Exercise as it relates to Disease/Effect of physical activity and weight gain in obese pregnant women

This Wikibooks page is a critique of the research article "Exercise Training and Weight Gain in Obese Pregnant Women: A Randomised Controlled Trial (ETIP Trial)" by Garnæs, Mørkved, Salvesen and Moholdt (Jul. 2016).

This page was created as an assignment for the unit Health, Disease and Exercise at the University of Canberra (Sep. 2020).

What is the background to this research?
Gaining weight during pregnancy is normal, yet the amount of weight gained is important for the long-term health of both the mother and the baby. Recent studies suggest that approximately one-third (32%) gained the recommended amount of weight during pregnancy; whereas, the majority of women were outside the recommended guidelines (48% too much and 21% too little). The ideal amount of weight is based on the mother's body mass index (BMI) before falling pregnant. For example, overweight/obese women should gain less throughout pregnancy than someone who is underweight/normal. Consequently, women that are already an unhealthy weight and further gain too much while being pregnant, increase the risk of numerous health complications such as; preeclampsia, gestational diabetes mellitus (GDM) and caesarean birth.

The present study being critiqued, aims to determine if regular physical activity in overweight/obese pregnant women could reduce gestational weight gain (GWG) and hence prevent other negative health complications. The study also compared the effects of exercise across 30 different measures including but not limited to; blood pressure, blood measurements, skinfold thickness and body composition. Since maternal obesity is related to GWG and GDM, there is a significant demand to evaluate whether prescribing exercise training programs to overweight/obese pregnant women could considerably decrease the risk of detrimental health complications for future pregnancies.

Where is the research from?
The authors of this study are Kirsti Krohn Garnæs (researcher), Siv Mørkved (professor), Øyvind Salvesen (associate professor) and Trine Moholdt (researcher) from the University of Science and Technology in Norway (NTNU). The content of the study is likely to be of high-quality as all participating scientists have extensive knowledge on the effects of exercise on the human body as well as specialising in female research, particularly on the reproductive system. The Norwegian Fund for Post-Graduate Training in Physiotherapy as well as The Liaison Committee between the Central Norway Regional Health Authority partnered with the NTNU were the main organisations for funding and supporting this study. With this being said, it was specifically noted that there was no conflict of interest/bias as the sponsors had zero input in the way the study was designed, how the data was collected and analysed, the decision to publish the article nor the preparation of the manuscript.

What kind of research was this?
This study was conducted as a randomised controlled trial (RCT), meaning participants were randomly assigned to one of two possible groups. One being the experimental group receiving the intervention being tested and the other the control group receiving conventional treatment. The expected difference between the experimental and control group for this research design is the outcome variable being studied, in this case the effect of physical activity.

What did the research involve?
Methods used for this research were taken from the previous study protocol Exercise Training in Pregnancy for Obese Women (ETIP): Study Protocol for a Randomised Controlled Trial; however, the following changes were made to predominately increase recruitment into the trial; body composition measurement, extension for baseline testing and inclusion as well as lowering BMI criteria.

This was a single centre study consisting of 91 pregnant women with a BMI of ≥ 28 kg/m2. Participants were then randomly assigned to either the exercise group or control group.

Exercise group

 * Weekly 3 x 60 minute supervised hospital sessions (35 minutes of moderate intensity cardio followed by 25 minutes of strength training)
 * Weekly 1 x 50 minute at home program (35 minutes of endurance training followed by 15 minutes of strength training)
 * Standard maternity care

Control group

 * Standard maternity care

All physiological assessments were conducted at pregnancy 12–18 weeks, then again at 34–37 weeks and lastly on delivery day.

The main limitation of this trial was the reduced statistical power. The study aimed to recruit a total of 150 participants as opposed to the 91 they received which could have been a result of the recruitment criteria, time frame as well as the population demographic. In addition, it was noted that only 50% of the participants in the exercise group performed the exercise training program making it extremely difficult to interpret data and detect any possible effects in the intervention. This should be considered when analysing the results.

What were the basic results?
Overall, the research concluded that women in the intervention group gained 10.5 kg on average (towards the end of pregnancy); whereas, the control group only gained 9.2 kg on average. Upon examining the populations average BMI, the amount of weight gained throughout pregnancy could be considered 'healthy' when comparing with other normative data. It was also evident towards the end of the last trimester, fewer women in the exercise group had GDM and their diastolic/systolic blood pressure was lower compared to those in the control group. All other measures tested showed no apparent differences between the two groups.

Unfortunately, the study found no changes in GWG between women assigned to an exercise program to those just receiving standard maternity care. Therefore, the effectiveness of prescribing exercise training programs to overweight/obese pregnant women to prevent GWG and GDM is still unclear and further studies are required.

What conclusions can we take from this research?
According to this study, implementing exercise to specifically reduce GWG and GDM in overweight/obese pregnant women has little to no effect. This implies that both endurance and strength training followed by standard maternity care is just as effective as maternity care alone. The methodology and recruitment process for the study question the validity of the findings as the trail consisted of fewer participants than initially expected with only 50% complying to the described protocol. With these inconsistencies, it is unclear whether exercise alone would produce similar results if participants correctly adhered to the intervention program proposed. Likewise, exercise weight loss programs have been proven to be effective, especially when adopting a balanced diet.

In future, studies should aim to incorporate different forms of exercise followed by appropriate nutrition to help encourage overall health and weight loss in overweight/obese pregnant women. Other factors including demographics, predisposition for health conditions, previous pregnancies and how these factors could influence the effect of GWG or the likelihood of developing GDM in already unhealthy women. Not only physical measures should be considered, but physiological parameters such as the link between depression and weight gain should further be explored.

Practical advise
Exercise programs are an effective way for losing weight; however, results are subjective and rely on self-motivation. Unfortunately, it seems that overweight/obese pregnant women lack the ability and desire to change their lifestyle as illustrated by the compliance rate of this study. Before becoming pregnant, it is recommended that women consult their general practitioner (GP) for a pre-pregnancy check-up. From there, any potential risks for the mother and baby are discussed as well as any medical concerns that need to be addressed such as weight loss. Even though weight is a sensitive topic for some, it is advised that women fall within a healthy BMI before conceiving. Not only does this protect the mother's health and prevent complications during birth, but also the baby's well-being.

Further information/resources

 * The Women's weight gain guideline
 * Complications associated with obesity in pregnancy
 * Healthline strategies to safely lose weight while expecting
 * Pregnancy approved exercises