|Year : 2019 | Volume
| Issue : 1 | Page : 2
Appropriate interventions for pregnant women with indicators of metabolic syndrome on pregnancy outcomes: A systematic review
Farideh Mohsenzadeh-ledari1, Ziba Taghizadeh2, Zahra Motaghi3, Afsaneh Keramat4, Mahmood Moosazadeh5, Ali Najafi6
1 Student Research Committee, School of Nursing and Midwifery, Shahroud University of Medical Sciences, Shahroud, Iran, Iran
2 Faculty Member of Nursing and Midwifery Research Center, Tehran University of Medical Sciences, Tehran, Iran
3 Department of Midwifery and Reproductive Health, School of Nursing and Midwifery, Shahroud University of Medical Sciences, Shahroud, Iran
4 Reproductive Studies and Women's Health Research Center, Shahroud University of Medical Sciences, Shahroud, Iran
5 Health Sciences Research Center, Addiction Institute, Mazandaran University of Medical Sciences, Sari, Iran
6 Shahroud University of Medical Sciences, Shahroud, Iran
|Date of Submission||23-Jan-2018|
|Date of Acceptance||07-Oct-2018|
|Date of Web Publication||15-Jan-2019|
Faculty Member of Nursing and Midwifery Research Center, Tehran University of Medical Sciences, Tehran
Source of Support: None, Conflict of Interest: None
Metabolic syndrome (MetS), a series of symptoms, including abdominal obesity, impaired glucose tolerance and insulin metabolism, hypertension, and dyslipidemia, is considered as the risk of developing cardiovascular disease and diabetes that can predispose a pregnant women to serious health problem, women in the developed as well as the developing countries. This study was aimed to investigate the effects of appropriate interventions on pregnant women with indicators of MetS to further improve the outcome of pregnancy. This systematic review was performed to extract articles of randomized controlled trials (RCT) on pregnant women with indicators of ( MetS) and focusing on physical activity, dietary or lifestyle interventions on maternal health or perinatal outcomes, with searching in the Web of Science, PubMed, CDSR, Scopus, and Google Scholar were investigated. Two researchers independently evaluated the quality of the studies, being presented in all the articles and ranked the studies as high/low quality; the level of evidence was based on the number of high-quality studies and the coordination of the obtained results. Then, 17 articles, which met the inclusion criteria, were selected; among these, 7 articles studied the physical activity, 3 articles reviewed diets, 6 probed the lifestyle interventions, and 1 article was on counseling. In general, evidence suggested how the physical activity and proper diet impacts on proper weight gain during pregnancy, prevents maternal complications, and improves the outcome of pregnancy. According to the results of this systematic review, proper interventions during pregnancy can have a positive effect on maternal weight gain and the general health condition of pregnant women with indicators of MetS.
Keywords: Interventions, metabolic syndrome, pregnancy outcomes, pregnant women
|How to cite this article:|
Mohsenzadeh-ledari F, Taghizadeh Z, Motaghi Z, Keramat A, Moosazadeh M, Najafi A. Appropriate interventions for pregnant women with indicators of metabolic syndrome on pregnancy outcomes: A systematic review. Int J Prev Med 2019;10:2
|How to cite this URL:|
Mohsenzadeh-ledari F, Taghizadeh Z, Motaghi Z, Keramat A, Moosazadeh M, Najafi A. Appropriate interventions for pregnant women with indicators of metabolic syndrome on pregnancy outcomes: A systematic review. Int J Prev Med [serial online] 2019 [cited 2020 Sep 30];10:2. Available from: http://www.ijpvmjournal.net/text.asp?2019/10/1/2/250296
| Introduction|| |
Being first identified by Reaven as a syndrome in 1988, metabolic syndrome (MetS) is a series of metabolic disorders, including abdominal obesity, impaired glucose tolerance and insulin metabolism, hypertension, and dyslipidemia.,, The most important health problems of the 21st century, this complicated and epidemic disorder, today, growingly effects the health of a large number of people in the developed and developing countries as well.
According to the predictions of World Health Organization (WHO), by 2020, chronic noncontagious diseases will have accounted for three quarters of deaths in developing countries, and MetS, which begins in childhood and is symptomatic in adulthood, will have been the risk factor for cardiovascular diseases and diabetes. Changes in dietary patterns, low physical activity, and smoking, so-called new world syndrome or lifestyle, are the main causes of the epidemic of noncontagious diseases in recent and future years., Reports indicate an upward trend for MetS in the population, especially women. According to statistics, about 25% of the US population – equivalent to 50 million individuals – is suffering from this syndrome. The first national study conducted on the prevalence of MetS in Iran in 2009 estimated the prevalence of this syndrome 34.7%, which is clearly higher than the average in the United States.
The prevalence of MetS in pregnant women varied from 3% to 42% in different studies based on the presence of preexisting syndrome components, age, and region.
Prepregnancy metabolic changes are not only the determinant of complications during pregnancy, after pregnancy, during postpartum life, but the reasons for inappropriate perinatal outcomes. Overweight women before pregnancy increases the risk of pregnancy complications; obesity turns out to be an independent risk factor for macrosomia cesarean section pregnancy-induced hypertension, preterm delivery intrauterine growth restriction, congenital malformation, intrauterine fetal death, etc., Pregnancy also creates an environment similar to MetS, including insulin resistance, increased blood sugar, triglycerides, and blood pressure; it is also considered as a potential accelerator for the risk of cardiovascular disease and diabetes. The emergence of MetS characteristics during pregnancy may also harm the fetus.
Diagnosis of MetS during pregnancy identifies women at high risk for cardiovascular and metabolic complications in later life and pregnant mothers potentially prone to pregnancy-related complications (preeclampsia, eclampsia, gestational diabetes mellitus [GDM], and coma). This characteristic makes it an appropriate opportunity to evaluate these adverse effects in perinatal period., MetS is a risk factor for preterm delivery and preeclampsia, leading to future cardiovascular disease in mothers.,,, This becomes even more important once we consider that women with MetS are at higher risk for GDM, and they are 30% more likely to have type 2 diabetes in the future.
Pregnant women are presented with risk factors for MetS at high risk of adverse maternal and neonatal outcomes such as abortion, preterm delivery, preeclampsia, gestational diabetes, gestational hypertension, preeclampsia postpartum hemorrhage, childbirth trauma, fetal abnormalities, low birth weight, intra uterine growth retardation, macrosomia stillbirth, and mortality.
Regarding perinatal complications in mother with MetS, infants have an increased probability of developing a MetS in late lactation period. An increase in these effects may not be limited to the first generation of the offspring, and in subsequent generations, metabolic problems may continue to persist.,,,,,,,
There are various strategies' measures to take to prevent obesity and MetS during nonpregnancy period, including increased physical activity, proper dietary habits, frequent and regular physician visits, and helping maintain the safe levels of blood pressure, cholesterol, and blood glucose. The feasible treatment of syndrome would be to change the wrong lifestyle, via increasing physical activity, casting excess weight, reducing daily stress, quitting smoking, and medication treatment before pregnancy, to name a few. The beneficial effects in reducing the risk factors of MetS such as blood pressure, lipid, and lipoprotein have been observed in individuals., Although some interventions such as fostering proper diet and physical activity have a positive effect on preventing weight gain during pregnancy, there are currently limited information on effective interventions that can be used to improve maternal, fetal, and neonatal health outcomes.
Therefore, this study aimed to conduct a systematic review using high-quality interventional studies in order to identify appropriate interventions in pregnant women with indicators of MetS during pregnancy and use these interventions to improve the pregnancy outcomes. Reducing maternal complications such as gestational diabetes, preeclampsia, etc., promoting the health of fetuses and newborns includes the Apgar score, the weight, and so on.
| Methods|| |
This systematic review was in accordance with the criteria presented by the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement.
Data collection was performed by searching in articles using four main electronic databases of Cochrane Library (search CDSR), Web of Science, PubMed, Scopus, and Google Scholar.
Using the Mesh terms, following relevant keywords and combination of words were used in systematic searches: metabolic syndrome; indicators of metabolic syndrome; obesity or overweight; lipids; triglycerides; high-density cholesterol; low-density cholesterol; diabetes; fasting blood glucose; waist circumference; blood pressure; maternal outcomes; pregnancy complications; gestational hypertension; gestational diabetes; maternal weight gain; preeclampsia; cesarean section; postpartum hemorrhage; induction of labor; neonatal outcomes; macrosomia; birth weight; gestational age; hyperbilirubinemia; hypoglycemia; Apgar score; gestational age; preterm delivery; intervention; physical activity; exercise; exercise therapy; lifestyle; early intervention (training); health education; patient education; health promotion; counseling; nutrition; diet; carbohydrate limitation; Mediterranean diet; fat limitation; weight loss; diet therapy; clinical trial. The searches were performed with no time limitations; they were confined to human studies and clinical trials published until August 2017. Systematic searches were performed on the main databases and targeted searches were performed on other databases. All sources were evaluated for increased sensitivity. The search results were categorized and evaluated using Endnote software.
Criteria inclusion and exclusion for studies
All studies in English or Persian with on time limitations, encompassing randomized controlled trials that evaluated and measured the effects of different interventions in pregnant women with indicators of MetS and the outcome of pregnancy were included. Systematic reviews, before-and-after-pregnancy intervention studies, and observational studies were excluded. In this study, the population, intervention, comparison, outcome, study design system was designed which is expanded as follows: P = pregnant women with risk factors for MetS, I = intervention involving physical activity, lifestyle, counseling, and diet, C = pregnant women with metabolic risk factors with standard health care, O = outcome of pregnancy, S = interventional studies and randomized clinical trial.
Two researchers separately carried out electronic searching, picked up a study, and applied proper methodology for evaluation, separately selected relevant studies according to entry criteria. Screening was performed after narrowing the search strategy and duplication removal. Inappropriate articles were identified during the review of titles, abstracts, and full text.
Data collection process
The two researchers independently extracted the data. In the first step, the title and the abstract of each article was carefully scrutinized. In the next step, studies were evaluated in terms of methodology quality and appropriate entry criteria by two researchers independently without considering the results [Table 1] and [Table 2].
|Table 1: A summary randomized trials on pregnant women with risk factors for metabolic syndrome|
Click here to view
|Table 2: A summary of the features of the interventions used in the reviewed studies|
Click here to view
Quality evaluation of studies
The methodology quality of studies was evaluated by two researchers on the basis of how they minimized bias and error in their work. Studies were classified based on the PRISMA,, Jadad, and Cochrane Library guidelines as high or low quality. For example, objectives, the comparison of the control and intervention group, the population studied, and information about the results were reported in high-quality studies. The quality validation and evaluation of the studies included random method, concealment and random allocation, blindness, incomplete results, selective result reporting, and complete follow-up. The selection of the results was agreed upon by both researchers based on an assessment of the scales in [Table 3]. In this assessment, the scores ≥3 were considered as high quality and scores ≤2 as poor quality., Further coordination, later, helped resolve the controversies between the authors.
The extracted data for each study included the primary outcome of weight gain during pregnancy and secondary outcomes such as maternal and neonatal complications, gestational diabetes, preeclampsia, gestational hypertension, preterm delivery, cesarean delivery, neonatal macrosomia (>4000 g); birth weight; intrauterine growth retardation; and low birth weight ≤2500 g, and their Apgar scores are summarized in [Table 4] and [Table 5].
The study was approved by the Ethics Committee of the Shahroud University of Medical Sciences No. IR.SHMU.REC.1395.123. The permission to use articles from all authors was not applicable.
| Results|| |
The evaluation process is shown in [Figure 1], and the selected articles and the results of review are summarized in [Table 3] and [Table 4]. A total number of 1043 studies were evaluated by searching in electronic sources. About 1027 studies were excluded by endnote in the first phase after the duplication review. Out of 210 studies, 193 studies were excluded due to lack of inclusion criteria and 17 papers' randomized clinical trials (on 5475 pregnant women) were matched and evaluated; among these, 7 articles studied the physical activity (1499), 3 articles reviewed diets (3089), 6 probed the lifestyle interventions (1125), and 1 article was on counseling (122). In general, evidence suggested how the physical activity and proper diet impacts on proper weight-gain during pregnancy, prevents maternal complications, and improves the outcome of pregnancy.
The main reasons for the exclusion were participants with normal/healthy BMI, nonpregnant women, women who needed extraweight in pregnancy, irrelevant results, irrelevant goals, irrelevant interventions, unreliable full article, irrelevant design, nonclinical trials, and articles published in languages other than English or Persian. Characteristics of the studies are described in [Table 2]. All of these studies were designed as a clinical trial.,,,,,,,,,,,,,,,, All the final 17 studies were conducted in developed countries: 5 in Spain, 2 in the United States, 2 in Belgium and 2 in United Kingdom, 1 in Brazil, 1 in Canada, 1 in Turkey, 1 in Denmark, 1 in Australia, and 1 in Norway. They were all inclusive of seven physical activities ranging from 30 to 90–120 min/session;,,,,,, six cases of lifestyle,,,,,, three cases of diets,,, and one case of consultation [Figure 1]. In all studies, prepregnancy interventions were preferably done in the first trimester of pregnancy. Dietary interventions included a balanced diet such as carbohydrates, protein, and fat, and routine interventions based on physical activity, including light intensity exercises, weight bearing exercises, and moderate walking for 30 min. Combined interventions included counseling sessions, training on the potential benefits of a good diet and physical activity, and feedback on weight gain in pregnancy. Combined interventions were used as behavioral modification techniques to improve women's insight on their emotional control of eating and preventing their eating habits. The number of physical activity or exercise sessions was between 2 and 3 times/week and the duration of exercise per session varied from 30 to 120 min. The total number of program sessions was 24–85 weeks. The sample size in the collected clinical trials featured 5475 participants; each study had 60–1555 participants. In the studies of intervention and control groups, the maternal age and BMI were matched. The main goal of most studies was primarily to reduce and control overweight and to enhance the pregnancy outcome. Seventeen clinical trials were evaluated in terms of quality according to [Table 5]. For all cited trials, the control group received no intervention and only received standard care for pregnancy. The evaluated results included birth weight, infant birth, Apgar score, gestational diabetes, type of delivery, maternal overweight, labor duration, gestational hypertension, and preeclampsia. Considering the significant differences in the provided interventions and the type of risk factors, it was not appropriate to combine the results for meta-analysis. In 17 clinical trials, the effect of interventions on increasing maternal weight was compared in mothers with metabolic risk factors and women in control group. The lowest overweight was observed in the intervention group ranging from 4.1 ± 5.0 kg weight gains in the intervention group to 14.5 ± 3.9 kg in control group, which was statistically significant (P ≤ 0.001). Interventions had no negative effect on birth weight. The birth weight in the intervention group ranged from the lowest level of 3.203 ± 464 g to the highest in the control group 3678 ± 583 g. The two groups did not have any significant difference in this regard (P ≥ 0.05). Other neonatal outcomes in two groups were different, though this difference was not statistically significant.
According to systematic review done, the most appropriate intervention for pregnant women with MetS indicators is the combination of physical activity and diet that is provided by an obstetrician's with nutritionist assistance. According to the American College of Obstetricians and Gynecologists, guidelines for physical activity during pregnancy through increasing walking and developing a more active lifestyle and the dietary by the American Dietetic Association are summarized in [Table 6].
| Discussion|| |
The main objective of this study was to collect and present articles on the interventions related to pregnant women with indicators of MetS on the pregnancy outcome. The results of this systematic review showed that there is currently limited information available on clinical recommendations for effective interventions for counseling in terms of physical activity, diet, and lifestyle for pregnant women with MetS; that's why there are comprehensive articles defining the possible, thus far unresolved, complications associated with indicators of MetS during pregnancy and childbirth, also there is limited information available related to effective interventions that may be implemented to improve maternal, fetal, and infant health outcomes. Exercise in pregnancy affects health outcomes for the woman through improved cardiovascular function and restriction of weight gain, with a documented reduction in the risk of preterm birth, and favorable effects on labor and birth. This is an important consideration because excessive gestational weight gain is associated with higher postpartum weight retention, which in turn increases the risk of cardiovascular disease and other chronic conditions later in life. Excessive gestational weight gain also raises the risk of developing other obstetric complications such as gestational diabetes or hypertension,,, which are considered cardiovascular disease risk factors in the course of pregnancy, during delivery and in the postpartum period.,
The current study with a high sample size (5475 pregnant women with a metabolic syndrome index) of the Articles clinical trial was conducted. Based on the results of the present study, dietary and lifestyle interventions are effective in reducing overweight during pregnancy without any complication. Compared to physical activity and combined approach, dietary interventions had the highest weight loss results during pregnancy. Interventions also led to a significant reduction in maternal complications (preeclampsia, gestational diabetes, preterm delivery, pregnancy overweight, gestational hypertension) and improved pregnancy outcomes. The results were not, however, statistically significant. In addition, there was a lack of information on the impact of interventions on neonatal outcomes. Interventions had less effect on the implications related to fetal weight and other neonatal diseases and deaths. The number of newborns weighing more than 4000 g in the intervention group was lower than the control group. This is an important consideration given the negative outcomes associated with macrosomia, that is, higher incidence of postpartum hemorrhage, cesarean sections, shoulder dystocia, birth traumas, or the risk of developing obesity and diabetes mellitus later in life, and there was no evidence, showing that interventions would reduce the rate of cesarean or induced delivery.
Most published studies zoom in on the effects of dietary, physical activity, and lifestyle interventions on pregnancy outcomes (maternal, neonatal, and embryo) in pregnant women with indicators of MetS. There was evidence of undesirable dietary effects during pregnancy, but usually found in studies with severe diets for weight loss, or for those who consumed food with high or low glycemic index. It was also found that weight loss during pregnancy was not associated with increased number of infants who were small based on gestational age. The findings suggested that multifaceted intervention is adopted, compared with stand-alone dietary advice, exercise modification, or behavioral strategies during pregnancy that were more effective on limiting pregnancy weight gain and reducing maternal complications such as preeclampsia, gestational diabetes, gestational hypertension, and preterm delivery. Besides, one of the main concerns of mothers was recognized to be the impact of dietary interventions and lifestyle changes on child's weight. There was no evidence in terms of any relationship between these interventions with adverse maternal or fetal outcomes during pregnancy and childbirth.
| Conclusion|| |
Thus far, there have been no precise recommendations to manage MetS during pregnancy in order to improve pregnancy outcomes. Our overall results indicated that physical activity, proper diet, and lifestyle changes can improve the outcome of pregnancy in pregnant women with risk factors for MetS. Amongst these, safe and effective dietary interventions can be potentially more effective than physical activity. Unfortunately, the available data are not sufficient to determine the important risks or other potential benefits of interventions for the mother or baby. There are also no studies on the cost–benefits of a health-care system potent enough to implement interventions to reduce pregnancy complications. However, there is a need to conduct more randomized controlled clinical trials on this issue.
No potential conflicts of interest directly relevant to this content of this article were reported. The present study was supported by Shahroud University of Medical Sciences as a Ph.D. Thesis. We hereby acknowledge the research deputy for grant no. 9577 and to Dr. Evangeline Foronda for the English editing and proofreading. The attempt and hardworking of researchers of previous studies used in our study are highly appreciated.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Reaven GM. Role of insulin resistance in human disease. Diabetes 1988;37:1595-607.
Grundy SM, Brewer HB Jr, Cleeman JI, Smith SC Jr, Lenfant C. Definition of metabolic syndrome: Report of the National Heart, Lung, and Blood Institute/American Heart Association conference on scientific issues related to definition. Arterioscler Thromb Vasc Biol 2004;24:e13-8.
Hamidreza Barahimi MD AEP FR, Akbar Hasanzadeh PhD, Omolbanin Kafeshani MSc. Association of dietary pattern and metabolic syndrome in 15- to 49-years-old women. J Isfahan Med School 2015;33:70-81.
Azizi F, Hadaegh F, Khalili D, Esteghamati A, Hosseinpanah F, Delavari A, et al
. Appropriate definition of metabolic syndrome among Iranian adults: Report of the Iranian National Committee of Obesity. Arch Iran Med 2010;13:426-8.
Hajian-Tilaki K. Metabolic syndrome and its associated risk factors in Iranian adults: A systematic review. Caspian J Intern Med 2015;6:51-61.
Organization WH. Cancer control: Knowledge into action: WHO guide for effective programmes: World Health Organization, 2007.
Villanueva Sagrado Ma, Ullrich A, World Health O. Cancer control: Knowledge into action: WHO guide for effective programmes. Module 2, Module 2. Geneva: WHO; 2007.
Li R, Li W, Lun Z, Zhang H, Sun Z, Kanu JS, et al
. Prevalence of metabolic syndrome in mainland china: A meta-analysis of published studies. BMC Public Health 2016;16:296
Vahid S, Sahar G, Mohammadtaghi S, Maryam E, Shirin TJ, Ali E. The frequency of metabolic syndrome among female patients admitted in psychiatry ward. Med J Mashhad Univ Med Sci 2012;54:230-7.
Delavari A, Forouzanfar MH, Alikhani S, Sharifian A, Kelishadi R. First nationwide study of the prevalence of the metabolic syndrome and optimal cutoff points of waist circumference in the Middle East. Diabetes Care 2009;32:1092-7.
dos Prazeres Tavares H, Arantes MA, Tavares SBMP, Abbade JF, Calderon IdMP, Rudge MVC. Metabolic syndrome and pregnancy, its prevalence, obstetrical and newborns complications. Open J Obstet Gynecol 2015;5:618-25.
Bartha JL, Marín-Segura P, González-González NL, Wagner F, Aguilar-Diosdado M, Hervias-Vivancos B. Ultrasound evaluation of visceral fat and metabolic risk factors during early pregnancy. Obesity 2007;15:2233-9.
Gluckman PD, Hanson MA, Cooper C, Thornburg KL. Effect of in utero
and early-life conditions on adult health and disease. N Engl J Med 2008;359:61-73.
Bhowmik B, Afsana F, Siddiquee T, Munir SB, Sheikh F, Wright E, et al
. Comparison of the prevalence of metabolic syndrome and its association with diabetes and cardiovascular disease in the rural population of Bangladesh using the modified National Cholesterol Education Program Expert Panel Adult Treatment Panel III and International Diabetes Federation definitions. J Diabetes Investig 2015;6:280-8.
Bartha JL, González-Bugatto F, Fernández-Macías R, González-González NL, Comino-Delgado R, Hervías-Vivancos B. Metabolic syndrome in normal and complicated pregnancies. Eur J Obstet Gynecol Reprod Biol 2008;137:178-84.
Isezuo SA, Ekele BA. Comparison of metabolic syndrome variables among pregnant women with and without eclampsia. J Natl Med Assoc 2008;100:1059-62.
Chatzi L, Plana E, Daraki V, Karakosta P, Alegkakis D, Tsatsanis C, et al
. Metabolic syndrome in early pregnancy and risk of preterm birth. Am J Epidemiol 2009;170:829-36.
Hooijschuur MC, Ghossein-Doha C, Al-Nasiry S, Spaanderman ME. Maternal metabolic syndrome, preeclampsia, and small for gestational age infancy. Am J Obstet Gynecol 2015;213:370.e1-7.
Kianpour M, Norozi S, Bahadoran P, Azadbakht L. The relationship between metabolic syndrome criteria and preeclampsia in primigravid women. Iran J Nurs Midwifery Res 2015;20:263-8.
Rodie VA, Freeman DJ, Sattar N, Greer IA. Pre-eclampsia and cardiovascular disease: Metabolic syndrome of pregnancy? Atherosclerosis 2004;175:189-202.
Young B, Hacker M, Rana S. Pre-eclampsia and risk of cardiovascular disease and cancer in later life: Systematic review and meta-analysis. Hypertens Pregnancy 2012;31:50-8.
Negrato CA, Jovanovic L, Tambascia MA, Calderon IdMP, Geloneze B, Dias A, et al
. Mild gestational hyperglycaemia as a risk factor for metabolic syndrome in pregnancy and adverse perinatal outcomes. Diabetes Metab Res Rev 2008;24:324-30.
Ryckman KK, Borowski KS, Parikh NI, Saftlas AF. Pregnancy complications and the risk of metabolic syndrome for the offspring. Curr Cardiovasc Risk Rep 2013;7:217-23.
Gonzalez-Bulnes A, Ovilo C, Astiz S. Transgenerational inheritance in the offspring of pregnant women with metabolic syndrome. Curr Pharm Biotechnol 2014;15:13-23.
Catov JM, Bodnar LM, Kip KE, Hubel C, Ness RB, Harger G, et al
. Early pregnancy lipid concentrations and spontaneous preterm birth. Am J Obstet Gynecol 2007;197:610.e1-7.
Sattar N, Greer IA. Pregnancy complications and maternal cardiovascular risk: Opportunities for intervention and screening? BMJ 2002;325:157-60.
Hou R-L, Jin W-Y, Chen X-Y, Jin Y, Wang X-M, Shao J, et al
. Cord blood C-peptide, insulin, HbA1c, and lipids levels in small-and large-for-gestational-age newborns. Med Sci Monit 2014;20:2097-105.
Maleki F, Sayehmiri F, Kiani F, Nasiri S. Metabolic syndrome prevalence in Iran: A systematic review and meta-analysis. J Kermanshah Univ Med Sci 2014;18:242-50.
Saeed S, Nasab MM, tarahi MJ. Prevalence of overweight and obesity in 64-25 year-old population of Khorramabad city, 1385. J Diabet Lipid Disord 2009;8:167-76.
Moher D, Shamseer L, Clarke M, Ghersi D, Liberati A, Petticrew M, et al
. Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015 statement. Syst Rev 2015;4:1.
Liberati A, Altman DG, Tetzlaff J, Mulrow C, Gotzsche PC, Ioannidis JP, et al
. The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate healthcare interventions: Explanation and elaboration. BMJ (Clinical research ed). 2009;339:b2700.
Higgins JP, Green S. Cochrane handbook for systematic reviews of interventions. John Wiley & Sons; 2011.
Lei JH, Liu LR, Wei Q, Yan SB, Song TR, Lin FS, et al
. Systematic review and meta-analysis of the survival outcomes of first-line treatment options in high-risk prostate cancer. Sci Rep 2015;5:7713.
Halpern S, Douglas M. Jadad scale for reporting randomized controlled trials. Evidence-Based Obstet Anesth 2005:237-8.
Guelinckx I, Devlieger R, Mullie P, Vansant G. Effect of lifestyle intervention on dietary habits, physical activity, and gestational weight gain in obese pregnant women: A randomized controlled trial. Am J Clin Nutr 2010;91:373-80.
de Oliveria Melo AS, Silva JLP, Tavares JS, Barros VO, Leite DF, Amorim MM. Effect of a physical exercise program during pregnancy on uteroplacental and fetal blood flow and fetal growth: A randomized controlled trial. Obstet Gynecol 2012;120:302-10.
Barakat R, Pelaez M, Lopez C, Montejo R, Coteron J. Exercise during pregnancy reduces the rate of cesarean and instrumental deliveries: Results of a randomized controlled trial. J Matern Fetal Neonat Med 2012;25:2372-6.
Adamo KB, Ferraro ZM, Goldfield G, Keely E, Stacey D, Hadjiyannakis S, et al
. The Maternal Obesity Management (MOM) Trial Protocol: A lifestyle intervention during pregnancy to minimize downstream obesity. Contemp Clin Trials 2013;35:87-96.
Bogaerts A, Devlieger R, Nuyts E, Witters I, Gyselaers W, Van den Bergh B. Effects of lifestyle intervention in obese pregnant women on gestational weight gain and mental health: A randomized controlled trial. Int J Obes 2013;37:814-21.
Deveer R, Deveer M, Akbaba Et, Engin-Ustun Y, Aydogan P, Celikkaya H, et al
. The effect of diet on pregnancy outcomes among pregnant with abnormal glucose challenge test. Eur Rev Med Pharmacol Sci 2013;17:1258-61.
Hawkins M, Hosker M, Marcus B, Rosal MC, Braun B, Stanek E, et al
. A pregnancy lifestyle intervention to prevent gestational diabetes risk factors in overweight Hispanic women: A feasibility randomized controlled trial. Diabet Med 2015;32:108-15.
Vinter C, Jørgensen J, Ovesen P, Beck-Nielsen H, Skytthe A, Jensen D. Metabolic effects of lifestyle intervention in obese pregnant women. Results from the randomized controlled trial 'Lifestyle in Pregnancy'(LiP). Diabet Med 2014;31:1323-30.
Vesco KK, Karanja N, King JC, Gillman MW, Leo MC, Perrin N, et al
. Efficacy of a group-based dietary intervention for limiting gestational weight gain among obese women: A randomized trial. Obesity 2014;22:1989-96.
Poston L, Bell R, Croker H, Flynn AC, Godfrey KM, Goff L, et al
. Effect of a behavioural intervention in obese pregnant women (the UPBEAT study): A multicentre, randomised controlled trial. Lancet Diabet Endocrinol 2015;3:767-77.
Haakstad LA, Edvardsen E, Bø K. Effect of regular exercise on blood pressure in normotensive pregnant women. A randomized controlled trial. Hypertens pregnancy. 2016;35:170-80.
Barakat R, Pelaez M, Cordero Y, Perales M, Lopez C, Coteron J, et al
. Exercise during pregnancy protects against hypertension and macrosomia: Randomized clinical trial. Am J Obstet Gynecol 2016;214:649.e1-8.
Aparicio VA, Ocón O, Padilla-Vinuesa C, Soriano-Maldonado A, Romero-Gallardo L, Borges-Cósic M, et al
. Effects of supervised aerobic and strength training in overweight and grade I obese pregnant women on maternal and foetal health markers: The GESTAFIT randomized controlled trial. BMC Pregnancy Childbirth 2016;16:290.
Ryu A, Kim TH, Park YJ, Enkhbold T. Re: Self-weighing and simple dietary advice for overweight and obese pregnant women to reduce obstetric complications without impact on quality of life: A randomised controlled trial. BJOG 2017;124:697-8.
Al Wattar BH, Dodds J, Placzek A, Spyreli E, Moore A, Hooper R, et al
. Effect of simple, targeted diet in pregnant women with metabolic risk factors on maternal and fetal outcomes (ESTEEM): Study protocol for a pragmatic multicentre randomised trial. BMJ Open 2016;6:e013495.
Tinius RA, Cahill AG, Cade WT. Impact of physical activity during pregnancy on obstetric outcomes in obese women. Journal Sports Med Phys Fitness 2017;57:652-9.
Barakat R, Pelaez M, Lopez C, Lucia A, Ruiz JR. Exercise during pregnancy and gestational diabetes-related adverse effects: A randomised controlled trial. Br J Sports Med 2013;47:630-6.
Yazdy MM, Liu S, Mitchell AA, Werler MM. Maternal dietary glycemic intake and the risk of neural tube defects. Am J Epidemiol 2009;171:407-14.
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]