Exercise as it relates to Disease/The importance of exercise during pregnancy to decrease the likelihood of hypertension and gestational weight gain

This is a review of the original research "Exercise during pregnancy protects against hypertension and macrosomia: randomized clinical trial". (Barakat R, Pelaez M, Cordero Y, Perales M, Lopez C, Coteron J et al. 2016)

What is the background to this research?
Gestational hypertension is defined as blood pressure measuring 140/90 mmHg or higher. Hypertension is typically seen at >20 weeks gestation and it has been reported up to 10% of pregnancies experience some form of hypertension, increasing the risk for both mother and child during pregnancy and during birth. Hypertension is only becoming a more common feature in pregnancy. Obesity during pregnancy, Gestational Weight Gain (GWG), Gestational Diabetes Mellitus (GDM), pre-eclampsia and pregnancy induced hypertension can be linked to macrosomia (>4000g) and low birth weight (<2500g) in infants.

There have previously been a low number of studies investigating exercise programs in a large group of pregnant women with high adherence rates. Barakat et.al carried out this study to determine if exercise during pregnancy will protect against hypertension and macrosomia. These findings are shared globally to the medical and health industries to fill the gap. It is important to determine how effective exercise is during pregnancy to encourage expecting mothers to take care of themselves physically, and more importantly, to determine the risks when exercise is not undertaken whilst pregnant.

Where is the research from?
The research was conducted through the Technical University of Madrid, Spain over a period from December 2011 through to January 2015. All the authors, especially Ruben Barakat PhD, are apart of Physical Activity and Sports in Specific Populations (AFIPE) Research Group, and together have a strong reputation in the field of physical activity amongst pregnant populations. The study was reviewed by the ethics board at Hospital Severo Ochoa, Madrid Spain. It was published through the online Journal ‘Elsiver’ and through the American Obstetrics and Gynaecology journal - which is one of the most referenced journals by health professionals in the obstetrics and gynaecology industry. No obvious bias is apparent in the study or through organisational links, and there were no conflicts of interest mentioned.

What kind of research was this?
This study was a randomised controlled trial (RCT) where the subjects were randomly allocated into two groups; the control group and the exercise group. This method is useful in determining if the intervention is effective and differences amongst the two groups. Studies typically struggle with participation amongst subjects however the exercise group in this study had a high adherence rate.

Various studies examine the benefits of exercise whilst pregnant specifically looking at GDM or GWG but it is not common to assess them all together. Barakat et.al provides evidence of the successful effects exercise during pregnancy has on a variety of risks associated with pregnancy.

What did the research involve?
The study focused on a supervised exercise intervention during the early to late stages of pregnancy to determine if frequent exercise would lower the risk of chronic health diseases, which are proving to be quite common in pregnancy. A sample of 765 Spanish pregnant women were assessed for eligibility to participant in a RCT which was a well suited methodology for this intervention. The exercise intervention was made up of 10-12 participants per group, 3 days per week for 55 minutes. Music during exercise, a well air conditioned and well-lit room were features to maintain participant adherence. The main exercises for the intervention were:
 * aerobic exercise
 * aerobic dance
 * muscular strength
 * pelvic floor exercises
 * flexibility.

Heart rate monitors were required every session and each participant used a RPE scale.

Women in the control group were educated from their health care provider about the benefits of physical activity during pregnancy and were asked once per trimester what their exercise regime had been. All participants had their diastolic and systolic arterial blood pressure measures once each trimester to determine the risk of hypertension, defined as a diastolic blood pressure of >90mmHg and systolic blood pressure of >140mmHg.

What were the basic results?
Between the two groups, the exercise group significantly: Overall, participants in the exercise group gained less weight during their pregnancy compared to the control group (P = .01). Although the incidence of low birth weight did not change, the exercise group was found to have a lower incidence of macrosomia (P = .03) and the control group who did not exercise were 2.5 times more likely to give birth to a macrosomic infant (P = .04). Pregnant women in the control group were:
 * reduced hypertension in pregnancy (P = .009),
 * reduced preeclampsia in pregnancy (P = .03),
 * reduced GDM (P = .03).
 * 3 times more likely to develop hypertension during pregnancy
 * 1.5 times more likely to gain excessive weight.

Blood pressure results were not individually graphed, which would have been useful to see the decrease in hypertension in the exercise group overtime and the steady state or increase in hypertension for the control group. Specific exercise routines were not explicitly mentioned, which limits the option for other to replicate this intervention.

What conclusions can we take from this research?
Conclusions from this research can be applied to health professionals and pregnant women globally about the importance of exercise during pregnancy. This was a large study and could be applied and replicated by others to monitor exercise benefits in pregnant populations. Aerobic exercises and muscular strength exercises that begin in early gestation and frequently continued through to the end of the third trimester may be a strong preventative tool for decreasing the risk of developing hypertension, GWG, preeclampsia, GDM and macrosomia in infants.

In comparison to other studies, high adherence rates when exercising in a pregnant population is limited. From this study, enjoyable group exercising conditions seem to promote adherence and therefore should be taken into account when conducting future studies and applying to general population. Pre-exercise screening was not explicitly mentioned which is an extremely important step to take before starting an intervention, especially with high risk individuals who are pregnant. This is so appropriate care and monitoring is available in exercise interventions. Future studies could combine exercise regimes in pregnancy with food intake and determine what effects healthy eating combined with exercise could help with in pregnancy.

Practical advice
When prescribing an exercise regime in general but especially in pregnant populations, they must be tailored to the individual’s needs, including consideration frequency, intensity, duration and mode. It is important to check in regularly with your health professional or exercise coach in case exercises need to be modified or ceased for medical reasons. Exercise will not cure all co-morbidities of pregnancy but will help reduce them. Maintaining a healthy lifestyle inclusive of exercise and healthy eating pre, during and post pregnancy will increase the likelihood of a safer pregnancy.

Both the American College of Obstetrics and Gynaecology and Royal Australian and New Zealand College of Obstetrics and Gynaecology guidelines recommend at least 150-300 minutes of moderate intensity aerobic activity per week. Both guidelines suggest physical activity during pregnancy will assist with decreasing risk of hypertension, pre-eclampsia and GWG.

Further information/resources

 * The Royal Australian and New Zealand College of Obstetrics and Gynaecology
 * The American College of Obstetrics and Gynaecology
 * Adult Exercise Pre-Screening
 * Australian Government Department of Health
 * Physical Activity Australia
 * Healthy Eating During Pregnancy