%0 Journal Article %T Physical Activity during Pregnancy: Impact of Applying Different Physical Activity Guidelines %A Katie M. Smith %A Christina G. Campbell %J Journal of Pregnancy %D 2013 %I Hindawi Publishing Corporation %R 10.1155/2013/165617 %X Multiple guidelines and definitions of physical activity (PA) have been used to study the benefits of activity during pregnancy. The different guidelines lead to a wide range of prevalence estimates and this has led to conflicting reports about activity patterns during pregnancy. A longitudinal study was conducted to assess PA using a pattern-recognition monitor for a 7-day period at week 18 ( ) and week 35 ( ) of pregnancy. The amount of activity performed and the number of women meeting six different PA guidelines were evaluated. Adherence to PA guidelines ranged from 5 to 100% and 9 to 100% at weeks 18 and 35, respectively. All women achieved the 500 MET-minute guideline and nearly all women accumulated ¡Ý150 minutes of weekly moderate-vigorous physical activity (MVPA) at both time points. Only 22% and 26% participated in ¡Ý3 sessions of MVPA lasting ¡Ý30 minutes at both time points and this further declined to 5% and 9% when the guideline was increased to ¡Ý5 sessions of 30 minutes. The amount of PA during pregnancy varied drastically depending on which guideline was used. Further research is warranted to clearly identify the patterns of activity that are associated with healthy pregnancy outcomes. 1. Introduction Views on physical activity and exercise during pregnancy have taken on new meanings and implications throughout history. The importance of maternal physical activity dates as far back as the third century BC when Aristotle eluded to the difficulty endured during childbirth as a result of a sedentary maternal lifestyle [1]. However, society and expert opinions have not always supported the prenatal exercise since that time. For many years maternal, exercise was thought to harm the fetus or promote adverse pregnancy outcomes such as preterm delivery and fetal growth restriction or small for gestational age infants [2, 3]. In 1985, the American College of Obstetricians and Gynecologists (ACOG) published the first exercise guidelines for pregnant women. These included limitations on heart rate and duration, restricting heart rate to 140 beats per minute, and exercise to no more than 15 minutes at a time [4]. Furthermore, women that were inactive prior to pregnancy were not advised to begin an exercise program while pregnant. Considerable evidence was published regarding the safety of maternal exercise between the 1980s and early 1990s supporting the need for updated and revised exercise guidelines [3, 5, 6]. Consequently, ACOG responded in 1994 by eliminating the constraints on heart rate and exercise duration, stating that exercise can be done in %U http://www.hindawi.com/journals/jp/2013/165617/