Maternal lifestyle characteristics during pregnancy, and the risk of obesity in the offspring: a study of 5,125 children
© Mourtakos et al.; licensee BioMed Central. 2015
Received: 25 November 2014
Accepted: 10 March 2015
Published: 21 March 2015
To investigate the association between gestational weight gain, maternal age and lifestyle habits (e.g., physical activity, smoking, and alcohol consumption) during pregnancy, with Body Mass Index of the offspring at the age of 8.
Α random sample of 5,125 children was extracted from a national database and matched with their mothers. With the use of a standardised questionnaire, telephone interviews were carried out for the collection of information like: maternal age at pregnancy, gestational weight gain (GWG), exercise levels, smoking and alcohol consumption. The Body Mass Index (BMI) status of the offspring at the age of 8 was calculated from data retrieved from the national database (e.g., height and weight).
The odds for being overweight/obese at the age of 8 for 1 kg GWG, for smoking, and for mild exercise during pregnancy compared to sedentary was 1.01 (95%CI: 1.00, 1.02), 1.23 (95%CI: 1.03, 1.47) and 0.77 (95%CI: 0.65, 0.91), respectively. Further analysis revealed that offspring of women who exceeded the Institute of Medicine (IOM) maternal weight gain recommendations were at an increased risk of obesity (OR: 1.45; 95%CI, 1.26, 1.67) compared with offspring of women with GWG within the recommended range. Maternal age and alcohol consumption were not associated with the outcome (p > 0.05).
GWG, physical activity and smoking status during pregnancy were significantly associated with obesity for the offspring at the age of 8. Health care professionals should strongly advise women to not smoke and to perform moderate exercise during pregnancy to prevent obesity in the offspring in later life.
At the dawn of the 21st century the larger part of humanity faces two major epidemics: the sedentary lifestyle and the obesity epidemic. These two usually co-exist, act synergistically to affect the health of individuals, and affect people regardless of sex and age . Among the countries of the European Union, more than half of the adult population is classified as overweight or obese, based on their Body Mass Index (BMI) ≥ 25 .
Obesity during pregnancy increases the risk for adverse outcomes both in maternal and offspring health (e.g., pre-eclampsia, gestational diabetes, hypertension, birth by caesarean section, etc.) [3,4]. These are significant concerns for women who are obese at the time of conception, but health risks increase dramatically as mothers gain excessive weight during pregnancy. The extra weight gained during pregnancy may remain after successive pregnancies and it is possibly related to adverse outcomes in the health of the mother . According to the 2009 Institute of Medicine (IOM) recommendations, about 42% of women began pregnancy in 2004–2007 as overweight or obese and 51.2% gained excessive weight (>23 kg) during their pregnancy . These findings along with the increasing incidence of obesity suggest that problems associated with the aforementioned parameters will also emerge in the future.
Researchers that have conducted observational studies report an association of childhood obesity with specific characteristics of pregnancy such as maternal obesity before pregnancy and gestational weight gain (GWG) [7-10]. GWG has also been associated with greater offspring BMI in childhood and early adulthood .
Childhood obesity is a worldwide epidemic [12,13]. The number of overweight children is expected to rise by 1.3 million per year, with more than 300,000 of these children becoming obese each year . Greece is among the European countries with the highest levels of childhood obesity and studies report a dramatic increase in its prevalence (52%) . Moreover, in the last decade a significant increase was observed, (~30%), in the rates of overweight 8 to 9 year old children of both genders in Greece [15-17].
Maternal health before and during pregnancy and perinatal factors such as physical activity, smoking and alcohol consumption during pregnancy may play an important role in the health, development, and BMI status of the offspring in the future . Many prospective studies show that childhood obesity is associated with specific characteristics of pregnancy, such as maternal obesity, GWG, birth weight, pregnancy smoking status, alcohol consumption, gestational diabetes , and breast feeding .
Although obesity in childhood and preadolescence is increasing with alarming rates, long-term epidemiological data that investigate the link between maternal characteristics during pregnancy and obesity status of their offspring in childhood and preadolescence are limited. Current evidence suggests that GWG, smoking and alcohol consumption, as well as exercise during pregnancy independently could be associated with the development of childhood obesity [7,19]. However, no study has ever examined the effect of all the aforementioned variables taken together. Thus, the aim of the present study was to determine how maternal age, GWG, exercise levels during pregnancy, alcohol consumption and smoking are related to obesity of the offspring in preadolescence (e.g., 8 years). The findings of this analysis will provide information on appropriate interventions during pregnancy that could potentially prevent childhood and preadolescence obesity.
Population-based data, derived from 11 national school-based health surveys, were obtained from a database that included anthropometric data (e.g., weight, height, etc.), as well as contact details of almost all Greek children who attended primary school during 1997–2007, with the exception of 2002 (e.g., total sample 671,715 primary school pupils, aged 7–9 years old), following an official request to the Greek Ministry of Culture and the Ministry of Education. The national database included anthropometric data and information on age, gender, city and area, home address and telephone number, which were collected yearly, at the same time period (spring), from 1997 to 2007, with the exception of 2002, in almost all schools of Primary Education (roughly 85%); schools that did not participate were from borderland areas, with small numbers of children. Thus, from 1997 to 2007, a total of 651,582 8- to 9-year-old children (51% boys and 49% girls, over 95% of the total student population) participated in the study. Measurements were performed by two trained Physical Education (PE) teachers in each school. PE teachers followed a specific protocol taught in corresponding seminars held by the Greek General Secretariat of Sports (GSS). The same protocol was employed in all schools.
A sample of 5,500 children (0.8% of the entire population) was randomly extracted from the database and their mothers were contacted by telephone. Random extraction was performed through statistical software. The number of 5,500 subjects was adequate to achieve statistical power greater or equal to 99% for evaluating a 0.10 ± 0.05 change in the regression coefficients at 5% significance level of two-sided tested hypotheses. The random sampling was stratified according to the region and place of living (e.g., rural/urban), according to the National Statistical Agency and equally distributed during the study period (i.e., 500 mothers per year). The women that refused to participate in the study were 183 (3.3%). The sample of mother-child dyads covered all geographical regions of Greece (e.g., mainland Greece and the islands). All mothers had Greek nationality.
The information of the proposed protocol was collected through telephone interviews based on the Computer Aided Telephone Interviews (CATI) method. In order to validate the process, 100 face-to-face interviews were conducted to check for discrepancies with the information collected by telephone. No such discrepancies were noted in any of the variables evaluated.
All the necessary information was collected using a standardised questionnaire, named the Childhood Obesity Pregnancy Determinants (ChOPreD) questionnaire, designed and developed with the collaboration of the Harokopeio University Department of Nutrition & Dietetics and Department of Geography and the University of Texas Medical Branch Department of Internal Medicine. The ChOPreD questionnaire was tested and internally revised by study’s investigators during a pilot study, which confirmed its construct validity.
During data collection, the mothers were asked to provide information contained in their pregnancy ultrasound records (e.g., body weight) and recall certain information (e.g., exercise levels, smoking patterns and alcohol consumption). Mothers in Greece have ultrasounds at the start of the pregnancy and several times during its progress and receive records of the results. Only mothers that had full set of records were included in the study, which finalised the sample of 5,125 mother-children dyads. Data recall relating to the perinatal period is very common in pregnancy-related studies.
The BMI data for the children was calculated based on data retrieved from the national database. The BMI status of the offspring at the age of 2 and 8 was determined based on cut-off points suggested by Cole . GWG was calculated based on the difference between the mother’s weight at the last and first visits, based on ultrasound records. Relative GWG was calculated based on the difference between last and first visit compared to first visit.
For the purposes of the current study, physical activity is defined as any form of bodily movement produced by skeletal muscles that increases energy expenditure over the level of physical rest, thereby offering numerous benefits for the human body. This can include a wide range of activities, such as leisure activities, participation in organised sports, exercise, physical work, etc. . The assessment of the exercise was based on frequency (e.g., Never 0 times/wk, Rare 1 time/wk, Often 3–6 times/wk, Daily 7 times/wk), and duration (e.g., exercise more than the recommended 30 minutes) of physical activity. The questionnaire did not evaluate intensity, as only mild intensity exercise is recommended during pregnancy .
Cardio-respiratory fitness exercises were recorded as aerobic activities, whereas the ones that involved concentric and eccentric contractions of skeletal muscle exercise were classified as resistance activities . The questionnaire took into account activities undertaken during recreation, exercise or sport, as well as daily activities (e.g., activities one does at work, as part of house and yard work, etc.). Mothers were instructed to refer to all domains of physical activity during their pregnancy. If a mother did not participate in any type of activity she was classified as inactive.
The study was approved by the Bioethics Committee of Harokopio University. Oral approval was obtained from all mothers who agreed to participate in the study and written informed consent was obtained from those participants who took part in the validation process of the study.
Continuous variables were presented as mean values and standard deviations (SD) since they were normally distributed (as examined by the use of histographs and P-P plots) and as median and 1st and 3rd quartile. Categorical variables were presented as absolute and relative frequencies. Offspring BMI obesity status (normal weight vs. overweight/obese) and BMI categories for mothers were calculated according to the proposed cut off points suggested by International Obesity Task Force (IOTF). In order to assess the potential effect of the following maternal characteristics: GWG, smoking during pregnancy, alcohol consumption during pregnancy and level of physical exercise on the offspring’s obesity status, binary logistic regression analysis was implemented and odds ratios (OR) with the corresponding 95% confidence intervals (CI) were calculated. Further adjustments were made for the effect of maternal age at pregnancy, birth weight, maternal weight status pre-pregnancy and history of breastfeeding. Prior to that, every possible effect modification between the proposed risk factors and the confounders was examined, but all interaction terms were not statistical significant (p-values > 0.05). The Hosmer and Lemeshow’s goodness-of-fit test was calculated in order to evaluate the model’s goodness-of-fit and residual analysis was implicated using the dbeta, the leverage, and Cook’s distance D statistics in order to identify outliers and influential observations. All analyses were performed using the SPSS version 18.0 software for Windows (SPSS Inc., Chicago, IL, USA). Statistical significance level from two-sided hypotheses was set at the 5% level (p ≤ 0.05).
Baseline characteristics of mothers and offspring
Characteristics of the studied sample of mothers and their offspring
Birth weight, Kg
BMI at age 8 (child), Kg/m 2
Maternal age at pregnancy, years
Gestational weight gain (GWG), Kg
Maternal BMI status in first visit, n(%)
Maternal BMI status in last visit, n (%)
Sometimes per week
Smoking status during pregnancy, n (%)
Alcohol consumption, n(%)
Determinants of offspring‘s’ obesity status
Results (OR, 95%CI, p ) from logistic regression models that used to evaluate the association of maternal characteristics with offspring BMI status (overweight/obesity vs. normal weight) at the age of 8 years
Univariate models(1)OR 95% CI
Full model (2) OR 95% CI
Full model, plus confounders (3) OR 95% CI
GWG, per 1 Kg
Smoking status during pregnancy (Yes vs. No)
Alcohol consumption during pregnancy (Yes vs. No)
Exercise level during pregnancy
Moderate vs. sedentary
Sometimes per week vs. sedentary
Often vs. sedentary
Daily vs. sedentary
The aim of the present work was to investigate the association between GWG, maternal age and various lifestyle habits, like physical activity, smoking, and alcohol consumption during pregnancy, with body weight of the offspring at the age of 8. It was revealed that GWG, physical activity and smoking status during pregnancy were significantly associated with obesity for the offspring at the age of 8 years. Moderate exercise during pregnancy was found to lower the risk of the offspring to develop overweight/obesity in childhood and preadolescence, even after adjusting for various maternal and offspring characteristics.
The pregnancy period is a phase in a woman’s life in which she develops a greater awareness about her health. During pregnancy, women are given a significant opportunity to amend some unhealthy habits, like smoking and alcohol consumption, to adopt a more active lifestyle, and to participate in physical activities and/or exercise. The development and introduction of specific recommendations for physical activity for pregnant women is relatively recent. The investigation of physical activity among pregnant women began in the last quarter of the 20th century and continues to this day. More specifically, early investigations in the 1970s and 1980s included a very cautious approach and focused mainly on possible adverse effects for the health of pregnant women, primarily because of the limited knowledge about its response of pregnant women to exercise and the even more limited knowledge about the effects on pregnancy. Only recently, researchers have begun to focus on the potential benefits to the health of mothers and their offspring that are related to participation in exercise during pregnancy. The Guide for Physical Activity in the US for 2008 was a crucial point, as it contained inter alia a well-written and substantiated chapter on the role of physical activity during pregnancy and after it [24,25]. Based on the recommendations proposed in the Guide and the recommendations of other countries, it is suggested that pregnant healthy women can exercise at the same level as non-pregnant women, especially early in the pregnancy. According to evidence gathered from the Behavioural Risk Factor Survey that was conducted in 2000, Evenson and Wen report that more than two thirds of pregnant women said that they participated in some type of leisure physical activity . Since the prevalence of pregnant women’s participation in physical activities is increasing, it is important to understand the potential risks and the possible benefits of physical activity during pregnancy for women and their offspring.
Despite the fact that the benefits of exercise for the wider population have been internationally accepted, the claims for its beneficial effects during pregnancy have not yet been substantiated [27-31] and exercise is not yet sufficiently well accepted as being beneficial for pregnant women. Health scientists are still sceptical and often reluctant to encourage exercise during pregnancy, despite the well-recognised benefits. One of the main concerns associated with exercise during pregnancy is the effect of the activity to the foetus, as any benefits to the mother can be offset by adverse effects to the foetus. Although the concerns are theoretically associated with the selective redistribution of blood flow during exercise and the transport of CO2 and O2, and nutrients by the placenta, it has been shown that moderate exercise seems to cause minimal to moderate increase in foetal heart rate by approximately 10–30 beats/minute above baseline . On the contrary, physical activity during pregnancy has been shown to improve the health status of both the mother and the foetus. Moreover, maternal exercise may reduce the risk for certain risk factors of pregnancy-related complications, such as gestational diabetes according to many studies [31-34].
In accordance with the guidelines for prenatal physical activity in the United States, the American College of Obstetrics and Gynaecology (ACOG) currently recommends that pregnant women are allowed to undertake 30 or more minutes of moderate exercise on most, if not all days of the week, if there are no health problems and obstetric complications . Recommendations for physical activity from the American Ministry of Health published in 2008, state that pregnant women must participate in at least 150 minutes of moderate-intensity aerobic exercise a week, even if they did not participate in such activities before pregnancy . The American College of Sports Medicine (ACSM) recommends at least 3 sessions of exercise lasting at least 15 minutes and whose duration will increase gradually to 30 minutes a day, preferably all days of the week . The recommendations are similar in Canada , Denmark , Great Britain , Norway  and Australia .
Another significant risk factor during pregnancy is related to smoking. It is a common and preventable specific adverse environmental exposure for the foetus . Maternal smoking during pregnancy is associated with foetal growth retardation and increased risk of preterm delivery and low birth weight [43,44]. Maternal smoking during pregnancy also seems to increase the risk of obesity in the offspring [45,46].
Regarding smoking during pregnancy, the results from the present study are in line with other studies that show that exposure to smoking during foetal life leads to overweight and obesity in childhood. A systematic review showed that prenatal exposure to maternal cigarette smoking led to a 50% increased risk of overweight at the age of 3–33 years old . Also, a recent meta-analysis showed that maternal smoking during pregnancy was associated with obesity in children with an average age of 9 years . It has also been suggested that there is a dose-response relationship between the number of cigarettes smoked and the risk of childhood obesity . Several studies have also shown an association between maternal smoking during pregnancy with the highest BMI in the offspring or the increased risk of obesity in later life [45,49-51].
Moreover, it has been argued that exposure of the developing foetus to nicotine may adversely affect the development of the function of the hypothalamus and through this mechanism to have an effect on appetite control during later life and consequently to increase the risk of future obesity . Furthermore, studies showed that children of mothers who smoked had a higher BMI at 1 year of age , and in separate studies, increased BMI was also evident at the age of 6.5 years , 8 years , even in 33 years .
Finally, another survey  recently showed that teenagers in late adolescence that had been exposed to smoking as foetuses showed higher values of subcutaneous fat (26%) and endo-abdominal fat (33%). Overall, while the weight gain in children from the mother’s smoking is small, the results are long-termed.
Several studies in recent years have evaluated the reliability of recalled information relating to the perinatal period. Specifically, studies have been conducted involving recall intervals from 7 to 22 years and on the whole concluded that this information is reliable [57-59].
An earlier survey by Villar et al. (1988) showed high correlation between measured and recalled variables, such as anthropometric measurements of the mother and the offspring, but low correlation to factors such as physical activity during pregnancy and blood pressure . Finally, a review of studies that employed physical activity questionnaires during pregnancy compared to ones that employed objective measurements (e.g. accelerometers) showed that the association between them was low to moderate . Hence the results, as in the present investigation, should be interpreted with caution.
The information that was collected during the telephone interviews was self-reported, and although mothers could provide information based on health records for themselves, this forms a limitation of the study. Moreover, a potential limitation of the study was that in the current cohort 17.3% of women were overweight/ obese before their pregnancy, a relatively low prevalence in comparison to published reports for the corresponding population [61,62]. This could be attributed to deliberate under-reporting, over-reporting or recall bias for the self-reported pre-pregnancy anthropometric data (body weight and height) . Similar observations have been previously reported in Greece by Manios et al., 2009  and is a common limitation in similar studies .
Finally, the sample of mothers included in the study did not show statistically significant levels of other risk factors related to intrauterine or foetal growth (i.e., gestational diabetes, increased blood pressure, etc.). Thus, the researchers concentrated their analysis only on the risk associated with GWG, maternal age at pregnancy, alcohol consumption, smoking and exercise.
The authors report no conflict of interest in the reporting of the data.
The research analysis that was conducted confirmed that when a mother gains more weight, adopts sedentary behaviour and smokes during pregnancy, the risk that her offspring will be overweight or obese (e.g., higher BMI) at the ages of 8 increases significantly.
Health care professionals should advise women to limit their GWG to the range specified for their pre-pregnancy BMI according to IOM guidelines, not to smoke and consume alcohol, and do moderate exercise during pregnancy.
The authors want to thank the study subjects for their willingness to participate. We are also very grateful to Mrs Chrysoula Alexi, Stavroula Parastatidou and Klairi Georgelli for their assistance with the data collection. This study was conducted with the support of the Institute for Translational Sciences at the University of Texas Medical Branch, supported in part by a Clinical and Translational Science Award (UL1TR000071) from the National Center for Advancing Translational Sciences, National Institutes of Health, OPAP SA – Greece, and support from the Harokopeio University Post Graduate program on Nutrition and Dietetics.
- Dugan SA. Exercise for preventing childhood obesity. Phys Med Rehabil Clin N Am. 2008;19(2):205–16.View ArticlePubMedGoogle Scholar
- Kosti RI, Panagiotakos DB. The epidemic of obesity in children and adolescents in the world. Cent Eur J Public Health. 2006;14(4):151–9.PubMedGoogle Scholar
- Lee CF, Hwang FM, Liou YM, Chien LY. A preliminary study on the pattern of weight change from pregnancy to 6 months postpartum: a latent growth model approach. Int J Obes (Lond). 2011;35(8):1079–86.View ArticleGoogle Scholar
- Villamor E, Cnattingius S. Interpregnancy weight change and risk of adverse pregnancy outcomes: a population-based study. Lancet. 2006;368(9542):1164–70.View ArticlePubMedGoogle Scholar
- Walsh JM, Murphy DJ. Weight and pregnancy. BMJ. 2007;335(7612):169.View ArticlePubMedPubMed CentralGoogle Scholar
- Park S, Sappenfield WM, Bish C, Salihu H, Goodman D, Bensyl DM. Assessment of the Institute of Medicine recommendations for weight gain during pregnancy: Florida, 2004–2007. Matern Child Health J. 2011;15(3):289–301.View ArticlePubMedGoogle Scholar
- Rooney BL, Mathiason MA, Schauberger CW. Predictors of obesity in childhood, adolescence, and adulthood in a birth cohort. Matern Child Health J. 2011;15(8):1166–75.View ArticlePubMedGoogle Scholar
- Mamun AA, Callaway LK, O’Callaghan MJ, Williams GM, Najman JM, Alati R, et al. Associations of maternal pre-pregnancy obesity and excess pregnancy weight gains with adverse pregnancy outcomes and length of hospital stay. BMC Pregnancy Childbirth. 2011;11:62.View ArticlePubMedPubMed CentralGoogle Scholar
- Schack-Nielsen L, Michaelsen KF, Gamborg M, Mortensen EL, Sørensen TI. Gestational weight gain in relation to offspring body mass index and obesity from infancy through adulthood. Int J Obes. 2010;34(1):67–74.View ArticleGoogle Scholar
- Gaskins RB, LaGasse LL, Liu J, Shankaran S, Lester BM, Bada HS, et al. Small for gestational age and higher birth weight predict childhood obesity in preterm infants. Am J Perinatol. 2010;27(9):721–30.View ArticlePubMedPubMed CentralGoogle Scholar
- Arenz S, Von Kries R. Protective effect of breast-feeding against obesity in childhood (2009): can a meta-analysis of published observational studies help to validate the hypothesis? Adv Exp Med Biol. 2009;639:145–52. Review.View ArticlePubMedGoogle Scholar
- James WPT. The epidemiology of obesity: the size of the problem. J Intern Med. 2008;263:336–52.View ArticlePubMedGoogle Scholar
- Martorell R, Kettel Khan L, Hughes ML, Grummer-Strawn LM. Overweight and obesity in preschool children from developing countries. Int J Obes Relat Metab Disord. 2000;24:959–67.View ArticlePubMedGoogle Scholar
- Tambalis KD, Panagiotakos DB, Kavouras SA, Kallistratos AA, Moraiti IP, Douvis SJ, et al. Eleven-year prevalence trends of obesity in Greek children: first evidence that prevalence of obesity is levelling off. Obesity (Silver Spring). 2010;18(1):161–6.View ArticleGoogle Scholar
- Tambalis KD, Panagiotakos DB, Psarra G, Sidossis LS. Inverse, but independent trends in obesity and fitness levels among Greek children: a time-series analysis from 1997 to 2007. Obes Facts. 2011;4(2):165–74.View ArticlePubMedGoogle Scholar
- Tambalis KD, Panagiotakos DB, Sidossis LS. Greek children living in rural areas are heavier but fitter compared to their urban counterparts. A comparative, time-series analysis (1997–2008). J Rural Health. 2011;27(3):270–7.View ArticlePubMedGoogle Scholar
- Chalkias C, Papadopoulos AG, Benekos G, Tambalis K, Psarra G, Sidossis L. Spatial variability of childhood obesity in response to socioeconomic heterogeneity. The case of Athens Metropolitan area, Greece. Proceedings of the 17th European Colloquium on Quantitative and Theoretical Geography (ECQTG2011), ed. S. Kalogirou, ISBN: 978-960-87751-1-4, 2011. p. 605–61.
- Wrotniak BH, Shults J, Butts S, Stettler N. Gestational weight gain and risk of overweight in the offspring at age 7 y in a multicenter, multiethnic cohort study. Am J Clin Nutr. 2008;87(6):1818–24.PubMedGoogle Scholar
- Seneviratne SN, Parry GK, McCowan LM, Ekeroma A, Jiang Y, Gusso S, et al. Antenatal exercise in overweight and obese women and its effects on offspring and maternal health: design and rationale of the IMPROVE (Improving Maternal and Progeny Obesity Via Exercise) randomised controlled trial. BMC Pregnancy Childbirth. 2014;14:148.View ArticlePubMedPubMed CentralGoogle Scholar
- Cole TJ, Flegal KM, Nicholls D, Jackson AA. Body mass index cut offs to define thinness in children and adolescents: international survey. Br Med J. 2007;335(7612):194.View ArticleGoogle Scholar
- Kendrick JS, Williamson DF, Caspersen CJ. Re: “A meta-analysis of physical activity in the prevention of coronary heart disease”. Am J Epidemiol. 1991;134(2):232–4.PubMedGoogle Scholar
- Evenson KR, Chasan-Taber L, Symons Downs D, Pearce EE. Review of self-reported physical activity assessments for pregnancy: summary of the evidence for validity and reliability. Paediatr Perinat Epidemiol. 2012;26(5):479–94.View ArticlePubMedPubMed CentralGoogle Scholar
- American College of Sports Medicine. ACSM’s Guidelines for Exercise Testing and Prescription. 6th ed. Philadelphia: Lippincot, Williams and Wilkins; 2000.Google Scholar
- ACSM. American College of Sports Medicine Position Stand and American Heart Association. Recommendations for cardiovascular screening, staffing, and emergency policies at health/fitness facilities. Med Sci Sports Exerc. 1998;30(6):1009–18.Google Scholar
- Garber CE, Blissmer B, Deschenes MR, Franklin BA, Lamonte MJ, Lee IM, et al. American College of Sports Medicine position stand. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: guidance for prescribing exercise. Med Sci Sports Exerc. 1998;43(7):1334–59.View ArticleGoogle Scholar
- Evenson KR, Wen F. Measuring physical activity among pregnant women using a structured one-week recall questionnaire: evidence for validity and reliability. Int J Behav Nutr Phys Act. 2010;7:21.View ArticlePubMedPubMed CentralGoogle Scholar
- Stevenson L. Exercise in pregnancy. Part 2: Recommendations for individuals. Can Fam Physician. 1997;43:107–11.PubMedPubMed CentralGoogle Scholar
- Artal R, Posner M. Fetal responses to maternal exercise (1991). In: Artal R, Wiswell RS, Drinkwater B, editors. Exercise in Pregnancy. 2nd ed. Baltimore, Md: Williams & Wilkins; 1991. p. 213–24.Google Scholar
- Saftlas AF, Logsden-Sackett N, Wang W, Woolson R, Bracken MB. Work, leisure-time activity, and risk of preeclampsia and gestational hypertension. Am J Epidemiol. 2004;160:758–65.View ArticlePubMedGoogle Scholar
- Sorensen TK, Williams MA, Lee I, Dashow EE, Thompson ML, Luthy DA. Recreational physical activity during pregnancy and risk of preeclampsia. Hypertension. 2003;41:1273–80.View ArticlePubMedGoogle Scholar
- Dye TD, Knox KL, Artal R, Aubry RH, Wojtowycz MA. Physical activity, obesity, and diabetes in pregnancy. Am J Epidemiol. 1997;146(11):961–5.View ArticlePubMedGoogle Scholar
- American College of Obstetricians and Gynecologists. Exercise during pregnancy and the postpartum period ACOG Committee Opinion No. 267. Obstet Gynecol. 2002;99:171–3.Google Scholar
- American College of Sports Medicine. Impact of physical activity during pregnancy and postpartum on chronic disease risk: Roundtable consensus statement. Med Sci Sports Exerc. 2006;38:989–1006.View ArticleGoogle Scholar
- Dempsey JC, Sorensen TK, Williams MA, Lee IM, Miller RS, Dashow EE, et al. Prospective study of gestational diabetes mellitus risk in relation to maternal recreational physical activity before and during pregnancy. Am J Epidemiol. 2004;159(7):663–70.View ArticlePubMedGoogle Scholar
- Physical Activity Guidelines Advisory Committee. Physical Activity Guidelines for Americans. US Dept of Health and Human Services; 2008.
- American College of Sports Medicine. Exercise prescription for healthy populations and special considerations. In: Thompson WR, editor. Guidelines for Exercise Testing and Prescription. 8. Philadelphia: Wolters Kluwer, Lippincott Williams & Wilkins; 2010. p. 183–7.Google Scholar
- Davies GA, Wolfe LA, Mottola MF, MacKinnon C, Arsenault MY, Bartellas E, et al. Exercise in pregnancy and the postpartum period. J Obstet Gynaecol Can. 2003;25(6):516–29.View ArticlePubMedGoogle Scholar
- Denmark National Board of Health. Physical activity- a handbook on prevention and treatment. Copenhagen, Denmark: National Board of Health; 2003.Google Scholar
- National Collaborating Centre for Women’s and Children’s Health (UK) (2008). Antenatal care: routine care for the healthy pregnant woman, NICE Clinical Guidelines, No. 62. London: RCOG Press; 2008.Google Scholar
- Directorate for Health and Social Affairs. Guidelines for Antenatal Care. Oslo, Norway: Directorate for Health and Social Affairs; 2005.Google Scholar
- Sports Medicine Australia. Exercise in pregnancy. http://sma.org.au/wp-content/uploads/2009/10/WIS-ExPreg.pdf.
- Neovius K, Rasmussen F, Sundstro MJ, Neovius M. Forecast of future premature mortality as a result of trends in obesity and smoking: nationwide cohort simulation study. Eur J Epidemiol. 2010;10:703–9.View ArticleGoogle Scholar
- Cnattingius S. The epidemiology of smoking during pregnancy: smoking prevalence, maternal characteristics, and pregnancy outcomes. Nicotine Tob Res. 2004;6:125–40.View ArticleGoogle Scholar
- Andres RL. Perinatal complications associated with maternal smoking. Semin Neonatol. 2005;5:231–41.View ArticleGoogle Scholar
- Von Kries R, Toschke AM, Koletzko B, Slikker Jr W. Maternal smoking during pregnancy and childhood obesity. Am J Epidemiol. 2002;156:954–61.View ArticleGoogle Scholar
- Ino T. Maternal smoking during pregnancy and offspring obesity: meta-analysis. Pediatr Int. 2010;52:94–9.View ArticlePubMedGoogle Scholar
- Oken E, Levitan EB, Gillman MW. Maternal smoking during pregnancy and child overweight: systematic review and metaanalysis. Int J Obes. 2008;32:201–10.View ArticleGoogle Scholar
- Suzuki K, Ando D, Sato M, Tanaka T, Kondo N, Yamagata Z. The association between maternal smoking during pregnancy and childhood obesity persists to the age of 9–10 years. J Epidemiol. 2009;3:136–42.View ArticleGoogle Scholar
- Mamun AA, Lawlor DA, Alati R, O’Callaghan MJ, Williams GM, Najman JM. Does maternal smoking during pregnancy have a direct effect on future offspring obesity? Evidence from a prospective birth cohort study. Am J Epidemiol. 2006;164:317–25.View ArticlePubMedGoogle Scholar
- Power C, Jefferis BJ. Fetal environment and subsequent obesity: a study of maternal smoking. Int J Epidemiol. 2002;31:413–9.View ArticlePubMedGoogle Scholar
- Toschke AM, Montgomery SM, Pfeiffer U, von Kries R. Early intrauterine exposure to tobaccoinhaled products and obesity. Am J Epidemiol. 2003;158:1068–74.View ArticlePubMedGoogle Scholar
- Slotkin TA. Fetal nicotine or cocaine exposure: which one is worse? J Pharmacol Exp Ther. 1998;285:931–45.PubMedGoogle Scholar
- Verhulst SL, Nelen V, Hond ED, Kiippen G, Beunckens C, Vael C, et al. Intrauterine exposure to environmental pollutants and body mass index during the first 3 yearsof life. Environ Health Perspect. 2009;117:122–6.View ArticlePubMedGoogle Scholar
- Smink A, Ribas-Fito N, Garcia R, Torrent M, Mendez MA, Grimalt JO, et al. Exposure to hexachlorobenzene during pregnancy increases the risk of overweight in children aged 6 years. Acta Paediatr. 2008;97:1465–9.View ArticlePubMedGoogle Scholar
- Chen A, Pennell M, Klebanoff M, et al. Maternal smoking during pregnancy in relation to child overweight: follow-up to age 8 years. Int J Epidemiol. 2006;35:121–30.View ArticlePubMedGoogle Scholar
- Syme C, Abrahamowicz M, Mahboubi A, Leonard GT, Perron M, Richer L, et al. Prenatal exposure to maternal cigarette smoking and accumulation of intra-abdominal fat during adolescence. Obesity. 2009;18(5):1021–5.View ArticlePubMedGoogle Scholar
- Buka SL, Goldstein JM, Spartos E, Tsuang MT. The retrospective measurement of prenatal and perinatal events: accuracy of maternal recall. Schizophr Res. 2004;71(2–3):417–26.View ArticlePubMedGoogle Scholar
- Githens PB, Glass CA, Sloan FA, Entman SS. Maternal recall and medical records: an examination of events during pregnancy, childbirth, and early infancy. Birth. 1993;20(3):136–41.View ArticlePubMedGoogle Scholar
- Yawn BP, Suman VJ, Jacobsen SJ. Maternal recall of distant pregnancy events. J Clin Epidemiol. 1998;51:399–405.View ArticlePubMedGoogle Scholar
- Villar J, Dorgan J, Menendez R, Bolaños L, Pareja G, Kestler E. Perinatal data reliability in a large teaching obstetric unit. Br J Obstet Gynaecol. 1998;95(9):841–8.View ArticleGoogle Scholar
- Krassas GE, Kelestimur F, Micic D, Tzotzas T, Konstandinidis T, Bougoulia M, et al. Self-reported prevalence of obesity among 20,329 adults from large territories of Greece, Serbia and Turkey. Hormones (Athens). 2003;2(1):49–54.View ArticleGoogle Scholar
- Manios Y. Design and descriptive results of the ‘Growth, Exercise and Nutrition Epidemiological Study In preSchoolers’: the GENESIS study. BMC Public Health. 2006;6:32.View ArticlePubMedPubMed CentralGoogle Scholar
- Villanueva EV. The validity of self-reported weight in US adults: a population based cross-sectional study. BMC Public Health. 2001;1:11.View ArticlePubMedPubMed CentralGoogle Scholar
- Manios Y, Grammatikaki E, Kondaki K, Ioannou E, Anastasiadou A, Birbilis M. The effect of maternal obesity on initiation and duration of breast-feeding in Greece: the GENESIS study. Public Health Nutr. 2009;12(04):517–24.View ArticlePubMedGoogle Scholar
- Brawarsky P, Stotland NE, Jackson RA, Fuentes-Afflick E, Escobar GJ, Rubashkin N, et al. Pre-pregnancy and pregnancy-related factors and the risk of excessive or inadequate gestational weight gain. Int J Gynaecol Obstet. 2005;91:125–31.View ArticlePubMedGoogle Scholar
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