Incorporating Current, Evidence-Based Prenatal Fitness Guidelines in Your Practice

fitness during pregnancy

One of the first questions I frequently get from newly pregnant clients is whether it’s safe for them to start or continue an exercise routine during pregnancy. They may have received outdated advice from friends, family, and even medical professionals who aren’t up to date on current guidelines. This barrage of conflicting information can be confusing for pregnant women and may discourage them from exercising.

It’s vital for health and fitness professionals to be able to offer up-to-date, evidence-based prenatal fitness guidelines when working with this population, both to ensure their exercise routine is safe and effective, as well as to provide support and encouragement so their clients can optimize their health during pregnancy.

The American College of Obstetricians and Gynecologists (ACOG) supports the health benefits of prenatal fitness, which include reduced excess weight and fat gain, lower rates of birth complications, and improved fetal response to stressors, and they continue to update their guidelines for prescribing prenatal exercise.1, 2

Prenatal Exercise Prescription

There are four components that comprise an exercise prescription:

  • Intensity
  • Duration
  • Frequency
  • Type

You may have worked with these components when developing exercise routines for non-pregnant clients, but for pregnancy the recommendations are more specific, as are the modifications.

Exercise Intensity

When prescribing an exercise intensity range for a pregnant client, the target range should remain in the moderate to somewhat hard level. However, instead of using training heart rate to monitor exercise intensity during pregnancy, the use of a perceived exertion scale is a more accurate assessment for determining how challenging the exercise level is on her body.

Another easy way to measure exercise intensity is the “talk test.” The rule of thumb is that the exercise intensity should be at a level that feels challenging but not so difficult that the client is too out of breath to talk.

The reason training heart rate isn’t used to monitor prenatal exercise intensity is that the cardiorespiratory changes of pregnancy affect heart rate response to exertion, making the use of heart rate less accurate at measuring true exertion level. In addition, the physiological changes of pregnancy and increased weight impact the level of exertion.

In essence, pregnancy is akin to wearing a backpack that is filled with more weight each week. This analogy can assure pregnant women who are distressed that they’re unable to continue their earlier pregnancy workloads because of fatigue that they’re not getting less fit but are actually working harder. The “backpack” is a lot heavier at 35 weeks than it was at 20 weeks, so her workload is higher—even at the same level of activity.

Exercise Duration

Exercise duration for pregnant clients should tend towards longer periods of exercise instead of high-intensity bursts. The goal is to maintain at least 20 to 60 or more minutes of exercise.

The longer duration allows for more fat-burning aerobic activity and is usually better tolerated. If a duration of 20 minutes can’t be maintained, the intensity level should be reduced until the lower end of duration can be reached.

Exercise Frequency

Ideally, pregnant women should aim for three to six days of cardiovascular exercise, as the more frequently she exercises, the more benefits she will gain. Also, the more fitness becomes a habit, the more compliant she will be with her routine.

Exercise Type

The type of exercise that’s ideal for pregnancy depends on each client. It’s helpful to include several types of activities so she uses all muscle groups and avoids overuse from doing just one type of exercise.

A mix of weight-bearing and non-weight-bearing exercise works well for most women, and the following is a list of activities that can be easily modified throughout pregnancy:

  • Walking
  • Running
  • Biking
  • Hiking
  • Swimming
  • Exercise machines such as elliptical trainers, rowers, and stationary bikes

There are absolute contraindicated activities (see below), but outside of those sports, most activities can be modified to be safe for pregnancy.

The following activities are absolutely contraindicated during pregnancy:

  • Water-skiing
  • Scuba diving
  • Very high-altitude sports


As pregnancy progresses, it becomes more challenging to maintain the same exercise routine without modifications. When a woman finds that she is unable to maintain her exercise duration and frequency when exercising at her usual intensity level, modify the routine by dropping down the intensity a bit. I always prefer reducing intensity before cutting duration or frequency, and remember—every week of pregnancy adds to the load that the pregnant client is carrying.

The type of exercise may also need to be modified over time, especially if the pregnant client develops discomfort with certain activities. Round ligament pain can make weight-bearing exercise painful, so switching to a non-weight-bearing exercise, such as stationary biking, will help her continue to exercise comfortably. Toward the end of pregnancy, edema and musculoskeletal discomfort can be eased by exercising in a pool. For some women, that may be the only activity they feel comfortable doing at that point.

Supporting the pregnant client by providing encouragement through education on the benefits of prenatal fitness, along with aiding her in developing an evidence-based fitness program, will improve both her health and the wellbeing of her fetus. Remember that each woman’s needs and goals will be different and will change as her pregnancy progresses, so health and fitness providers with the knowledge and skills to prescribe and modify a prenatal fitness routine play a vital role in improving pregnancy outcomes.

  1. American College of Obstetricians and Gynecologists. (2015). Physical activity and exercise during pregnancy and the postpartum period. Committee Opinion No. 650. Obstetrics and Gynecology, 126:e135–142.
  2. Wiebe, H. W., Boule, N. G., Chari, R., & Davenport, M. H. (2015). The effect of supervised prenatal exercise on fetal growth: a meta-analysis." Obstetrics and Gynecology, 125(5):1185–1194.