell culture insert. Lactating MECs showed expression of α2, α3, β2, and β4 of nicotinic acetylcholine receptors. The high concentration of nicotine at 10-100 μM inhibited β-casein secretion and caused abnormal localization of TJ proteins. We subsequently investigated whether nicotine at a physiological concentration could affect lactating MECs. Nicotine at 1.0 μM directly inhibited α- and β-casein secretion in lactating MECs concurrently with inactivation of STAT5 and glucocorticoid receptor without affecting the TJ barrier. Nicotine treatment also induced MEC apoptosis concurrently with inactivation of Akt. These results support the adverse effects of nicotine on breastfeeding in smoking mothers.

Effect of waterpipe tobacco smoke exposure during lactation on learning and memory of offspring rats: Role of oxidative stress

AIMS

The prevalence of waterpipe tobacco smoking is increasing among breastfeeding women. Herein, the effect of maternal waterpipe tobacco smoke (WTS) exposure during lactation on learning and memory of adult offspring rats was examined.

MAIN METHODS

Lactating rats received either fresh air or mainstream WTS (1 h twice daily) from day 4 to day 21. Learning and memory was examined by the radial arm water maze and the levels of brain derived neurotrophic factor (BDNF) and oxidative stress biomarkers superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase and thiobarbituric acid reactive substances (TBARS) were assessed in the hippocampus of adult male offspring rats.

KEY FINDINGS

Maternal exposure to WTS during lactation impaired the long-term memory and reduced levels of BDNF (P < 0.05) in hippocampus in adult male offspring rats. The activity of SOD, GPx and catalase were reduced (P < 0.05) while level of TBARS was increased (P < 0.05).

SIGNIFICANCE

Maternal WTS exposure during lactation impaired the long-term memory of adult male offspring that was associated with low levels of BDNF and altered oxidative stress balance. Therefore, careful measures should be taken to enhance waterpipe smoking cessation during breastfeeding.

Tobacco smoking and breastfeeding: Effect on the lactation process, breast milk composition and infant development. A critical review

Approximately 10% of women report smoking during pregnancy. The number of breastfeeding women who relapse back to smoking is even greater. Smoking may cause adverse changes to the milk's composition by not only reducing its protective properties, but also by affecting the infant's health. The pathophysiological mechanisms underlying these adverse effects are not entirely known. This article is a review of previous reports about the effects of smoking on the lactation process, breast milk composition and infant development. A systematic search for English language articles published until 2015 was made, using a MEDLINE data. The key search terms were "smoking and breastfeeding", "smoking and lactation", "smoking and milk composition", "nicotine and breast milk". Studies have shown that nicotine levels in breast milk of women who smoke are three times higher than those in the plasma levels. Breast milk volume is reduced and the duration of lactation period is shorter. Smoking causes adverse changes to the milk's composition by not only reducing its protective properties, but also affecting infants' response to breastfeeding and to breast milk.

Nutrition Recommendations in Pregnancy and Lactation

The nutritional status of a woman during pregnancy and lactation is not only critical for her health but for future generations. Although a nutritionist or registered dietitian can help facilitate dietary counseling and interventions, physicians also need to be cognizant of nutritional needs during pregnancy because they differ significantly compared with nonpregnant populations. Furthermore, an individualized approach to nutritional counseling that considers a woman's nutritional status and body mass index is recommended.

The influence of psychosocial factors on the duration of breastfeeding

Aim: A study was undertaken to examine to what extent psychosocial factors are related to the length of breastfeeding. Methods: A cohort of Danish mothers giving birth to a single child was followed up for four months. Information on mother and baby including psychosocial variables was obtained from a self-report questionnaire. Breastfeeding status was subsequently monitored by a health visitor. Results: A total of 471 (88%) mothers participated, 98.7 % initiated breastfeeding and after four months 277 (59%) were still exclusive breastfeeding; 99 mothers, 51% of those who stopped, stopped within the first five weeks. In Cox regression analyses the duration of breastfeeding showed a positive association with mother's schooling ( p=0.002), her intention to breastfeed ( p=0.001), previous experience with breastfeeding ( p<0.001), self-efficacy with respect to breastfeeding ( p<0.001), her confidence in breastfeeding ( p=0.012) and knowledge about breastfeeding ( p=0.001). The effect of the mother's knowledge depended on the parity of the child. Among primiparous mothers high knowledge was associated with long duration of breastfeeding, but this association was not found among the multiparous. Conclusions: To help the mothers who would like to breastfeed their baby, we must improve our ability to identify mothers at risk of early cessation. Mother's schooling, her intention, self-efficacy and earlier breastfeeding experience can be used as early predictors. An intervention should aim at improving the self-efficacy and resources of these mothers, with a focus on practical knowledge. The first five weeks, when the largest proportion of the cessations occurred, require special attention.

Effects of smoking, mother's age, body mass index, and parity number on lipid, protein, and secretory immunoglobulin A concentrations of human milk

AIM

This study investigated the effect of smoking, mother's age, body mass index (BMI), and parity number on density, lipids, proteins, and secreted immunoglobulin A (SIgA) of human milk.

METHODS

Transitional and mature milk samples were collected from 23 nursing smoker mothers and 43 nursing nonsmoker mothers. Proteins, lipids, and SIgA concentrations were determined as well as the milk density and the general protein profile.

RESULTS

Our investigation showed that the milk of smokers contained less lipids and proteins (statistically significant 26% and 12% decrease, respectively), whereas milk density was unchanged. SIgA concentration was 27% lower in milk from smokers, but the decrease was not statistically significant. The general protein profile showed no significant smoking-associated changes in the four identified proteins (β-casein, immunoglobulin A heavy chain, serum albumin, and lactoferrin). Mothers' age and residential area showed noticeable but statistically nonsignificant differences in some of the measured parameters. However, parity number, lactation stage, and BMI were associated with a significant modification of milk composition. Mature milk contained more lipids and less protein, whereas the increase of parity number was associated with an increase in lipid concentration. The group of overweight mothers showed lower milk protein concentration in comparison with the normal group. Multivariate analysis showed a statistically significant interaction effect of the variables (smoking, parity number, lactation stage, age, and BMI) on lipids and between some of them on proteins and SIgA.

CONCLUSION

Our study showed that smoking was associated with lower milk lipid and protein concentrations and that the parity number and BMI were associated with a change in milk lipids and proteins content, respectively.

Prosocial effects of oxytocin and clinical evidence for its therapeutic potential

There has been unprecedented interest in the prosocial effects of the neuropeptide oxytocin in humans over the last decade. A range of studies has demonstrated correlations between basal oxytocin levels and the strength of social and bonding behaviors both in healthy individuals and in those suffering from psychiatric disorders. Mounting evidence suggests associations between polymorphisms in the oxytocin receptor gene and prosocial behaviors and there may also be important epigenetic effects. Many studies have now reported a plethora of prosocial effects of intranasal application of oxytocin, including the domains of trust, generosity, socially reinforced learning, and emotional empathy. The main focus of this review will be to summarize human preclinical work and particularly the rapidly growing number of clinical studies which have identified important links between oxytocin and a wide range of psychiatric disorders, and have now started to directly assess its therapeutic potential.

Risk factors for cessation of breastfeeding prior to six months postpartum among a community sample of women in Calgary, Alberta

OBJECTIVES

To describe the rates of breastfeeding initiation and breastfeeding for at least six months and identify risk factors for failing to breastfeed for six months among a community sample of mothers in Calgary, Alberta.

METHODS

A cohort of women (n=1737) who participated in a longitudinal study of prenatal support and who could be contacted when their child was three-years-old (n=1147) were invited to participate in a follow-up telephone questionnaire. Of these 1147 women, 780 (69% participating rate) participated and provided breastfeeding data. Risk factors for early cessation of breastfeeding prior to six months were identified using bivariate and multivariable strategies.

RESULTS

Of the 780 women, 95.6% initiated breastfeeding and 71.6% continued to breastfeed for at least six months. Risk factors identified for early cessation included younger maternal age, obesity prior to pregnancy, lower maternal education, working full-time or intending to within the first year, history of depression, depression or anxiety during pregnancy, poor social support, and smoking during pregnancy (all p<0.05). Multivariable analysis revealed that working full-time or intending to within the first year, lower maternal education, obesity prior to pregnancy and anxiety during pregnancy most increased a woman's risk of early cessation (all p<0.05).

CONCLUSION

Nearly all mothers initiated breastfeeding and 70% continued to breastfeed for six months, although subgroups of women remained at an elevated risk of early cessation. Research to better understand breastfeeding decisions among women with the risk factors identified is needed to facilitate the development of more effective breastfeeding promotion strategies.

Smoking cessation in pregnancy

Managing smoking cessation during pregnancy is vital to the wellbeing of the fetus and the mother. Women who continue to smoke during pregnancy expose the fetus to thousands of chemicals which have been shown to cause deleterious short- and long-term effects. Although a large majority of women cease smoking early in the pregnancy, many of them relapse following delivery. Following a review of current research, an overview of the safety and efficacy of smoking cessation treatments for pregnant women will be considered. Limited research has been performed in this field; however, it can be concluded that low-dose intermittent nicotine replacement therapy is a safe treatment modality for women who smoke during pregnancy. At present there has been no research on other current smoking cessation treatments; however, we will suggest techniques to improve cessation rates and strategies to reduce relapse.

The long-term effects of prenatal nicotine exposure on neurologic development

A large body of documented evidence has found that smoking during pregnancy is harmful to both the mother and the fetus. Prenatal exposure to nicotine in various forms alters neurologic development in experimental animals and may increase the risk for neurologic conditions in humans. There is a positive association between maternal smoking and sudden infant death syndrome (SIDS); however, the connection between nicotine addiction, depression, attention disorders, and learning and behavior problems in humans is not straightforward. Nicotine's action on the production and function of neurotransmitters makes it a prime suspect in the pathology of these diseases. Nicotine accentuates neurotransmitter function in adults but desensitizes these functions in prenatally exposed infants and children. This desensitization causes an abnormal response throughout the lifespan. Furthermore, nicotine use by adolescents and adults can alleviate some of the symptoms caused by these neurotransmitter problems while they increase the risk for nicotine addiction. Although nicotine replacement drugs are used by pregnant women, there is no clear indication that they improve outcomes during pregnancy, and they may add to the damage that occurs to the developing neurologic system in the fetus. Understanding the effects of nicotine exposure is important in providing safe care for pregnant women, children, and families and for developing appropriate smoking cessation programs during pregnancy.

Association of maternal smoking status with breastfeeding practices: Missouri, 2005

OBJECTIVE

We sought to determine the association of smoking status as a risk factor for reduced initiation and duration of breastfeeding.

METHODS

The Missouri Pregnancy Related Assessment and Monitoring System collected a stratified sample of new mothers in 2005. Surveys were mailed, with telephone follow-up, and completed within 2 to 12 months after delivery. Respondents were classified as nonsmokers, smokers who quit during pregnancy, light smokers (<or=10 cigarettes per day), or moderate/heavy smokers (>10 cigarettes per day). Multivariable binomial regression and Cox proportional hazards models were used to assess breastfeeding initiation and duration according to smoking status.

RESULTS

Overall, 1789 women participated (weighted response rate: 61%). Approximately 74% of the women ever breastfed; 31% of the women ever smoked while pregnant. Compared with nonsmokers, the moderate/heavy smokers and light smokers were less likely to initiate breastfeeding, after controlling for sociodemographic characteristics, the presence of other smokers in the household, alcohol use, mode of delivery, and infant hospitalization. Compared with nonsmokers, the moderate/heavy smokers, light smokers, and smokers who quit during pregnancy were more likely to wean over time, controlling for the same covariates. There were no significant differences between nonsmokers and smokers regarding reasons for not initiating or ceasing breastfeeding.

CONCLUSIONS

Mothers who smoked initiated breastfeeding less often and weaned earlier than nonsmoking mothers. Incorporating knowledge of the association between smoking and breastfeeding into existing smoking-cessation and breastfeeding programs could provide opportunities to reduce perinatal exposure to tobacco smoke, improve interest in breastfeeding, and address other barriers to breastfeeding that smoking mothers may face.

Breastfeeding and smoking among low-income women: results of a longitudinal qualitative study

BACKGROUND

The benefits of breastfeeding for infants and mothers have been well established, yet rates of breastfeeding remain well below national recommendations in the United States and even lower for women who smoke during pregnancy. Primary goals of this study were to explore contextual factors that contribute to breastfeeding intentions and behavior and to examine how smoking status affected women's decision making about breastfeeding.

METHODS

This paper is based on a longitudinal qualitative study of smoking, pregnancy, and breastfeeding among 44 low-income women in the southwest U.S. who smoked during pregnancy. Each woman was interviewed 9 times; 6 times during pregnancy and 3 times postpartum using semistructured questionnaires. Interviews lasted 1 to 3 hours and were tape-recorded, transcribed, and analyzed.

RESULTS

Despite 36 (82%) respondents stating that they intended to breastfeed for an average duration of 8 months, rates of breastfeeding initiation and duration were much lower than intentions. By 6 months postpartum, only two women were breastfeeding exclusively.

CONCLUSIONS

Women perceived that a strong risk of harming the baby was posed by smoking while breastfeeding and received little encouragement to continue breastfeeding despite an inability to stop smoking. The perceptions of the toxic, addictive, and harmful effects of smoking on breastmilk constitution and quantity factored into reasons why women weaned their infants from breastfeeding much earlier than the recommended 6 months. The results indicate a need for more consistency and routine in educating women on the relationship between smoking and breastfeeding and in promoting breastfeeding in spite of smoking postpartum.

Prenatal exposure to passive smoking and duration of breastfeeding in nonsmoking women: Krakow inner city prospective cohort study

INTRODUCTION

The relationship between tobacco smoking in pregnancy and breastfeeding is of public health importance. The present birth cohort study provided the opportunity to investigate whether the negative relationship between passive smoking measured by the cotinine concentrations in maternal blood at delivery and breastfeeding in postpartum could also be confirmed in nonsmoking mothers.

MATERIALS AND METHODS

The study sample included 441 healthy pregnant women who were recruited in the first and second trimester of pregnancy. Enrollment included only nonsmoking women of the age of 18-35 years with singleton pregnancies, without illicit drug use and free from chronic diseases. After delivery, breastfeeding duration was defined using the answers recorded in the interviews with mothers conducted every 3 months. An infant was considered to be fully breastfed when breast milk was the only source of nourishment. Any breastfeeding was defined as an infant's being fully breastfed or receiving both breast milk and formula, with or without solids. In the statistical analysis only total duration of breastfeeding up to 6 months was considered for both forms of breastfeeding. Subjects were categorized into environmental tobacco smoke (ETS) exposure groups according to maternal blood cotinine level at delivery or self-reported exposure to ETS during pregnancy.

RESULTS

The adjusted relative risk of discontinuation of any breastfeeding after infant's first 6 months was more than two times higher (OR = 2.42; 95% CI: 1.42-4.14) in women whose blood cotinine level at delivery was above 75th percentile of cotinine distribution (>0.15 ng/mL); the corresponding risk of discontinuation of full breastfeeding was OR = 1.71; 95% CI: 1.03-2.82. Estimated relative risk of discontinuation of any breastfeeding based on self-reported ETS was also significant but much less marked; the corresponding risk of discontinuation of full breastfeeding was insignificant.

CONCLUSION

The results obtained support the hypothesis that ETS may affect breastfeeding duration and support the avoidance of passive smoking as a necessary additional measure for breastfeeding promotion.

Breast feeding twins and high multiples

Breast feeding offers major health advantages for all infants, whether born singleton or from multiple pregnancy. Adequate quantity and quality of milk production has been documented even for high multiples. Combined efforts of parents, close family, friends, and the medical team can help to make either full or partial breast feeding of multiples possible.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Very low level environmental exposure to lead and prolactin levels during pregnancy

Lead (Pb) is a well-known poison interfering with calcium homeostasis and dopaminergic pathway. We hypothesized that environmental Pb exposure can interact with prolactin (PRL) secretion, regulated by calcium and dopamine, during pregnancy and in fetus. The objective of this longitudinal study was to determine the relationships between blood Pb concentration and serum PRL levels in 101 pregnant women recruited during pregnancy and their fetuses exposed to low environmental levels of Pb. We observed a significant negative relationship between maternal blood Pb concentrations and maternal serum PRL levels. Cord blood PRL was weakly correlated with blood Pb levels. Our results suggest that maternal physiological parameters in pregnancy can be modulated by low level of Pb exposure and indicate a particular susceptibility of pregnant women to its toxic effects.

Smoking and hormones in health and endocrine disorders

Smoking has multiple effects on hormone secretion, some of which are associated with important clinical implications. These effects are mainly mediated by the pharmacological action of nicotine and also by toxins such as thiocyanate. Smoking affects pituitary, thyroid, adrenal, testicular and ovarian function, calcium metabolism and the action of insulin. The major salient clinical effects are the increased risk and severity of Graves' hyperthyroidism and opthalmopathy, osteoporosis and reduced fertility. Smoking also contributes to the development of insulin resistance and hence type 2 diabetes mellitus. An important concern is also the effect of smoking on the foetus and young children. Passive transfer of thiocyanate can cause disturbance of thyroid size and function. Furthermore, maternal smoking causes increased catecholamine production, which may contribute to under perfusion of the foetoplacental unit.

As influências ambientais e a interação homem-ecossistema no planejamento e implementação da atenção à saúde materno-infantil na prática de enfermagem

Este ensaio teórico tem como objetivo ressaltar a importância a ser dada pelo enfermeiro à questão ambiental e, especificamente, à poluição ambiental, no planejamento e implementação de ações de saúde, no que se refere à reprodução e a saúde materno-infantil. São apontados alguns efeitos de poluentes sobre a fertilidade, resultados gestacionais e crescimento e desenvolvimento da criança. É questionado o conhecimento do enfermeiro sobre esses aspectos e apresentadas considerações sobre a necessidade de aprofundar a investigação para identificar fatores de risco ambientais para a reprodução e saúde do binômio mãe-filho. A aquisição desse conhecimento pode ser uma das estratégias adotadas para que a atenção ao ambiente, incluindo as inter-relações homem-ecossistema, transforme-se em subsídio real para a adoção, pelo enfermeiro, de novas práticas em saúde. Finalmente, enfatiza a necessidade de que o enfermeiro participe em equipes multidisciplinares, nas quais sejam abordadas questões de risco para a saúde decorrentes do ambiente.

Maternal education and the incidence and duration of breast feeding: a prospective study

INTRODUCTION

Duration of breast feeding and factors possibly affecting duration were studied in a population of 2174 newborn infants, with gestational age of >37 weeks, who were born in the Department of Obstetrics and Gynaecology at the University of Florence Hospital between November 15, 1997, and November 14, 1998.

PATIENTS AND METHODS

Nine hundred mothers agreed to participate in the study. Five questionnaires were completed at the end of the 1st, 3rd, 6th, 9th, and 12th postpartum month. These dealt with infant feeding practices, including breast feeding during the previous week. Breast feeding duration was defined as short (1 month); medium-short (>1 month-<3 months); medium (>3-<6 months); medium-long (>6-<9 months), and long (>9 months).

RESULTS

The authors found that 76.3%, 64.7%, 42.3%, 26.4%, and 17% of mothers were still breast feeding at 1, 3, 6, 9, and 12 months after delivery, respectively. The multivariate analysis of the correspondence shows that lack of breast feeding is associated with a birth weight of less than 3000 g, a low level of maternal education, and maternal profession as a housewife or blue collar worker in the commercial sector. A period of breast feeding defined as short or medium-short is associated with mothers who smoke, primiparous mothers, and absence of maternal allergy. The survival curves highlight how the single factor of smoking is an element that leads to a significant difference in the duration of breast feeding. The multiple Cox regression analysis shows a significant negative influence associated with birth weight of less than 3000 g, maternal smoking, and first parity. Above all, among low-birth-weight infants of mothers who smoke, there is a strong correlation with a shorter duration of breast feeding.

DISCUSSION

There is still a need for programs that support and encourage breast feeding, focusing particularly on mothers with a low level of education who give birth to a low-weight infant, primiparous mothers, and smokers.

Association between smoking during pregnancy and breastfeeding at about 2 weeks of age

Maternal smoking during pregnancy may decrease breastfeeding, in part perhaps by decreasing milk supply; furthermore, prenatal smoking is a predictor of postpartum smoking. In this study, birth certificate data, including maternal smoking, for 1998 Oregon resident live births were linked to newborn screening data obtained from Oregon's Newborn Screening Program (NSP), allowing study of risk factors for failure to breastfeed. NSP collects information on infant feeding before newborn discharge and again at about 2 weeks postpartum. Feeding data and risk factor data were available after a probability match of the newborn screening and birth certificate data sets, respectively, for 36,324 (80.3%) of the 45,228 resident live births. Prenatal maternal tobacco use was significantly associated with failure to exclusively breastfeed at about 2 weeks of age (adjusted odds ratio = 2.08, 95% confidence interval = 1.94, 2.21). Women who smoked during pregnancy were less likely to breastfeed than women who did not smoke during pregnancy.

Does maternal smoking have a negative physiological effect on breastfeeding? The epidemiological evidence

BACKGROUND

Women who smoke are less likely to breastfeed their children than nonsmokers. It is thought that nicotine has a negative effect on breastmilk supply by suppressing prolactin levels. The aim of this review was to assess the epidemiological evidence that maternal smoking has a negative physiological effect on breastfeeding.

METHODS

The following data sources were searched: The Cochrane Library, Medline, CINAHL, Current Contents, Psychinfo, Sociological Abstracts and the Lactation Resource Centre (Australian Breastfeeding Association) using the key words "smoking" and "breastfeeding" or "infant feeding." The Journal of Human Lactation and Birth were hand searched.

RESULTS

Women who smoke are less likely to intend to breastfeed, less likely to initiate breastfeeding, and likely to breastfeed for a shorter duration than nonsmokers. Several studies have found a dose-response relationship between the number of cigarettes smoked each day and breastfeeding intention, initiation, and duration that persists after adjusting for confounding factors. In some population groups a high proportion of smokers breastfeed successfully.

CONCLUSIONS

The association between maternal smoking and lack of breastfeeding is consistent across different study designs in a range of countries. Given that women who smoke are less likely to intend to breastfeed, however, it cannot be assumed that the relationship between smoking and duration of breastfeeding is a physiological one. If smoking had a consistent negative physiological effect on lactation, one would not expect to see such wide variations in breastfeeding rates among women who smoke. Therefore, it is likely that psychosocial factors are largely responsible for the lower rates of breastfeeding found in women who smoke compared with those who do not.

Maternal smoking and reduced duration of breastfeeding: a review of possible mechanisms

AIM

To systematically review the possible mechanisms by which maternal smoking affects lactation.

METHODS

Databases (Medline, CINAHL, Current Contents, Psychinfo, Sociological Abstracts and the Cochrane Library) were searched for smoking and breastfeeding or infant feeding. The Journal of Human Lactation and Birth were hand-searched, searches were also conducted at NMAA's Lactation Resource Centre and references cited were located where appropriate. Articles were divided into the various ways that smoking could affect breastfeeding and were tabulated.

RESULTS

Most studies were conducted on small samples of animals or humans; the majority were prior to 1985. Most animal studies exposed the animals to much greater levels of nicotine than those to which humans are exposed. Most studies did not examine if breastfeeding behaviour was similar in smokers and non-smokers, and did not consider that any physiological difference found could be the result of poor lactation practices, rather than the cause of poor lactation in smokers. The definition of breastfeeding infants was also problematic in many studies. The effect of smoking on oxytocin in women was only examined in one study, and no effect was found, yet a negative effect of smoking on oxytocin release is reported in the breastfeeding literature.

CONCLUSION

Although there is consistent evidence that women who smoke breastfeed their infants for a shorter duration than non-smokers, the evidence for a physiological mechanism is not strong.

Measurement of nine human milk proteins by nephelometric immunoassays: application to the determination of mature milk protein profile

OBJECTIVES

Microparticle-enhanced nephelometric immunoassays for six human milk proteins (beta-casein, kappa-casein, alpha-lactalbumin, serum albumin, lactoferrin, and lysozyme) and conventional immunonephelometry assays for immunoglobulin A, C3, and C4 complement proteins were developed and characterized.

DESIGN AND METHODS

Microparticle-enhanced nephelometric immunoassays are competitive assays based on the nephelometric quantification of the inhibition of microparticle-protein conjugates immunoagglutination by the proteins to be assayed.

RESULTS

High precision (CVs ranged from 1% to 14% in within- and between-assays) and recovery (linear recovery in dilution-overloading assay) ensure a reliable determination of the main human milk proteins by single-step homogeneous nephelometric immunoassays, accurate over wide ranges of concentration. These immunoassays were easily applied to a large number of mature human milk samples (between 373 and 503 according to the proteins tested).

CONCLUSIONS

The immunoassays developed could be applied to the fast determination of human milk protein profile usable for nursery milk bank and fortification.

Infant feeding practices in Ottawa-Carleton: the introduction of solid foods

Infant feeding guidelines regarding the introduction of solid foods are generally not well known in Canada. The guidelines recommend that solid foods be introduced between four to six months of age, depending on the developmental readiness of the infant. In order to understand the underlying factors and patterns which contribute to the introduction of solid foods in infants, data were analyzed from three cross-sectional surveys of parents of six-month-old infants from the Ottawa-Carleton region (n = 373, 1988; n = 330, 1992; n = 338, 1996) conducted by the Ottawa-Carleton Health Department. Multivariable analysis showed that mothers who: did not breastfeed, were younger, had lower education, smoked or had partners that smoked, and lacked support after birth, were more likely to introduce solid foods before four months of age. These data support the need for nutrition education programs to increase adherence to the new Nutrition for Healthy Term Infants guidelines.

Breastfeeding experience and milk weight in lactating mothers pumping for preterm infants

BACKGROUND

Research about parity or breastfeeding experience and its relationship with milk production in humans is limited. The purpose of this study was to determine if any difference in milk volume occurred among mothers with and without breastfeeding experience who used either a single or double breast pumping regimen the first 5 weeks postpartum.

METHODS

A convenience sample of 39 mothers of nonnursing preterm infants participated from two tertiary care centers in the midwestern United States. The sequential single pumping group consisted of 20 mothers, 7 of whom had previous breastfeeding experience; the simultaneous double pumping group consisted of 19 mothers, 2 of whom had previous breastfeeding experience. Income and pumping group regimen were used as blocking variables, and average frequency of kangaroo care per week and average frequency of breast pumping per week were covariants in the repeated measures analysis of variance.

RESULTS

Mothers with previous breastfeeding experience had greater milk weights over time, but weights were not significantly different when compared with those mothers with no previous breastfeeding experience. Additional analysis with the covariants of pumping frequency and kangaroo care, and with the independent variables of group, breastfeeding experience, and income resulted in statistically significantly greater milk yield in the women with previous breastfeeding experience.

CONCLUSIONS

The findings of the two repeated analyses indicated the complexity of the milk production response, and the importance of considerations of environmental as well as physiologic factors.

Smoking relapse and early weaning among postpartum women: is there an association?

BACKGROUND

Smoking in the postpartum period may contribute to early weaning, although the nature and temporal aspect of the relationship are poorly understood. The objective of this study was to examine the association between early weaning and smoking relapse among women who stopped smoking during pregnancy.

METHODS

A secondary analysis of data from a randomized controlled trial was conducted. The participants were 228 women who had stopped smoking for pregnancy, who participated in a smoking relapse prevention trial, and who breastfed. Women who relapsed to daily smoking postpartum were compared with those who remained abstinent or smoked occasionally. The dependent variable was breastfeeding for less than 26 weeks (early weaning). Potential covariates included intended duration of breastfeeding, parity, partner's smoking, nicotine dependence, emotional health, return to paid employment, and various sociodemographic variables.

RESULTS

Approximately two-thirds (65.1%) of the women who relapsed to daily smoking weaned before 26 weeks compared with 33.8 percent of the women who remained abstinent or smoked occasionally. Controlling for intended duration of breastfeeding, education, and return to paid employment, women who resumed daily smoking were almost four times more likely to wean early than those who abstained or smoked occasionally.

CONCLUSIONS

Early weaning may result from psychological or physiological changes associated with tobacco use. Smoking relapse prevention in the postpartum period may be one of the most effective interventions in ensuring that women who stop smoking for pregnancy remain stopped and breastfeed their babies for the recommended duration.

Breast-feeding and drug exposure

Breast-feeding provides important benefits to mother and infant and should be strongly encouraged as the optimal feeding choice for most infants. In the mother with an ongoing illicit drug abuse problem, the risks posed to the infant are substantial and outweigh the benefits of breast-feeding in most cases. Moderate use of alcohol, cigarettes, or caffeine is compatible with breast-feeding.

The incidence and duration of breast feeding

Information obtained from a variety of sources shows different rates of initiation and duration of breast feeding and different supplementation strategies. Among populations of developing countries, in general, the mothers resident in rural-areas are more likely to breast feed than those in urban areas; in addition the better off or more highly educated are less likely to breast feed. In contrast in the developed countries, the better educated and the higher social class mothers are more likely to breast feed. There is some evidence that delay in initiation of breast feeding, lack of professional support, conflicting advice from health professionals and the presence of free samples of artificial milk (whether or not given to the mother) can result in a mother failing to establish breast feeding. Additionally, mothers who smoke cigarettes are less likely to breast feed successfully. Whilst breast feeding is almost universal in a number of developing countries, many also commonly use complementary feeds. In some countries, particularly in Asia, it is still commonplace for a child not to be given the mother's colostrum, and therefore for the first breast feed to occur well after the first 24 h.

Influences on breastfeeding in southeast England

Factors associated with not exclusively breastfeeding at discharge from the obstetric hospital and with duration of breastfeeding were examined in 700 randomly sampled infants. Obstetric records were examined in 97.7% of the subjects and 73.0% of subject families were interviewed. There were 444 (66.5%) infants exclusively breastfed at discharge from the obstetric hospital. Factors associated with not exclusively breastfeeding at discharge from the obstetric hospital after adjusting for potential confounders were: mother leaving school aged less than 18 years, mother not attending antenatal classes and the use of a dummy in the 2 weeks before the interview. Bed sharing practice in the 2 weeks before the interview was associated with exclusively breastfeeding at discharge from the obstetric hospital. Factors associated with a shorter duration of breastfeeding were: mother leaving school before 18 years of age, smoking 20 or more cigarettes per day and use of a dummy. Dummy use may causally reduce breastfeeding or might be a marker for breastfeeding difficulties. There was a dose-response relationship with smoking, with heavier smokers breastfeeding for the shortest time periods. Bed sharing was associated with a longer duration of breastfeeding. This may not necessarily be a causal relationship because breastfeeding may promote bed sharing. The effect of dummy use and bed sharing on breastfeeding warrants further study.

Breast-feeding in Iceland. Predictive factors and effects of interventive measures

The aim of this study was to analyse how long babies born in Akureyri district in 1990 were breast-fed, compared with babies born in 1985. Possible predictive factors for the length of breast-feeding were studied by univariate and multivariate analyses. From 1985 to 1990, the proportion of infants exclusively breast-fed at the age of 3 months increased from 57% to 70% (p < 0.01) and for those breast-fed exclusively or partially, from 67% to 83% (p < 0.01). By 1990, 64% of all babies were breast-fed at the age of 6 months, compared with 43% in 1985 (p < 0.01). The factor with the strongest correlation with a long breast-feeding period was a well educated father. Other factors correlated with the duration of breast-feeding were the mother's age, number of previous children, attending a maternity course, and being a non-smoker. It is concluded that real beneficial changes regarding the duration of breast-feeding in Iceland have been observed during the last decade, but the objectives of the preventive measures recommended by health authorities have not yet been reached.

Factors associated with the age of introduction of solids into the diet of New Zealand infants. New Zealand Cot Death Study Group

OBJECTIVE

To describe the current timing of the introduction of solids in infancy and the factors influencing the decision to introduce solids.

METHODOLOGY

Eighteen hundred infants were selected randomly as part of the New Zealand Cot Death Study. Of these, 88% of the parent/caregivers were interviewed when their infant was aged between 1 and 12 months. They were asked when solids were first introduced into the diet.

RESULTS

By 12 weeks of age more than 20% of infants had been given solids; by 16 weeks and by 6 months 50 and 90% of babies, respectively, had been given solids. Maternal smoking, low educational achievement and not being breast-fed exclusively to 4 weeks of age were factors which were strongly associated with the early introduction of solids.

CONCLUSION

Half of New Zealand infants are being started on solids earlier than is presently recommended. More education is needed to promote the later introduction of solid foods into the diet.

Infant insufficient milk syndrome associated with maternal postpartum hemorrhage

Insufficient milk syndrome is defined as failure to thrive in infants due to insufficient daily breastmilk intake. This discussion examines a possible association between insufficient milk syndrome and maternal postpartum hemorrhage. Ten consecutive cases of insufficient milk syndrome associated with maternal postpartum hemorrhage were identified. The mothers presented between 3 and 35 days postpartum. Maternal postpartum blood loss ranged from 500-1500 ml in eight cases (mean: 963 ml); in two cases, blood loss was noted as 400++ and 200++, respectively. Six mothers experienced a drop of hemoglobin by > 30g/L; two had a drop in blood pressure > 30mmHg for > 20 minutes. All infants were failing to thrive. Five infants suffered hypernatremic dehydration with serum sodium levels ranging from 148-166mmol/L. Breastmilk electrolytes were measured in six cases, and elevated sodium levels, ranging from 21-100mmol/L, in five cases. These data serve to heighten awareness of insufficient milk syndrome as a potential consequence of postpartum hemorrhage. Early postpartum review of all breastfeeding mothers and infants is strongly encouraged.

Factors adversely associated with breast feeding in New Zealand

Control data from 1529 infants studied in a multicentre case-control study of sudden infant death in New Zealand were analysed to identify factors that might hinder the establishment and duration of breast feeding. Although 1300 infants (85%) were exclusively breast-fed at discharge from the obstetric hospital, this fell to 940 (61%) by 4 weeks. Logistic regression was used to identify factors that might adversely influence breast feeding 'at discharge', 'at 4 weeks' and the overall 'duration' of breast feeding. When adjusted for confounding factors, not exclusive breast feeding 'at discharge' was significantly associated with: twin pregnancy, being a Pacific Islander, mother not bedsharing, subsequent dummy use, birthweight less than 2500 g, heavy maternal smoking, not attending antenatal classes and mother less than 20 years old at first pregnancy. Mothers smoking more than 20 cigarettes a day were nearly twice as likely to not exclusively breast feed on discharge compared to those who did not smoke. A 'dose response' was apparent with the heaviest smokers having the least likelihood of establishing exclusive breast feeding. Being exclusively breast-fed at discharge but not 'at 4 weeks' was associated with: twin pregnancy, admission to a neonatal intensive care unit, subsequent dummy use and not being married. A shorter overall 'duration' of breast feeding was associated with maternal smoking, subsequent dummy use, mother not bedsharing, twin pregnancy, mother less than 20 years old at first pregnancy, low occupational status and not attending antenatal classes. These effects persisted when social and demographic factors, including birthweight, were taken into account.(ABSTRACT TRUNCATED AT 250 WORDS)

The Copenhagen cohort study on infant nutrition and growth: duration of breast feeding and influencing factors

Duration of breast feeding was studied in 249 randomly chosen, healthy, term infants of Danish origin of which 80.7% participated. Breast feeding was initiated by 99.5% of the mothers. At 3, 6 and 9 months, 71%, 52% and 33%, respectively, were still breast feeding. Only 1 infant (0.5%) was exclusively breast fed beyond 7 months of age. In a Cox multiple regression analysis of factors influencing duration of breast feeding, we found a positive association with maternal education (p < 0.001) and age (p = 0.02) and a negative association with the amount of formula given at the maternity ward (p < 0.001). Six months after delivery, 79% of the mothers with higher school education (> or = 12 years) were still breast feeding, compared to 29% with a low school education (< or = 9 years). There is still a need for an increased effort to support mothers in breast feeding, focusing particularly on younger mothers with short school education. Formula supplements during the first days of life, given to 73% of the infants, were associated with a shorter duration of breast feeding and should be discouraged.

Smoking and breastfeeding: an overview

This paper reviews what is presently known about the associations between cigarette smoking, breastfeeding and infant health. Smoking almost certainly reduces lactational capacity. Tobacco constituents and combustion by-products reaching the infant through breastmilk or by inhalation are cause for concern. But artificially-fed infants are similarly exposed to many such compounds, and they in addition are at greater risk of respiratory and gastrointestinal disease, allergic disorders, and cot death. Hence breastfeeding must continue to be encouraged, even for smoking mothers. Recommendations that may reduce infant morbidity from smoking by the breastfeeding mother are set out. The author concludes that the scientific literature indicates that it is far from ideal to smoke and breastfeed--but it is worse to smoke and not breastfeed.

Maternal cigarette smoking, breast-feeding, and respiratory tract infections in infancy. A matched-pairs study

The importance of mothers' smoking habits for the occurrence of respiratory tract infections (RTIs) in their children during their infant years was studied. A group of 28 infants of mothers who smoked was compared with 28 infants of non-smokers. The pairs were matched with respect to mother's age, marital status, occupation, and parity. During their first year of life, the smokers' children were treated with antibiotics because of RTIs more often than the non-smokers' children (p = 0.046). The number of RTIs in the two groups were 38 and 19, respectively. However, infants of mothers who smoked were breast-fed for a shorter period than those of non-smokers (p = 0.028), the mean values being 4.5 and 6.7 months.

Acute respiratory illness in Adelaide children: breast feeding modifies the effect of passive smoking

STUDY OBJECTIVE

The aim was to investigate the relation between passive smoking and childhood acute respiratory illness.

DESIGN

The study involved an initial postal survey on a random sample of children followed by a case-control study based on the survey. A respiratory illness score was calculated from maternal reports of episodes of illness in the previous 12 months.

SETTING

The study was a population survey based on Adelaide metropolitan area in South Australia.

PARTICIPANTS

The reference population (n = 13,996) was all live born children registered in South Australia in 1983 whose parents lived in Adelaide metropolitan area. Of these, 4985 families were contacted by post and from 2125 respondents, 1218 (58%) gave consent for home interview. "Cases" were children with respiratory illness scores in the top 20%, controlling for age and time of year (n = 258); "controls" were taken in the bottom 20% (n = 231).

MEASUREMENTS AND MAIN RESULTS

Maternal smoking in the first year of life was associated with a doubling in relative odds of respiratory proneness in the child (odds ratio = 2.06, 95% CI 1.25-3.39) after adjustment for confounding by parental history of respiratory illness, other smokers in the home, use of group child care, parent's occupation, and levels of maternal stress and social support. There was no evidence that this association was attributable to differences in the way smoking and non-smoking parents perceived or managed childhood acute respiratory illness. Maternal smoking in the first year, without smoking in pregnancy, was also associated with increased risk of respiratory proneness (odds ratio 1.75, 95% CI 1.03-3.0), showing an effect of passive smoking independent of any in utero effect. There was a strong negative effect modification by breast feeding: relative odds of respiratory proneness with maternal smoking were seven times higher among children who were never breast fed than among those who were breast fed.

CONCLUSIONS

The results suggest a relatively small but real effect of passive smoking on childhood acute respiratory illness. Effect modification by breast feeding may be due to a combination of behavioural and biological mechanisms.

Drinking and smoking at 3 months postpartum by lactation history

A spontaneous decrease in maternal drinking and smoking often occurs during pregnancy. The present study was conducted to determine if these lower levels of maternal drinking and smoking during pregnancy persist into the postpartum period, and if so, to determine if they are related to breastfeeding. Drinking and smoking were estimated in three cohorts of postpartum women who had been followed since pregnancy. The first group never breastfed their infants; the second group breastfed for less than 1 month; the third group breastfed for more than three months. (Women who weaned between one and three months were not studied). Drinking and smoking in all three groups decreased sharply during pregnancy but rose again in the 3 months after delivery, though not to levels that were reported before conception. Usual drinking in the third month postpartum did not differ significantly among the three lactation groups. However, women who were still nursing were less likely to report occasional episodes of heavy drinking (binges) in this month than women who had weaned early or never breastfed. Women nursing in the third month postpartum were also significantly less likely to smoke during the month; if smoking, they were less likely to smoke heavily. These differences in postpartum drinking and smoking were not due entirely to habits before conception or to the influence of other potentially confounding variables.

The antiestrogenic effect of cigarette smoking in women

Epidemiologic results indicate that women who smoke cigarettes are relatively estrogen-deficient. Smokers have an early natural menopause, a lowered risk of cancer of the endometrium, and an increased risk of some osteoporotic fractures. Moreover, women who smoke may have a reduced risk of uterine fibroids, endometriosis, hyperemesis gravidarum, and benign breast disease. Several possible mechanisms for these effects have been identified. Smoking does not appear to be clearly related to estradiol levels, at least in postmenopausal women, although levels of adrenal androgens are increased. Moreover, smoking appears to alter the metabolism of estradiol, leading to enhanced formation of the inactive catechol estrogens.

Negative correlation of cigarette smoking and dysmenorrhea: reduced prostaglandin synthesis due to beta-endorphin, nicotine, or acrolein antagonism

It is suggested that the mechanism for decreased incidence of dysmenorrhea in female cigarette smokers may lie in the possible inhibition of algesic prostaglandins smoking induced stimulation of beta-endorphin, nicotine, or acrolein.