Exercise as it relates to Disease/Is physical activity during pregnancy influential on maternal weight and obstetric outcomes?

This page is a critique on research article The impact of physical activity during pregnancy on maternal weight and obstetric outcomes. Mizgier M, Mruczyk K, Jarząbek-Bielecka G, Jeszka J.Ginekologia polska.

What is the background to this research?
Regular physical activity in all phases of life, including pregnancy, promotes health benefits for the mother and reduces the risk of complications related to foetal development and chronic diseases in children later in life. However, the majority of the woman of childbearing age are overweight or obese. Inactivity in pregnancy and excessive weight gain have been recognised as an independent probability for maternal obesity and related pregnancy complications. Maternal weight pre and post-pregnancy affect mothers and children's health by significantly impacting the in utero environment on fetal development and the child's health throughout their lifespan. Underweight women tend to have low birth weight babies as opposed to obese women who have larger gestation (macrosomia) babies. A low-birth-weight infant is defined as less than 2,500g. Macrosomia, defined as birth weight greater than 4,000g, increases the risk of complications at delivery such as caesarean birth, vacuum extraction, episiotomy, acute haemorrhage, immediate adverse health effects, gestational diabetes, pregnancy-induced hypertension and an increased risk of obesity in childhood.

The US institute of medicine (IOM) published gestational weight gain recommendations for women based on pre-pregnancy body mass index (BMI) in the guidelines are as follows.

Women who exhibited recommended weight gain are at minor risk of complications throughout pregnancy and delivery. Mothers with excess weight gain relative to IOM recommendations more often have neonates that score below the APGAR'5 scale and are more inclined to experience complications. In previous studies, the risk of preterm birth, larger gestation babies (macrosomia), diabetes, preeclampsia, eclampsia and caesarean section increases with increased BMI.

Where is the research from?
This study was conducted by researches of the Institute of Dietetics, Department of Hygiene and Human Nutrition, Poznań University of Life Sciences; at the Gynaecology and Obstetrics Training Hospital, Poznań University of Medical Sciences. The study project was approved by the Independent Ethics Committee at the Karol Marcinkowski University of Medical Sciences, Poznań.

What kind of research was this?
This research was a quantitative assessment designed to assess the intervention of physical activity program of pregnant women throughout their second and third trimester, determining the effect on variables birth weight, appropriate maternal weight gain, the method of delivery and week of gestation. The data was measured through questionnaires and recorded with the ActiGraph GT3X monitor. The evidence provided can be considered a strong article as there isn’t much research comparing short and long term moderate physical activity in pregnant woman.

What did the research involve?
The method consisted of 57 pregnant women with uncomplicated single pregnancies participating in a 10 to 18-week physical activity program through their second and third trimesters. The woman were divided into two groups, short and long moderate physical activity, in comparison by their age, height, weight and body mass index pre and post-pregnancy. ActiGraph GT3X monitor monitored physical activity. Individual consultation with a dietitian was implemented every three weeks to obtain healthy nutrition throughout pregnancy. Data on delivery consisted of body weight, method of delivery, week of birth, gestation birth weight, baby length on study completion.

Exercise program

The physical activity program implemented was designed around the guidelines of the American Congress of obstetricians and gynaecologists. The program consisted of safe pregnancy activities of individualised pregnancy workouts, swimming, walking, cycling and yoga for 30 mins every day or most days of the week. In addition, applicants took part in a training session to assess their current health and fitness status and were advised on adjustments to their level of physical activity before commencement. Participant's physical activity was recorded with the ActiGraph GT3X monitor. In addition, the participants wore the devices on a flexible waistline belt due in daily activities.

Women were advised to not participate in physical activity if they experienced dizziness, headaches, chest pains, muscle weakness or oedema of the calves or any other abnormal signs.

The study's limitations were the small number of participants than anticipated inhibiting the association of physical activity and the pregnancy results of the investigation as well as participants lack of motivation to exercise can also limit findings. Furthermore, addressing the fetal physiological response to maternal physical activity such as heart rate changes would have been an interesting concept. Research has recognised that fetal heart rate increases by 10-30 beats per minute over the baseline of exercise exertion in minimum to moderate exercise.

What were the basic results?
Overall, the researchers concluded that there was a slight variance in weight gain. The women in the shorter duration of physical activity had six times greater excess weight gain than the normal range. The longer duration physical activity showed lower weight gain under the standard recommendation. The shorter duration physical activity group had twice as many cases of macrosomia and vacuum extraction occurring in the group. There were three cases of preterm births and three times as many low birth weight cases in the comparison group. No significance was found in terms of low birth weight or gestation at birth.

Unfortunately, due to the low participant rate, there wasn’t a possibility to show significance in the relationship between the duration of physical activity and macrosomia and obstetric outcomes. Therefore, further investigation is required.

What conclusions can we take from this research?
From the aspect of pregnant women, recent publications are increasing their focus on the impact of physical activity in pregnancy, whether beneficial or adverse to the pregnancy outcome. The research, to a degree, enhances the benefits of increased duration of moderate physical activity as it improves physical fitness and prevents excessive weight gain. However, it reported the shorter intensity and duration of physical activity decreased due to the increased weight changes in the third trimester, resulting in less than 21 minutes of physical activity. The recommendation for exercise is 30 minutes per day. Unfortunately, most pregnant women don’t adhere to regular exercise; therefore, they don’t meet the US institute of medicine standard for the minimum amount of exercise to stay healthy per day. The study also confirmed that physical activity positively affects obstetric outcomes as the number of vaginal births was comparable in both groups.

Further research on the influence of optimal type, frequency and intensity of physical activity programs and the affects on obstetric outcomes need further observation in larger population intervention.

Practical advice
Physical activity guidelines recommend at least 150 minutes of moderate-intensity activity spread out through the week. Women who regularly engaged in vigorous-intensity aerobic exercise or were physically active before conception can continue these activities under the guidance of a doctor, obstetrician - gynaecologist or obstetric care provider. Women with or without a sedentary lifestyle should be encouraged to participate in physical activity. When starting a new exercise program during pregnancy, the Australian guidelines suggest beginning at a light to a moderate exercise program with constant consultation with various professionals to adjust the program accordingly. Guidelines also stipulate if to cease exercise if a woman feels dizzy, abdominal pain, pain or oedema of the calf, vaginal bleeding/fluid, pelvic pain excessive fatigue.

Further information/resources

 * Pregnancy and exercise
 * Health channel pregnancy and physical activity
 * Active pregnancy
 * Pregnancy,birth,baby