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Logo of intjwhDove Medical PressThis ArticleSubscribeSubmit a ManuscriptSearchFollowDovepressInternational Journal of Women's Health
 
Int J Womens Health. 2013; 5: 389–398.
Published online 2013 July 3. doi:  10.2147/IJWH.S34042
PMCID: PMC3704399

Exercise in obese pregnant women: positive impacts and current perceptions

Abstract

Overweight and obesity have significant implications during pregnancy and childbirth. The objective of this review was to provide a comprehensive overview of the effect of physical activity on pregnancy outcomes, the change of physical activity during pregnancy, and women’s perception of being physically active during pregnancy, with a particular focus on women who are overweight or obese. Many studies have investigated the beneficial effect of exercise during pregnancy, including reduced risk of gestational diabetes, preeclampsia, and operative birth, in addition to improved cardiovascular function, overall fitness, psychological well-being, and mood stability. Benefits for the infant include reduced risks of prematurity and improved fetal growth, although there is more limited information about longer-term health benefits for both women and infants. The existing literature examining physical activity patterns during pregnancy has generally focused on women of all body mass index categories, consistently indicating a reduction in activity over the course of pregnancy. However, the available literature evaluating physical activity during pregnancy among women who are overweight or obese is more limited and contradictory. A number of studies identified barriers preventing women from being active during pregnancy, including pregnancy symptoms, lack of time, access to child care, and concerns about their safety and that of their unborn baby. Conversely, significant enablers included positive psychological feelings, family influence, and receiving advice from health professionals. Very few studies have provided insights about perceptions of being active during pregnancy in the overweight and obese population. There is a need for a detailed description of physical activity patterns during pregnancy in women who are overweight or obese, and more randomized trials evaluating exercise interventions for women who are overweight or obese, with a focus on clinical outcomes.

Keywords: pregnancy, exercise, physical activity, overweight, obesity

Introduction

Obesity is a significant contributor to chronic disease worldwide.1 Body size can be assessed using a variety of measures, including weight, height, and waist circumference. A widely utilized tool to assess overweight and obesity is body mass index (BMI). The World Health Organization (WHO) defines normal weight as a BMI of 18.5–24.9 kg/m2, overweight as a BMI of 25–29.9 kg/m2, and obesity as a BMI of 30 kg/m2 or greater.1 Obesity is further subcategorized into class I (30–34.9 kg/m2), II (35–39.9 kg/m2), and III (40 kg/m2 or higher).

The prevalence of overweight and obesity is escalating worldwide. Australian data indicate that 63.4% of Australian adults are overweight or obese, comprised of 35.0% overweight and 28.3% obese.2 It is predicted that by the year 2025, 7.2 million Australians will be obese.3 Worldwide figures are similar. In the US, 66% of the population is overweight or obese.4 The most recent data from the UK show similar trends, with the prevalence of obesity increasing significantly from 13% to 25% between 1993 and 2008.5 China’s National Health Survey also reported an increased prevalence of obesity, particularly among upper socioeconomic groups, with estimates that 11.44% of Chinese youth are overweight or obese.6

Overweight and obesity have significant implications during pregnancy and childbirth. In Australia, it was estimated that 34% of pregnant women were overweight or obese in 2002.7 More recent population data from South Australia indicate that approximately 50% of pregnant women are overweight or obese, including 10% who are severely or morbidly obese.8 Figures from the US and the UK are similar. In the US, between 1993 and 2003, the prevalence of maternal obesity increased from 13% to 22%,9 while there was a doubling in the UK between 1996 and 2006, with approximately 27.5% of pregnant women overweight, and a further 10.9% obese.10

Being overweight or obese may result in changes in hormone concentrations, adversely affecting reproductive health.11 Obesity increases estrogen concentrations and hence the risk of menstrual dysfunction, polycystic ovarian syndrome, and infertility.12,13 Both spontaneous rates of conception and outcomes following assisted reproductive techniques are poorer among women of high BMI when compared with women of normal BMI.12,13 The effect of obesity on risk of early pregnancy loss is less clear, with some studies reporting an increased risk of miscarriage, while others do not.13,14 It is well documented that even a moderate degree of weight loss can improve menstrual regularity and fertility among women who are overweight or obese.13

There are well-documented risks associated with obesity during pregnancy, the risks increasing with increasing maternal BMI.7,15,16 Well-recognized risks include gestational diabetes, hypertensive conditions (including preeclampsia), and preterm birth.7,15 There are also considerable risks for the infant, including an increased risk of perinatal death, congenital anomalies, shoulder dystocia, birth injuries, and macrosomia.7,15,17,18 The risks associated with overweight and obesity during pregnancy are summarized in Table 1.

Table 1
Risks associated with overweight and obesity during pregnancy

While the precise factors contributing to overweight and obesity are complex, these conditions essentially represent an imbalance between energy intake and energy expenditure. The total amount of energy an individual expends on a daily basis is a function of the amount of energy required to maintain basic bodily functions (resting energy expenditure), digest food eaten (thermic effect of food), maintain posture and spontaneous activity, and support voluntary bodily movement (physical activity).19 Reflecting its voluntary nature, physical activity is the most variable component of total daily energy expenditure. It comprises 20%–30% of total energy expenditure in sedentary adults, and the proportion is notably higher among active individuals.19 Domains of physical activity include leisure-time pursuits (exercise), occupation, transportation, self-care, volunteer work, nonexercise leisure-time activities, and domestic-related activity.19 Although each of these domains may have a significant influence on energy expended in physical activity and consequently total daily energy expenditure, until recently leisure-time physical activity was the focal point for research on energy expenditure in relation to obesity and public health efforts aimed at obesity treatment and prevention.19 The beneficial outcomes of being physically active are well recognized, including improving cardiovascular condition and glucose tolerance, building bone and muscle mass, and reducing risks of obesity and its complications.20,21

Physical activity has been identified as an important factor for healthy pregnancy in women of all weight ranges. Current Australian physical activity guidelines suggest adults, including pregnant women, be active with moderate-intensity exercise for 30 minutes on most days.22 Both the Royal College of Obstetricians and Gynaecologists and American College of Obstetricians and Gynecologists recommend that all pregnant women be encouraged to participate in exercise, with an aim of maintaining fitness throughout pregnancy.23,24 While previously inactive women and women with pregnancy complications may benefit from exercise, recommendations suggest evaluation on an individual basis.24 It is important to recognize that these activity guidelines for pregnant women are based on low-level evidence, and do not specifically address the issues facing women who are overweight or obese.

Research over the past 25 years has generated a large amount of information about exercise during pregnancy. However, the evidence has not been summarized to provide a full story about the benefits of antenatal exercise, current physical activity patterns during pregnancy, and women’s perception of exercise during pregnancy. The objective of this review was to provide a comprehensive overview of the effect of physical activity on pregnancy outcomes, the change of physical activity during pregnancy, and women’s perception of being physically active during pregnancy, with a particular focus on women who are overweight or obese.

Impact of exercise on pregnancy

Many studies have investigated the effect of exercise during pregnancy and maternal and neonatal health outcomes. A literature review was conducted to evaluate the effect of physical activity on pregnancy. The search identified articles published in PubMed and Scopus between 1990 and February 2013 using the following keywords: “exercise” or “physical activity” or “lifestyle” and “pregnancy”. The search resulted in 373 publications, of which the authors considered 81 after full-text review.

As outlined in Table 2, although studies utilized different research designs, a beneficial effect of exercise during pregnancy on maternal and neonatal health outcomes has been consistently identified. In particular, maternal health benefits include reduced risk of gestational diabetes,2527 preeclampsia,2830 and operative birth,31 in addition to improved cardiovascular function,32 overall fitness,33 psychological well-being, and mood stability.34,35 Benefits for the infant include reduced risks of prematurity36,37 and improved fetal growth,38 although there is more limited information about longer-term health benefits for both women and infants. However, these studies have limitations, including the inclusion of women of all BMI categories, failure to control for the effect of maternal BMI, and lack of standardization of methodology relating to assessment of physical activity, in addition to the limitations of specific study design. In addition, though a study that analyzed the intensity of physical activity during pregnancy suggested particularly beneficial effects from vigorous physical activity,30 it is difficult to draw conclusions, as studies (see Table 2) have utilized very different definitions43 to describe the intensity of exercise during pregnancy and are hence hard to compare.

Table 2
Studies describing exercise and maternal and neonatal health outcomes

There are three relevant Cochrane reviews relating to exercise in pregnant women.3941 Kramer and McDonald39 evaluated the role of exercise in pregnancy, while Ceysens et al40 and Han et al41 focused on exercise in women with gestational diabetes and the preventive effect of physical activity during pregnancy. Kramer and McDonald’s Cochrane review of aerobic exercise included women of all BMI categories during pregnancy, and included eleven randomized controlled studies, involving 1014 women.39 Outcome measurements included maternal physical fitness, infant anthropometric measures, and adverse maternal and infant birth outcomes. The included trials varied considerably in the nature of the intervention provided, the timing and duration of the intervention, and the assessment of compliance. The sample sizes of the individual studies were relatively small, and all were considered to have methodological flaws. While regular exercise was associated with maintained or improved physical fitness (defined as aerobic capacity, cardiopulmonary measures, and physical work capacity), the effect on clinical pregnancy outcomes was uncertain.

Ceysens and colleagues focused on exercise for women with gestational diabetes.40 The authors utilized data from four randomized controlled trials, involving a total of 114 pregnant women with gestational diabetes. The exercise programs generally included three 20- to 45-minute sessions per week of approximately 6 weeks’ duration. The meta-analysis did not identify a significant effect of exercise on measures of perinatal or maternal morbidity, although the available sample size was well underpowered to be able to detect differences in outcomes of clinical relevance. Similarly, Han and colleagues focused on the effect of physical activity in prevention of gestational diabetes.41 The findings indicated no significant differences in the incidence of gestational diabetes between women receiving additional exercise intervention and routine care.

In the overweight and obese pregnant population, several systematic reviews and meta-analyses have assessed the effect of antenatal exercise interventions on pregnancy outcomes.4244 These meta-analyses of randomized trials indicate that while antenatal exercise interventions do not appear to be associated with harm, the effect on limiting gestational weight gain was moderate (mean difference −0.36 kg, 95% confidence interval −0.64 to −0.09 kg, P = 0.008, I2 = 0%43; mean difference −0.72 kg, 95% confidence interval −1.2 to −0.25 kg, P = 0.003, I2 = 30%44). However, the available evidence is limited by small sample sizes and lack of consistent reporting of clinically relevant outcomes.

Change of physical activity during pregnancy

There is considerable literature indicating that pregnant women are less active than nonpregnant women, with activity declining over pregnancy.45,46 The existing literature examining physical activity patterns during pregnancy has generally focused on women of all BMI categories,4754 consistently indicating a reduction in activity over the course of pregnancy45 from early pregnancy to birth4952 (Table 3). This decline in activity was apparent across all categories and intensity of activities (household, leisure/exercise, work-related, and transportation).4952

Table 3
Studies describing physical activity pattern during pregnancy

The available literature evaluating physical activity during pregnancy among women who are overweight or obese is more limited. While some authors report an increase in activity from early to midpregnancy, followed by a decline in the third trimester,54 others report a constant reduction in activity across gestation53 (Table 3). Furthermore, there is little information reported in the literature evaluating the relationship between high maternal BMI and patterns of physical activity, in addition to the effect of gestational weight gain.

A prospective survey by Clarke and Gross46 reported that the decline in physical activity during pregnancy might be explained by a variety of social and psychological factors, as women perceived resting and relaxation as significantly more important than maintaining an active lifestyle. Major sources of information about physical activity advice included books, magazines, and family and friends, rather than health professionals. The findings of such studies indicate the importance of health professionals in improving the quantity and quality of health education about physical activity during pregnancy, including where possible the involvement of women’s family and friends.

Women’s perceptions of active lifestyle during pregnancy

While there are potential opportunities to implement interventions during pregnancy to improve health outcomes, success requires an understanding of women’s attitudes and perceptions, particularly their willingness to make behavioral changes.

While many interventions aim to promote healthy eating and active lifestyle in women who are overweight or obese during pregnancy,43,5557 it is constantly reported that adherence to interventions remains problematic. While a previous study has demonstrated that women’s attitudes toward weight-control interventions during pregnancy are generally positive,58 there is an increasing need to recognize and address individual psychological aspects and the impact they may have on successful behavioral change.59,60

A number of studies have investigated women’s perceptions of being active during pregnancy, identifying a number of enablers and barriers. As outlined in Table 4, these studies utilized a variety of tools, including self-reported questionnaires, telephone interviews with open-ended questions, focus groups, and semistructured face-to-face interviews, many utilizing mixed methods to gather both qualitative and quantitative data.46,6165 The most notable barriers identified preventing women from being active during pregnancy were pregnancy symptoms, lack of time, access to child care, and concerns about their safety and that of their unborn baby.

Table 4
Studies describing enablers and barriers of active lifestyle during pregnancy

Conversely, significant enablers included positive psychological feelings, family influence, and receiving advice from health professionals. Many of these studies are limited by their small sample size, and involved women of all BMI categories with no specific information available for pregnant women who were overweight or obese.

There are few studies that have explored the beliefs and experiences of exercise among women who were overweight or obese during pregnancy. Tovar et al’s study involved four focus groups66 to evaluate knowledge and beliefs regarding weight gain during pregnancy among a group of Hispanic women in the US. The results confirmed that while the majority of women felt negatively about weight gain, it was supported by family members in the belief that this would lead to a healthier baby. While women had awareness of the benefits of a healthy diet, traditional beliefs remained strong.

Weir et al evaluated beliefs about physical activity among overweight and obese pregnant women using semistructured interviews.67 Overall, women considered healthy eating of greater importance for maternal and infant health than participation in physical activity. Furthermore, while there was awareness that physical activity during pregnancy impacted on weight gain, women expressed a preference to defer weight management to the postnatal period.

Studies have identified a range of barriers preventing women from leading a healthier lifestyle during pregnancy, including physical, psychological, external, and environmental factors. In particular, a lack of advice was considered significant, with women expressing a lack of information relating to the benefits of physical activity on maternal and infant health. While most women who were overweight or obese recognized their weight as an issue, there was concern that health professionals in particular did not address women’s individual expectations.68

Our previous mixed-methods study in an overweight and obese pregnant population generated detailed information about women’s views of making healthy diet and lifestyle changes during pregnancy.69 Women completed questionnaires as well as a smaller number of face-to-face interviews, with results indicating that approximately half of women did not consider excessive gestational weight gain to be a concern during pregnancy. Although many women were aware that high BMI and high gestational weight gain were associated with adverse maternal health outcomes, knowledge of neonatal outcomes was less evident, as were perceived benefits of healthy change. While a range of barriers to change were identified, the strongest motivator reported was concern about maternal and neonatal health. Engaging in a healthy routine prior to conception, positive influences from family, and health professionals addressing individual expectations were all reported to be effective strategies to make healthy behavior changes during pregnancy.

The extant literature indicates that while women accept the occurrence of weight gain as a “normal” outcome of pregnancy,70 they report receiving a lack of and often inconsistent information from health professionals about high BMI and associated pregnancy risks, and about exercise during pregnancy.66,67,70 In contrast, advice from family relating to optimal gestational weight gain and physical activity was considered to be highly influential.66

Conclusion

Being overweight or obese during pregnancy is associated with an increased risk of maternal and infant health complications. While there are documented beneficial effects associated with exercise in pregnancy, recommendations to date are based on low-quality evidence and do not specifically address exercise in pregnancy for women who are overweight or obese. Furthermore, little is known about women’s perceptions of making healthy change during pregnancy. There is a need for a detailed description of physical activity patterns during pregnancy in women who are overweight or obese, and more randomized trials evaluating exercise interventions for women who are overweight or obese, with a focus on clinical outcomes. Further research also needs to identify effective strategies to increase physical activity among women who are overweight or obese during pregnancy, particularly at an individualized level.

Footnotes

Disclosure

The authors report no conflicts of interest in this work.

References

1. Obesity: preventing and managing the global epidemic. Report of a WHO consultation. World Health Organ Tech Rep Ser. 2000;894:i–xii. [No authors listed] [PubMed]
2. Australian Bureau of Statistics Overweight and obesity 2013. Available from: http://www.abs.gov.au/ausstats/abs@.nsf/Lookup/4338.0main+features82011-13Accessed April 27, 2013.
3. Diabetes Australia The Economic Costs of Obesity. Canberra: Diabetes Australia; 2006.
4. Flegal KM, Carroll MD, Ogden CL, Curtin LR. Prevalence and trends in obesity among US adults, 1999–2008. JAMA. 2010;303(3):235–241. [PubMed]
5. Health and Social Care Information Centre Health Survey for England – 2008: trend tables 2009. Available from: http://www.ic.nhs.uk/pubs/hse08trendsAccessed August 10, 2012.
6. Ji CY, Cheng TO. Epidemic increase in overweight and obesity in Chinese children from 1985 to 2005. Int J Cardiol. 2009;132(1):1–10. [PubMed]
7. Callaway LK, Prins JB, Chang AM, McIntyre HD. The prevalence and impact of overweight and obesity in an Australian obstetric population. Med J Aust. 2006;184(2):56–59. [PubMed]
8. Chan A, Scott J, Nguyen AM, Sage L. Pregnancy Outcome in South Australia 2008. Adelaide: Pregnancy Outcome Unit; 2009.
9. Kim SY, Dietz PM, England L, Morrow B, Callaghan WM. Trends in pre-pregnancy obesity in nine states, 1993–2003. Obesity (Silver Spring) 2007;15(4):986–993. [PubMed]
10. Sebire NJ, Jolly M, Harris JP, et al. Maternal obesity and pregnancy outcome: a study of 287,213 pregnancies in London. Int J Obes Relat Metab Disord. 2001;25(8):1175–1182. [PubMed]
11. Haslam DW, James WPT. Obesity. Lancet. 2005;366(9492):1197–1209. [PubMed]
12. Lake JK, Power C, Cole TJ. Women’s reproductive health: the role of body mass index in early and adult life. Int J Obes Relat Metab Disord. 1997;21(6):432–438. [PubMed]
13. Sarwer DB, Allison KC, Gibbons LM, Markowitz JT, Nelson DB. Pregnancy and obesity: a review and agenda for future research. J Womens Health (Larchmt) 2006;15(6):720–733. [PubMed]
14. Crosignani PG, Ragni G, Parazzini F, Wyssling H, Lombroso G, Perotti L. Anthropometric indicators and response to gonadotrophin for ovulation induction. Hum Reprod. 1994;9(3):420–423. [PubMed]
15. Doherty DA, Magann EF, Francis J, Morrison JC, Newnham JP. Pre-pregnancy body mass index and pregnancy outcomes. Int J Gynaecol Obstet. 2006;95(3):242–247. [PubMed]
16. Dodd JM, Grivell RM, Nguyen AM, Chan A, Robinson JS. Maternal and perinatal health outcomes by body mass index category. Aust N Z J Obstet Gynaecol. 2011;51(2):136–140. [PubMed]
17. Martinez-Frias ML, Frias JP, Bermejo E, Rodriguez-Pinilla E, Prieto L, Frias JL. Pre-gestational maternal body mass index predicts an increased risk of congenital malformations in infants of mothers with gestational diabetes. Diabet Med. 2005;22(6):775–781. [PubMed]
18. Henriksen T. Nutrition and pregnancy outcome. Nutr Rev. 2006;64(5 Pt 2):S19–S23. discussion S72–S91. [PubMed]
19. Harnack L, Schmitz K. The role of nutrition and physical activity in the obesity epidemic. In: Crawford D, Jeffery RW, editors. Obesity Prevention and Public Health. New York: Oxford University Press; 2005.
20. Clapp JF., 3rd Long-term outcome after exercising throughout pregnancy: fitness and cardiovascular risk. Am J Obstet Gynecol. 2008;199(5):489. e1–489. e6. [PMC free article] [PubMed]
21. Adamu B, Sani MU, Abdu A. Physical exercise and health: a review. Niger J Med. 2006;15(3):190–196. [PubMed]
22. Egger G, Donovan RJ, Giles-Corti B, Bull F, Swinburn B. Developing national physical activity guidelines for Australians. Aust N Z J Public Health. 2001;25(6):561–563. [PubMed]
23. Royal College of Obstetricians and Gynaecologists The growing trends in maternal obesity 2006. Available from: http://www.rcog.org.uk/news/growing-trends-maternal-obesityAccessed February 1, 2012.
24. Committee on Obstetric Practice ACOG committee opinion. Exercise during pregnancy and the postpartum period. Number 267, January 2002. American College of Obstetricians and Gynecologists. Int J Gynaecol Obstet. 2002;77(1):79–81. [PubMed]
25. Dempsey JC, Butler CL, Sorensen TK, et al. A case-control study of maternal recreational physical activity and risk of gestational diabetes mellitus. Diabetes Res Clin Pract. 2004;66(2):203–215. [PubMed]
26. Dempsey JC, Sorensen TK, Williams MA, 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):663–670. [PubMed]
27. Oken E, Ning Y, Rifas-Shiman SL, Radesky JS, Rich-Edwards JW, Gillman MW. Associations of physical activity and inactivity before and during pregnancy with glucose tolerance. Obstet Gynecol. 2006;108(5):1200–1207. [PMC free article] [PubMed]
28. Fortner RT, Pekow PS, Whitcomb BW, Sievert LL, Markenson G, Chasan-Taber L. Physical activity and hypertensive disorders of pregnancy among Hispanic women. Med Sci Sports Exerc. 2011;43(4):639–646. [PubMed]
29. Martin CL, Brunner Huber LR. Physical activity and hypertensive complications during pregnancy: findings from 2004 to 2006 North Carolina Pregnancy Risk Assessment Monitoring System. Birth. 2010;37(3):202–210. [PubMed]
30. Sorensen TK, Williams MA, Lee IM, Dashow EE, Thompson ML, Luthy DA. Recreational physical activity during pregnancy and risk of preeclampsia. Hypertension. 2003;41(6):1273–1280. [PubMed]
31. Melzer K, Schutz Y, Soehnchen N, et al. Effects of recommended levels of physical activity on pregnancy outcomes. Am J Obstet Gynecol. 2010;202(3):266. e1–266. e6. [PubMed]
32. Stutzman SS, Brown CA, Hains SM, et al. The effects of exercise conditioning in normal and overweight pregnant women on blood pressure and heart rate variability. Biol Res Nurs. 2010;12(2):137–148. [PubMed]
33. Lynch AM, McDonald S, Magann EF, et al. Effectiveness and safety of a structured swimming program in previously sedentary women during pregnancy. J Matern Fetal Neonatal Med. 2003;14(3):163–169. [PubMed]
34. Polman R, Kaiseler M, Borkoles E. Effect of a single bout of exercise on the mood of pregnant women. J Sports Med Phys Fitness. 2007;47(1):103–111. [PubMed]
35. Poudevigne MS, O’Connor PJ. Physical activity and mood during pregnancy. Med Sci Sports Exerc. 2005;37(8):1374–1380. [PubMed]
36. Evenson KR, Siega-Riz AM, Savitz DA, Leiferman JA, Thorp JM., Jr Vigorous leisure activity and pregnancy outcome. Epidemiology. 2002;13(6):653–659. [PubMed]
37. Hatch M, Levin B, Shu XO, Susser M. Maternal leisure-time exercise and timely delivery. Am J Public Health. 1998;88(10):1528–1533. [PubMed]
38. Clapp JF, 3rd, Kim H, Burciu B, Lopez B. Beginning regular exercise in early pregnancy: effect on fetoplacental growth. Am J Obstet Gynecol. 2000;183(6):1484–1488. [PubMed]
39. Kramer MS, McDonald SW. Aerobic exercise for women during pregnancy. Cochrane Database Syst Rev. 2006;3:CD000180. [PubMed]
40. Ceysens G, Rouiller D, Boulvain M. Exercise for diabetic pregnant women. Cochrane Database Syst Rev. 2006;3:CD004225. [PubMed]
41. Han S, Middleton P, Crowther CA. Exercise for pregnant women for preventing gestational diabetes mellitus. Cochrane Database Syst Rev. 2012;7:CD009021. [PubMed]
42. Campbell F, Johnson M, Messina J, Guillaume L, Goyder E. Behavioural interventions for weight management in pregnancy: a systematic review of quantitative and qualitative data. BMC Public Health. 2011;11:491. [PMC free article] [PubMed]
43. Sui Z, Grivell RM, Dodd JM. Antenatal exercise to improve outcomes in overweight or obese women: a systematic review. Acta Obstet Gynecol Scand. 2012;91(5):538–545. [PubMed]
44. Thangaratinam S, Rogozinska E, Jolly K, et al. Effects of interventions in pregnancy on maternal weight and obstetric outcomes: meta-analysis of randomised evidence. BMJ. 2012;344:e2088. [PMC free article] [PubMed]
45. Gaston A, Cramp A. Exercise during pregnancy: a review of patterns and determinants. J Sci Med Sport. 2011;14(4):299–305. [PubMed]
46. Clarke PE, Gross H. Women’s behaviour, beliefs and information sources about physical exercise in pregnancy. Midwifery. 2004;20(2):133–141. [PubMed]
47. Borodulin K, Evenson KR, Herring AH. Physical activity patterns during pregnancy through postpartum. BMC Womens Health. 2009;9:32. [PMC free article] [PubMed]
48. Duncombe D, Wertheim EH, Skouteris H, Paxton SJ, Kelly L. Factors related to exercise over the course of pregnancy including women’s beliefs about the safety of exercise during pregnancy. Midwifery. 2007;25(4):430–438. [PubMed]
49. Fell DB, Joseph KS, Armson BA, Dodds L. The impact of pregnancy on physical activity level. Matern Child Health J. 2009;13(5):597–603. [PubMed]
50. Mottola MF, Campbell MK. Activity patterns during pregnancy. Can J Appl Physiol. 2003;28(4):642–653. [PubMed]
51. Schmidt MD, Pekow P, Freedson PS, Markenson G, Chasan-Taber L. Physical activity patterns during pregnancy in a diverse population of women. J Womens Health (Larchmt) 2006;15(8):909–918. [PubMed]
52. Watson PE, McDonald BW. Activity levels in pregnant New Zealand women: relationship with socioeconomic factors, well-being, anthropometric measures, and birth outcome. Appl Physiol Nutr Metab. 2007;32(4):733–742. [PubMed]
53. McParlin C, Robson SC, Tennant PW, et al. Objectively measured physical activity during pregnancy: a study in obese and overweight women. BMC Pregnancy Childbirth. 2010;10:76. [PMC free article] [PubMed]
54. Renault K, Norgaard K, Andreasen KR, Secher NJ, Nilas L. Physical activity during pregnancy in obese and normal-weight women as assessed by pedometer. Acta Obstet Gynecol Scand. 2010;89(7):956–961. [PubMed]
55. Dodd JM, Grivell RM, Crowther CA, Robinson JS. Antenatal interventions for overweight or obese pregnant women: a systematic review of randomised trials. BJOG. 2010;117(11):1316–1326. [PubMed]
56. Tanentsapf I, Heitmann BL, Adegboye AR. Systematic review of clinical trials on dietary interventions to prevent excessive weight gain during pregnancy among normal weight, overweight and obese women. BMC Pregnancy Childbirth. 2011;11:81. [PMC free article] [PubMed]
57. Streuling I, Beyerlein A, von Kries R. Can gestational weight gain be modified by increasing physical activity and diet counseling? A meta-analysis of interventional trials. Am J Clin Nutr. 2010;92(4):678–687. [PubMed]
58. Kominiarek MA, Vonderheid S, Endres LK. Maternal obesity: do patients understand the risks? J Perinatol. 2010;30(7):452–458. [PubMed]
59. Gardner B, Wardle J, Poston L, Croker H. Changing diet and physical activity to reduce gestational weight gain: a meta-analysis. Obes Rev. 2011;12(7):e602–e620. [PubMed]
60. National Cancer Institute Theory at a Glance: A Guide for Health Promotion Practice. Bethesda (MD): National Cancer Institute; 2005.
61. Duncombe D, Skouteris H, Wertheim EH, Kelly L, Fraser V, Paxton SJ. Vigorous exercise and birth outcomes in a sample of recreational exercisers: a prospective study across pregnancy. Aust N Z J Obstet Gynaecol. 2006;46(4):288–292. [PubMed]
62. Evenson KR, Moos MK, Carrier K, Siega-Riz AM. Perceived barriers to physical activity among pregnant women. Matern Child Health J. 2009;13(3):364–375. [PMC free article] [PubMed]
63. Pereira MA, Rifas-Shiman SL, Kleinman KP, Rich-Edwards JW, Peterson KE, Gillman MW. Predictors of change in physical activity during and after pregnancy: Project Viva. Am J Prev Med. 2007;32(4):312–319. [PMC free article] [PubMed]
64. Symons Downs D, Hausenblas HA. Women’s exercise beliefs and behaviors during their pregnancy and postpartum. J Midwifery Womens Health. 2004;49(2):138–144. [PubMed]
65. Thornton PL, Kieffer EC, Salabarria-Pena Y, et al. Weight, diet, and physical activity-related beliefs and practices among pregnant and postpartum Latino women: the role of social support. Matern Child Health J. 2006;10(1):95–104. [PubMed]
66. Tovar A, Chasan-Taber L, Bermudez OI, Hyatt RR, Must A. Knowledge, attitudes, and beliefs regarding weight gain during pregnancy among Hispanic women. Matern Child Health J. 2010;14(6):938–949. [PMC free article] [PubMed]
67. Weir Z, Bush J, Robson SC, McParlin C, Rankin J, Bell R. Physical activity in pregnancy: a qualitative study of the beliefs of overweight and obese pregnant women. BMC Pregnancy Childbirth. 2010;10:18. [PMC free article] [PubMed]
68. Mills A, Schmied VA, Dahlen HG. ‘Get alongside us’, women’s experiences of being overweight and pregnant in Sydney, Australia. Matern Child Nutr. 2011 Dec 13; Epub. [PubMed]
69. Sui Z, Turnbull DA, Dodd JM. Overweight and obese women’s perceptions about making healthy change during pregnancy: a mixed method study. Matern Child Health J. 2012 Dec 22; Epub. [PubMed]
70. Smith D, Lavender T. The maternity experience for women with a body mass index ≥30 kg/m2: a meta-synthesis. BJOG. 2011;118(7):779–789. [PubMed]
71. Barakat R, Lucia A, Ruiz JR. Resistance exercise training during pregnancy and newborn’s birth size: a randomised controlled trial. Int J Obes (Lond) 2009;33(9):1048–1057. [PubMed]
72. Carmichael SL, Shaw GM, Neri E, Schaffer DM, Selvin S. Physical activity and risk of neural tube defects. Matern Child Health J. 2002;6(3):151–157. [PubMed]
73. de Barros MC, Lopes MA, Francisco RP, Sapienza AD, Zugaib M. Resistance exercise and glycemic control in women with gestational diabetes mellitus. Am J Obstet Gynecol. 2010;203(6):556. e1–556. e6. [PubMed]
74. Fortner RT, Pekow P, Solomon CG, Markenson G, Chasan-Taber L. Prepregnancy body mass index, gestational weight gain, and risk of hypertensive pregnancy among Latina women. Am J Obstet Gynecol. 2009;200(2):167. e161–167. e167. [PubMed]
75. Haakstad LA, Bo K. Exercise in pregnant women and birth weight: a randomized controlled trial. BMC Pregnancy Childbirth. 2011;11:66. [PMC free article] [PubMed]
76. Hui A, Back L, Ludwig S, et al. Lifestyle intervention on diet and exercise reduced excessive gestational weight gain in pregnant women under a randomised controlled trial. BJOG. 2012;119(1):70–77. [PubMed]
77. Ko CW, Napolitano PG, Lee SP, Schulte SD, Ciol MA, Beresford SA. Physical activity, maternal metabolic measures, and the incidence of gallbladder sludge or stones during pregnancy: a randomized trial. Am J Perinatol. 2013 Mar 1; Epub. [PubMed]
78. Latka M, Kline J, Hatch M. Exercise and spontaneous abortion of known karyotype. Epidemiology. 1999;10(1):73–75. [PubMed]
79. Mattran K, Mudd LM, Rudey RA, Kelly JS. Leisure-time physical activity during pregnancy and offspring size at 18 to 24 months. J Phys Act Health. 2011;8(5):655–662. [PubMed]
80. May LE, Glaros A, Yeh HW, Clapp JF, 3rd, Gustafson KM. Aerobic exercise during pregnancy influences fetal cardiac autonomic control of heart rate and heart rate variability. Early Hum Dev. 2010;86(4):213–217. [PubMed]
81. Nascimento S, Surita F, Parpinelli M, Siani S, Pinto ESJ. The effect of an antenatal physical exercise programme on maternal/perinatal outcomes and quality of life in overweight and obese pregnant women: a randomised clinical trial. BJOG. 2011;118(12):1455–1463. [PubMed]

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