Title Diet and physical activity interventions to prevent excessive gestational weight gain : a systematic review
Author(s) Wang, Xingyue;
王星月Citation
Issued Date 2014
URL http://hdl.handle.net/10722/206966
Rights Creative Commons: Attribution 3.0 Hong Kong License
Abstract of Project titled
“Diet and physical activity interventions to prevent excessive gestational weight gain: A systematic review”
Submitted by
Wang Xingyue
for the Degree of Master of Public Health at The University of Hong Kong
in August 2014
Background
Excessive gestational weight gain (GWG) poses significant risk for maternal and neonatal health. Various guidelines have recommended healthy diets and enhancing physical activity during pregnancy to prevent excessive GWG. However, results of intervention studies are inconsistent in the developed countries, and there are no official guidelines and few interventions for GWG in China. This paper aims to review and synthesize relevant studies on diet and physical activity interventions to prevent excessive GWG so that practical suggestions can be provided to public health authorities in China.
Methods
This systematic review was performed using PubMed, Google and Google Scholar to search all relevant studies in English and randomised controlled trials (RCTs) that investigated diet and physical activity interventions to limit excessive GWG up to May 2014. The quality of included studies was assessed using CONSORT statement and
JADAD scale.
Results
Nine studies describing diet and physical activity interventions to prevent excessive GWG were incorporated in the systematic review. Overall, the contents of interventions were diverse, which consisted of one-to-one counselling, and community-based physical activity interventions. Weekly mailed newsletters and supportive telephone calls were used as assistive tools to remind pregnant women of limiting excessive GWG. Seven studies showed less weight gain in pregnant women receiving the intervention, of which four studies demonstrated a reduction in excessive GWG in women with varying body mass index (BMI) spanning the normal, overweight and obese categories, while three studies reported a reduction of excessive GWG only in normal weight women and obese women need to be paid attention in the future.
Conclusions
The effectiveness of diet and physical interventions to limit excessive GWG may not be confirmed because of limited quality or sample size of intervention studies. However, studies have demonstrated reduction of excessive GWG during pregnancy, in addition to persistent healthy behaviours following such interventions during pregnancy.
Further meta-analyses of RCTs studies should be done to confirm the effectiveness of such interventions among Chinese women.
Key words: gestational weight gain, obesity, diet, physical activity.
Diet and physical activity interventions to prevent excessive gestational weight gain: A systematic review
by
Wang Xingyue
A Project submitted in fulfilment of the requirements for the Degree of Master of Public Health
at The University of Hong Kong
August 2014
Declaration
I declare that the Project and the research work thereof represent my own work, except where due acknowledgement is made, and that it has not been previously included in a thesis, dissertation or report submitted to this University or to any other institution for a degree, diploma or other qualifications.
Signed
Wang Xingyue
Acknowledgements
I would like to thank my supervisor Dr. Leung, Yue Yan June for her invaluable advice and comments on this project. Without her patience and continuous feedbacks, this project would not be made possible.
Many thanks for my professors, tutors and classmates of the School of Public Health for their insights and assistance in the Master of Public Health (MPH) program at the University of Hong Kong.
Finally, I wish to thank my family for their encouragement and support through all my MPH years. I feel blessed to have all the people acknowledged.
Contents
Declaration ... i
Acknowledgements ...ii
Tables and Figures...iv
Abbreviation... v
Chapter 1 Background ...1
1.1 Excessive gestational weight gain (GWG) ...1
1.2 Current guidelines for GWG...2
1.3 Determinants of excessive GWG...3
1.4 Interventions for preventing excessive GWG ...3
1.5 Aim and objective...4
Chapter 2 Methods ...5
2.1 Overview...5
2.2 Search strategy...5
2.3 Inclusion criteria ...6
2.4 Exclusion criteria...6
2.5 Quality assessment of RCTs...7
Chapter 3 Results... 8
3.1 Selection of studies...8
3.2 Summary of included studies...9
3.3 Summary of setting and participants...10
3.4 Description of interventions...10
3. 5 Reduction of GWG ...12
3.6 Secondary outcomes of interventions...13
3.7 Assessment of quality of studies...14
Chapter 4 Discussion ...19
4.1 Main findings...19
4.2 Strengths and limitations...21
4.3 Policy and recommendations...22
Chapter 5 Conclusion...23
Tables and Figures
List 1.
JADAD quality rating studies...7
Figure 1
Flow diagram of literature search...9
Table 1
Characteristics of included studies...15
Table 2
Assessment for quality of studies...18
Abbreviations
ACOG BMI CI
CONSORT GWG IOM JADAD Li MI NICE OR PRISMA
RCOG RCT UK US WHO
American Congress of Obstetricians and Gynaecologists, United States Body mass index
Confidence interval
Consolidated standards of reporting trials Gestational weight gain
Institute of Medicine, the United States
The JADAD scale is named after Alejandro Jadad-Bechara Low intensity
Moderate intensity
National Institute for Health and Care Excellence, the United Kingdom Odds ratio
Preferred reporting items for systematic reviews and meta-analyses recommendation
Royal College of Obstetricians and Gynaecologists, United Kingdom Randomized controlled trial
United Kingdom United States
World Health Organization
Chapter 1 Background
1.1 Excessive gestational weight gain (GWG)
The increasing prevalence of overweight or obesity among women of childbearing age has been one of the most serious health problems that scientists and practitioners faced in the past thirty years[1, 2]. According to the World Health Organization (WHO) standard for BMI categories, in the United Kingdom (UK), about half of women at childbearing age are either overweight (BMI 25.0-29.9 kg/m2) or obese (BMI ≥ 30.0 kg/m2), with 18% of women becoming obese during pregnancy[1]. In the United States (US), 25% of women at 20 to 39 years old are overweight and 29% are obese[3]. In addition, obesity is associated with maternal deaths, with more than half of maternal deaths during pregnancy or delivery due to excessive GWG[4]. Therefore, it is time to take interventions to address excessive GWG in pregnancy.
According to the Institute of Medicine (IOM) guidelines, the definition of “excessive GWG” is inappropriately large weight gain during pregnancy, and recommendations of GWG are different according to the pre-pregnancy BMI[1, 2]. The more the weight gain exceeds recommendations, the higher the risk of complications in pregnancy[5- 7]. Excessive GWG is linked to several adverse outcomes during pregnancy, including gestational diabetes, gestational hypertension, prematurity, preeclampsia, and caesarean delivery[8]. Not only are excessive GWG responsible for complications during pregnancy, it is also linked with high weight retention after pregnancy, long-term obesity, and cardiovascular disease[9]. Importantly, GWG also influences childhood outcomes[1]. Potential adverse outcomes in the child include infant macrosomia, late foetal death, birth defects, and childhood obesity[10-15].
1.2 Current guidelines for GWG
The commonly used recommendations of GWG include National Institute for Health and Care Excellence (NICE), the American Congress of Obstetricians and Gynaecologists (ACOG) and Royal College of Obstetricians and Gynaecologists (RCOG)[16-18]. Most studies on GWG adopted standard weight gain during pregnancy according to the recommendation provided by the IOM[1, 2]. In 1990, the IOM formulated specific recommendations for GWG based on pre-pregnancy BMI, and the IOM improved the guidelines of GWG corresponding to the worldwide epidemic of obesity in 2009[1, 2]. Moreover, the IOM 2009 stressed the importance of healthy lifestyle interventions in pregnancy to prevent adverse outcomes for both women and children[1].
The IOM guidelines 2009 recommend that normal weight women (BMI 18.5-24.9 kg/m2) gain 11.5-16 kg (25-35 lbs.) during pregnancy, underweight women (BMI <
18.5 kg/m2) gain 12.5-18 kg (28-40 lbs.), overweight women (BMI 25.0-29.9 kg/m2) gain 7-11.5 kg (15-25 lbs.), and that obese women (BMI ≥ 30.0 kg/m2) gain 5-9 kg (11-20 lbs.)[1]. The new guidelines have two features compared with those released in 1990. Firstly, they use the ranges provided by WHO for different BMI categories instead of the previous ones, which was based on the categories of the Metropolitan Life Insurance tables. Secondly, the improved guidelines contain more detailed and narrower ranges of recommended GWG for overweight and obese women[1].
So far, median weekly weight gain during pregnancy is often used as a result indicator of GWG for Chinese women, because there is a lack of official guideline of GWG in China. Studies indicated different distributions of pre-pregnancy BMI between Chinese and Caucasian women, therefore it is difficult to apply western guidelines for GWG into Chinese, such as the IOM guidelines[3, 19].
1.3 Determinants of excessive GWG
The total amount of GWG is determined by various factors. The biological and behavioural factors of excessive GWG include high pre-pregnancy BMI, physical activity, gestational age, primiparity, dietary practice (dietary intake, dieting, and food insecurity), and not following recommended guidelines for GWG[20, 21].
Psychological factors associated with excessive GWG include higher depressive, anxiety symptoms, body image dissatisfaction, lower self-esteem, greater body image dissatisfaction and misperceived pre-pregnancy size[1, 7].
1.4 Interventions for preventing excessive GWG
Through this review, I wanted to examine and synthesize behavioural interventions to limit excessive GWG for women of all weight ranges. Many articles have reviewed the impacts of lifestyle interventions to prevention GWG issues only for overweight or obese women but not for women of normal weight [4, 22]. Furthermore, evidence shows that up to 40% of women whose pre-pregnancy BMI are normal have excessive weight gain during pregnancy, and women whose pre-pregnancy BMI are underweight also have risks of excessive GWG and high weight retention[7, 23-25].
Interventions to prevent GWG include dietary interventions, physical activity and both of them. According to NICE recommendations, dietary intake and physical activity during pregnancy are two main modifiable aspects influencing maternal and neonatal health outcomes[26]. My review therefore focuses on interventions aimed at both diet and physical activity for women of all weight ranges to prevent GWG.
Pregnancy is a time of physical and physiological transitions for women. It is a significant beginning of a life stage, during which women would pay more attention to their diet and weight, because they are also the needs of their children. Therefore, pregnancy is an important time to address weight gain in order to achieve more positive, effective and persistent outcomes compared to the postpartum period[27].
1.5 Aim and objective
The aim of this systematic review is to identify and synthesize the effectiveness of interventions on diet and physical activity for limiting excessive GWG from all countries, so that relevant suggestions on GWG guidelines and prevention interventions can be provided to the public health system in China. The objectives of this review are to compare and synthesize the different interventions on diet and physical activity to prevent excessive GWG for different pre-pregnancy BMI groups, and to evaluate the quality of these studies.
Chapter 2 Methods
2.1 Overview
The preferred reporting items for systematic reviews and meta-analyses recommendation (PRISMA) guideline for reporting systematic reviews of public health interventions was regarded as a methodological model for this systematic review. Consolidated standards of reporting trials (CONSORT 2010) guidelines for reporting parallel group randomized trials and the JADAD scale were used to guide the assessment of methodological quality of all randomized controlled trials (RCTs) [28, 29].
2.2 Search strategy
A literature search was conducted on PubMed based on a combination of key words, including (pregnancy OR gestation) AND (intervention OR ((diet OR energy intake) AND (exercise OR physical activity))) AND (weight gain OR weight change). A search filter was applied to limit the search to RCTs and humans published in English. In addition, Google Scholar and Google were also used to locate relevant grey literature including guidelines and reports by authoritative public health agencies up to May 2014.
After excluding duplicated articles, articles were also removed from the review if they were not relevant, had no full text, or did not fulfil the inclusion criteria, based on screening of their titles and/or abstracts. In case of uncertainty, the full text was reviewed to determine relevance. I also went through the bibliography of relevant GWG guidelines and the cited papers in the retrieved articles to locate relevant articles.
2.3 Inclusion criteria
The inclusion criteria applied were the following:
Types of participants: Women above 18 years old with singleton pregnancies were
included. Women who were of normal weight (BMI 18.5-24.9 kg/m2), overweight (25-29.9 kg/m2) or obese (BMI≥ 30 kg/m2) were included in the review.Types of intervention: The interventions included should be designed to
encourage pregnant women to obtain GWG within the recommendations, including both diet and physical activity. Any intervention lacking either component would be excluded from this systematic review.Types of outcomes: The difference in GWG in the intervention and comparison
groups was considered as the primary outcome to detect diet and physical activity intervention to prevent GWG.Types of study: Only RCTs were included.
2.4 Exclusion criteria
Letters, editorials or other publications that only provide authors’ opinions were excluded in the systematic review. Secondary sources such as guidelines or WHO publications were regarded as complementary information but were not included in the literature review. Studies aimed at other purposes, such as improving or managing a specific disease during pregnancy (e.g. gestational diabetes) were also excluded. Observational studies were excluded, as RCTs provide the best level of evidence that determines cause-effect relationships between risk factors and outcome.
2.5 Quality assessment of RCTs
In this study, the CONSORT Statement, including the 25-item checklist, was used to guide the review of each trial’s design, analysis and interpretation, and to evaluate the effectiveness of its outcomes[28]. All included studies were graded from 0 to 5 points applying the JADAD scale to quantitatively compare the quality of RCTs [29].
The JADAD scale of 3 basic items and 2 additional points are as following:
List 1. JADAD quality rating studies[29]
JADAD Scale items
1. Was the study described as randomized?
2. Was the study described as double-blinded?
3. Was there a description of withdrawals and drop out?
4. Was the method to generate the sequence of randomization described and was it appropriate?
5. Was the method of double blinding described and was it appropriate?
Scoring the items: the range of a given score is 1- to 1, and there are no in-between
marks.“1” point means “Yes” & “Appropriate”
“0” point means “No”
“-1”point means “Yes” & “Inappropriate”
Chapter 3 Results
3.1 Selection of studies
An initial search using the combination of key words identified 633 potentially relevant studies. After further exclusion of 134 articles, 164 papers were screened after limiting the search to RCTs, humans, and the English language. Of these, 30 articles were included for in-depth evaluation. As a consequence, 21 were excluded, as 17 papers met exclusion criteria, which were studies that did not aim at modifying diet and physical activity during pregnancy as the primary objective;
while the other 4 had no full text. After reviewing the full text, 9 articles were finally included in the literature review. The process of the literature search is shown in Figure 1 below.
Figure 1- Flow diagram of literature search
3.2 Summary of included studies
The nine included studies were all RCTs published from 2002 to 2013[5, 7-9, 30-34].
In addition to preventing excessive GWGs, the secondary outcomes of diet and physical activity interventions including health behaviour change and postpartum weight retention were also evaluated in the different studies. An overview of the details of different interventions is presented in Table 1.
3.3 Summary of setting and participants
Search terms
PubMed, Google and Google Scholar
Screening-RCTs research
164 potentially relevant articlesidentified
In-depth evaluation
30 potentially relevant articles included
Excluded: 134 articles were not relevant, were not in English or have no full text
Final literature review 9 articles included
Excluded: 21 articles met exclusion criteria or did not contain original empirical data
from the Netherlands, and one from Germany[5, 7-9, 30-34]. All nine studies covered varying ranges of pre-pregnancy BMI, pregnancies below 26 weeks of gestation, and women above 18 years old.
Each of the included studies adopted the IOM 1990 or 2009 guidelines for GWG, with the exception of Hui et al. (2006) who adopted the Canadian guidelines for weight gain, and Huang et al. who used GWG as recommended by the Department of Health in Taiwan[7, 32]. The two guidelines had different GWG suggestions based on local pre-pregnancy BMI compared to IOM guideline.
In total, 1,666 participants (907 in the intervention group, 759 in the control group) were recruited to the nine studies. Sample sizes ranged from 52 to 401 (mean of 185 participants per study). The participants were recruited from hospitals, obstetric clinics or community nurse-managed centres. Potential participants were excluded from the studies if they had comorbid medical conditions (e.g. gestational diabetes or gestational hypertension), were below 18 years old, had multi-foetal pregnancy or took part in other interventions at the same time. The nature of the study was that participants could not be blinded to the type of intervention, because participants were clearly aware of the diet and physical activity intervention which they took part in. Participants covered different socioeconomic positions, and no significant baseline differences in age, pre-pregnancy BMI, income and education were detected between the intervention and comparison groups. Four studies included women of different races, including African American, Asian, White, Hispanic and Latina[5, 8, 9, 33].
3.4 Description of interventions
The contents of interventions were complex, which consisted of one-to-one counselling and community-based physical activity interventions based on the
telephone calls were regarded as assistive tools to remind pregnant women of preventing excessive GWG. For the control groups, all the pregnant women would receive universal prenatal care.
One-to-one counselling was the core method for participants to prevent excessive GWG on diet. The healthcare provider would provide an individualized meal plan for participants, including food choices, frequencies, portion sizes and the distributions of energy intake. The goal for intake of food would be made for the participants at an early stage of the intervention. The Food Choice Map (FCM) was adopted in two studies, which is a computerized dietary interview tool to assist dieticians to assess nutrition intake at an early stage of the program for participants[32, 33]. FCM software analysed total energy and nutrition in daily intake, as well as GWG according to information obtained during the interview. Dieticians could then provide a much more accurate and personalized gestational meal plan to every participant.
Compared with dietary interventions, physical activity interventions were much more diverse. Most studies had written concrete and positive physical activity plans, except Althuizen et al.[34]. Five studies adopted one-to-one counselling on physical activity, including enhancing walking, stretching, floor aerobics and strength exercises; and healthcare providers also made a minimum goal for participants[5, 7- 9, 30]. Ruchat et al. stratified the intervention group into two parts to detect the effectiveness of a supervised low intensity (LI) (i.e. minimum intensity physical activity needed to obtain health benefits for limiting excessive GWG) versus a moderate intensity (MI) weight-bearing physical activity only in women of normal weight[30]. It is also the only study mandating participants to attend at least one physical activity section per week at the laboratory to monitor the adherence rate and record the GWG weekly.
Hui et al. did two diet and physical activity community-based interventions to limit
exercise[32, 33]. Instead of one-to-one counselling on physical activity, Hui et al.
held group sessions and home-based physical activities. Weekly group-sessions were held in the gymnasium of the community centre provided to the participants.
Participants had flexible options for joining daytime or evening physical activity sessions, and physical activity instruction videos were provided to participants to help them do exercise at home.
Besides the counselling and community-based interventions, weekly mailed newsletters, supportive telephone calls were used as assistive tools to remind pregnant women of preventing excessive GWG. Some studies emphasized the significance of psychological factors in the form of counselling or support[7, 8, 30, 31]. These studies tried to identify and address emotional cognitive and situational barriers that may hinder behaviour change[1]. Only Huang et al.[7] included participants’ psychosocial factors in the outcome measurement, including assessment of bodies’ image and depression and perceived social support.
3. 5 Reduction of GWG
GWG reduction was regarded as primary outcome indicators that detected the effectiveness of intervention about diet and physical activity between the intervention and control groups. The results of the nine included studies were inconsistent.
Four studies reported less GWG for women of all ranges of weight [7, 9, 31, 32].
Among the remaining five studies, three studies only evaluated GWG for normal weight women[5, 8, 30]. In Ruchat et al., where participants included only normal- weight women (BMI=18.5-24.9 kg/m2), the two intervention groups (LI & MI) gained less weight than the control group (LI, P=0.01; MI, P=0.003)[30]. Polley et al.
and Phelan et al. reported less weight gain for normal weight women (BMI=18.5-
women (BMI=30 kg/m2 or above)[5, 8]. The remaining two studies showed insignificant reduction in excessive GWG[33, 34].
3.6 Secondary outcomes of interventions
In the diet and physical activity interventions, besides preventing excessive GWG, the studies also measured other outcomes in pregnancy.
Four interventions reported on health behaviour changes, which referred to whether pregnant women could sustain diet and physical activity until the postpartum period[5, 7, 31, 33]. Huang et al. indicated that women who received the intervention showed higher active healthy lifestyle behaviour both in diet and physical activity after delivery six months longer than the comparison group[7].
Kathrin et al. reported that the intervention group had a lower energy intake than the comparison group (P<0.05), however, there was no difference in physical activity in the intervention and control groups[31]. Hui et al. showed that the level of physical activity in the intervention group was higher than those in the control group (P<0.01), but it had no effect on diet[33]. Polley et al. reported that there was no health behaviour difference between the intervention and comparison groups[5].
The effectiveness of interventions on decreasing postpartum weight retention was evaluated by six studies [5, 7, 8, 30, 31, 34]. The outcomes of weight retention were inconsistent. Polley et al., Huang et al. and Phelan et al. found that diet and physical activity interventions increased the percentage of normal weight and overweight/obese women who returned to their pre-pregnancy weight or below by six months after delivery (P<0.05)[5, 7, 8]. Kathrin et al., Ruchat et al. and Althuizen et al. reported that maternal weight retention was similar between the intervention and control groups[30, 31, 34].
Only Huang et al. evaluated psychosocial outcomes, including self-efficacy, depression, body image, and social support, which were effective in preventing
excessive GWG for participants in the intervention group compared with the control group[7].
3.7 Assessment of quality of studies
According to the CONSORT guideline 2010 and JADAD scale, Table 2 shows the methodological quality of the nine studies. Seven of the nine studies were considered to be high quality trials, adopting the standard of JADAD score greater than 2[35].
The seven high-score studies all correctly described the randomization procedure (awarded 1 point)[7-9, 30-32, 34]. Kathrin et al. performed randomization at the cluster level[31]. Most studies reported their procedure of randomization, using a computer-generated allocation[9, 31, 32, 34], randomized/block procedure[8, 30], and pre-stratification [5, 8, 9, 33, 34]. All nine studies described the dropout rate and the reasons. As mentioned before, the nature of the trial meant that participants were not blinded to the type of intervention. In this assessment, I only assessed the blinding to healthcare providers. Only two of nine studies reported blinding to healthcare providers with adequate description of the process [7, 8].
Four studies correctly described the allocation concealment (marked with “+”)[8, 9, 31, 32], three of which used concealed opaque envelopes[8, 9, 32]. In Kathrin et al.
study, a lab technician who did not attend this trial performed the allocation[31].
Table 1 Characteristics of included studies Study Participants Interventions
Methods Contents
Definition of GWG
Results
Polley et al.
2002 USA
120 pregnant women at< 20 weeks gestation BMI: 19.8-29.0
Race: Black & White
One-to-one counselling on dietary and physical activity. Newsletters were mailed biweekly. Supportive telephone calls. Regular clinic visits for weight monitoring.
Diet: limiting high-fat foods;
individualized meal plan; making available calorie goal.
Physical activity: enhancing walking; forming more active lifestyle habits.
GWG based on IOM 1990 guidelines.
Intervention group had a lower prevalence of Normal Weight women exceeding
recommendation (33% vs. 58%; P<
0.05); Non-significant effect of excessive GWG among overweight women (59% vs. 32%; P=0.09).
Hui et al.
2006 Canada
52 pregnant women at <26 weeks gestation BMI: all ranges
Race: Aboriginal & Asian.
Community session physical activity was held in gym in a community centre, 3-5 times per week for 30 to 45 min.
One-to-one counselling on nutrition. The Food Choice Map (FCM) was used as a tool for assessment.
Diet: recommended healthy dietary in frequency, pattern and energy intake.
Physical activity: floor aerobics, stretching and strength exercises 45min/session.
GWG based on Canadian guideline for healthy weight
No difference of excessive GWG between intervention and control group (21% vs. 33%; P=0.07).
Asbee et al.
2009 USA
100 pregnant women at 6-16 weeks gestation BMI: <40
Race: African American, Asian, White, Hispanic and other
One-to-one counselling on diet and physical activity. Instructed to engage in moderate intensity physical activity.
Regular weight monitoring with routine obstetrical appointment.
Diet: instructed a patient-focused goal of caloric intake: a 40%
carbohydrate, 30% protein, and 30% fat fashion.
Physical activity: moderate intensity physical activity at least three times per week.
GWG based on IOM 1990 guidelines.
Intervention group gained less weight than the control group (13.2± 5.7 kg vs. 16.4 ± 7.1 kg;
P=0.01).
Huang et al. 2009 Taiwan
189 pregnant women at 16 weeks gestation BMI: 16.60-36.90 Race: Chinese women
One-to-one counselling on dietary and physical activity. Regular supervising weight gain with each clinic visit.
Prepared GWG suggestion brochures were provided
Diet: food choice, food components, calorie intake, portion size, and personal plan.
Physical activity: physical activity categories, recommended energy expenditure on physical activity.
GWG based on
Department of Health in Taiwan.
Intervention group gained less weight than control group (14.27 kg vs. 16.22 kg; P<0.001). All psychological outcomes were better in intervention group women (P < 0.001).
Phelan et al.
2011 USA
401 pregnant women at 10-16 weeks gestation.
BMI: 19.8-40.0
One-to-one counselling on dietary and physical activity. Weekly mailed materials were regarded as supervised tool. Supportive telephone calls. The Fit for Delivery Intervention was
developed.
Diet: limiting high fat foods, calorie goal during pregnancy was 20kcal/kg.
Physical activity: enhancing physical activity, the goal was 30min of walking most day of the week.
GWG based on IOM 1990 guidelines.
Intervention group had a lower percentage of Normal Weight women exceeding suggestion than control group (OR: 0.38; 95% CI:
0.02, 0.87; P= 0.003);
No effect among overweight or obese women (OR: 1.4; 95% CI:
0.70, 2.7; P=0.33).
Hui et al.
2011 Canada
190 pregnant women at < 26 weeks gestation.
BMI: all ranges
A community-based physical activity program in gym in community. A physical activity instruction video was provided. One-to-one diet counselling based on Food Choice Map results.
Diet: monitoring the more healthy transformation in dietary.
Physical activity: walking, mild- to-moderate aerobic, swimming, and stretching. 3-5 times per week of moderate physical activity for 30 - 45 min per session.
GWG based on IOM 2009 guidelines.
Intervention group gained less weight than control group (35.3%
vs. 54.5%; chi-square 7.10; 95% CI 0.47-0.90, P=0.008).
Ruchat et al. 2012 USA
118 pregnant women at 16-20 weeks gestation.
BMI: 18.5-24.9
One-to-one counselling on dietary and physical activity. Pregnancy women in intervention group were required to come to the lab at least one time for physical activity session per week.
Diet: an individualised gestational meal plan; the goal of total daily energy intake is 8360KJ/d, meeting daily micronutrient.
Physical activity: 30 min of walking per session.
GWG based on IOM 2009 guidelines.
Intervention group had less weight gain (control group 18.3± 5.3 kg, LI: 15.3 ± 2.9 kg, P=0.01; MI: 14.9±
3.8kg, P=0.003).
No differences between the intervention groups LI and MI (P=0.72).
Althuizen et al. 2012 Netherland s
246 pregnant women at 15 weeks gestation BMI: all ranges
One-to-one counselling on dietary and lifestyle for 5 times during pregnancy;
supportive telephone calls; regular clinic visit for weight monitoring.
N/A GWG based
on IOM 2009 guidelines.
No effect on the difference in percentage of weight gain exceeding recommendations between intervention and control group (OR=0.92; 95% CI: 0.48- 1.77).
Kathrin et al. 2013 Germany
250 pregnant women at below 18 weeks gestation
BMI: ≥ 18.5 Race: German
One-to-one counselling on dietary, physical activity and weight monitoring.
Making behavioural plan based on the baseline situation and individual preference.
Diet: limiting intake of high fat foods, and eating more fruits, vegetables and grain products.
Physical activity: 30 min per session at a proper heart-rate zone, like swimming, cycling.
GWG based on IOM 2009 guidelines.
Intervention group had less weight gain than the control group (38%
vs. 60%; OR: 0.5; 95% CI: 0.3-0.9).
Table 2 Assessment for quality of studies[29]
Item 1: Described as randomized study (0/+1 point) Item 2: Described as double-blinded study (0/+1 point) Item 3: Described withdrawal and dropouts (0/+1 point)
Item 4: Appropriate/inappropriate randomization procedure (+1/-1 point) Item 5: Appropriate/inappropriate double-blinding measures (+1/-1 point)
Study
1
2
Item 3
4
5
JADAD Score
Allocation Concealment
Polley 1
0 1 0 0 2-
Hui
(2006)1 0 1 0 0 2
-
Asbee 1
0 1 1 0 3+
Huang 1
1 1 0 1 4-
Phelan 1
1 1 1 1 5+
Hui
(2011)1 0 1 1 0 3
+
Ruchat 1
0 1 1 0 3-
Althuizen
1 0 1 1 0 3-
Kathrin 1
0 1 1 0 3+
Chapter 4 Discussion
4.1 Main findings
This systematic review included nine RCTs on diet and physical activity interventions to prevent excessive GWG. The effectiveness of included interventions was inconsistent. Only four of the nine included studies report a reduction in excessive GWG over the normal, overweight and obese categories[7-9, 31]. And three studies reported a decrease in GWG in normal weight women [5, 8, 30]. Phelan et al. and Kathrin et al. are the highest efficacy of RCTs among the nine included studies [8, 31].
According to NICE recommendations, food intake and physical activity during pregnancy are the two main modifiable determinants influencing maternal and infant outcomes[26]. However, the mechanisms by which lifestyle behaviour change leads to reduction of GWG are still unclear. Therefore meta-analyses of RCTs are needed to demonstrate whether excessive GWG can be prevented by diet and physical activity interventions.
Second, according to analysis of the studies, the total amount of GWG had a close relationship with pre-pregnancy BMI [5, 9, 27, 30, 31]. In two studies, diet and physical activity interventions were only effective in normal weight women[5, 30].
Higher pre-pregnancy BMI might increase the risk for excessive GWG (P<0.0001). In addition, high gestational age at delivery was also related to excessive GWG[8].
Therefore it may be important to offer pre-conception education for pregnant women.
Third, community-based intervention on physical activity was a novelty, which may be feasible for pregnant women in the community [32, 33]. Apart from maintaining a healthy weight during pregnancy, the feasibility of interventions for mother and
infant is another concern we need to take into consideration. Physical activity interventions for pregnancy are difficult to maintain due to physiological and psychological changes during pregnancy, especially in the late third trimester. The feasibility of recommendations on preventing excessive GWG still need to be verified.
Fourth, postpartum weight retention and health behaviour change are inconsistent in the nine included studies. Even though studies have positive effects for women on returning to their pre-pregnancy weight or below, we cannot conclude that diet and physical activity intervention to limit GWG is beneficial to maintain postpartum weight. This question needs to be verified by further research.
In addition, combining outcomes and quality assessment, Phelan et al. and Kathrin et al. are the highest quality RCTs among the nine included studies[8, 31]. Their interventions showed reduction in GWG compared with control group. Hui et al.
(2006) and Althuizen et al. had no effect on preventing excessive GWG, relatively low scores in quality assessment and smaller sample sizes[33, 34]. This highlights the need for well-designed RCTs with sufficient power in order to clarify the effectiveness of diet and physical activity interventions. In 2010, Hui et al. did a larger (80% power) and higher quality RCT (JADAD Score: 3) than before, which found that the intervention group had less GWG than the comparison group[32, 33].
The included studies are not without limitation. For sample size, Polley et al. and Asbee et al. had no specified power calculation in the study[5, 9]. And two studies’
underpowered sample size may limit the effectiveness of diet and physical activity interventions to prevent GWG[33, 34]. All nine studies relied on self-reported pre- pregnancy weight and dietary records, which might have been underestimated by overweight and obese women, leading to possible misclassification of some overweight or obese women as normal weight. However, bias was minimal if
being in an intervention could result in an overestimation of the intervention effect.
Lastly, there is the potential for healthy volunteer bias. Women who are healthier in general tend to participate in research. Further investigation of diet and physical activity interventions for pregnant women with comorbid medical conditions is needed.
4.2 Strengths and limitations
Several strengths in this systematic review are identified. First, I have only included RCTs in my evaluation, because they give the highest level of evidence for effectiveness. Secondly, JADAD scale and allocation concealment are taken into consideration in quality assessment to address the limitation of CONSORT 2010.
CONSORT 2010 is used to guide the review of each trial’s design, analysis and interpretation and the validity of its outcomes, but it is not proper for construction of a “quality score”[28]. Thirdly, I have included studies spanning women of all pre- pregnancy BMI categories including normal, overweight and obese. Last, my included studies’ participants consist of multiple ethnicities (e.g. European, Aboriginal, Asian, African, American).
This review is not without inherent limitations. Firstly, the included studies are published only in English. Secondly, because of the incomplete and unclear description of some interventions and outcome of the studies, a meta-analysis could not be done. Thirdly, this study reviewed the interventions to prevent excessive GWG and did not explore postpartum weight management. As mentioned before, Polley et al. found an association (r=0.89, P<0.001) between excessive GWG and postpartum weight retention[5]. Fourthly, most included studies are done in Western populations, which may have different dietary patterns from the Chinese population. Therefore, we should be cautious in generalizing diet and physical activity interventions from Western populations to China. In addition, the effect of effect on GWG may not be completely attributable to interventions due to the
heterogeneity of the interventions. Last but not least, the author alone was involved in the process of the systematic review, which might lead to bias in the selection, and assessment of quality of studies.
4.3 Policy and recommendations
Through this review, I have found that most studies were performed in developed countries. So far, the IOM, NICE, RCOG, ACOG and some public health agencies in developed countries have provided recommendations on weight management during pregnancy. In less-developed countries, especially Asia, women commonly have a lower pre-pregnancy BMI and/or a smaller GWG than in developed countries[36]. Therefore, it is necessary and useful to verify whether the effectiveness of diet and physical activity intervention for excessive GWG in terms of IOM guidelines is fit for women in developing countries. However, this systematic review should provide some useful lifestyle recommendations to prevent excessive GWG for Chinese women.
It is imperative to offer pre-conception services that provide education and counselling on diet, physical activity and psychological factors for women, because pre-pregnancy BMI and gestational age may influence outcome of GWG. In addition, physical activity interventions for pregnancy are also difficult to maintain due to psychological changes during pregnancy. Therefore larger scale trials on psychological factors should be conducted to confirm the efficacy of interventions in preventing excessive GWG. Community-based physical activity and individualized dietary intervention during pregnancy appeared attractive to women and reduced the prevalence of excessive GWG[32]. NICE also recommends that local authorities and communities offer the opportunity for pregnant women to take part in physical activity[26]. In addition, psychological factors should be a cause for concern. Few studies took psychological factors into consideration for preventing excessive
Chapter 5 Conclusion
The findings of this systematic review may not be generalizable because of limited sample size and limited quality of RCTs. Nonetheless, diet and physical interventions do reduce weight gain for women during pregnancy, and have a positive effect on following GWG guidelines and health behaviour change. To prevent excessive GWG, one-to-one counselling on diet and physical activity is a popular measure in the majority of reviewed studies. The content of these interventions may be applied to Chinese women based on pre-pregnancy BMI. Since pregnancy is a special period, apart from keeping a healthy weight during pregnancy, the feasibility of physical activity interventions for pregnant women, and the evaluation of psychological changes is suggested for future intervention studies.
To clarify the effectiveness of diet and physical activity intervention on preventing excessive GWG, further meta-analyses of RCTs, especially in Chinese women, are needed.
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