If you exercised regularly before pregnancy, there's no need to focus on your heart rate for exercise during pregnancy.

Years ago, some experts recommended a heart rate of no more than 140 beats a minute for exercise during pregnancy. Today, however, heart rate limits aren't typically imposed during pregnancy. For healthy women, the Department of Health and Human Services recommends at least 150 minutes a week of moderate-intensity aerobic activity — preferably spread throughout the week — without any specific heart rate limits. This recommendation also advises that pregnant women who were previously engaged in vigorous-intensity aerobic activity or who are highly active can continue their activities, provided they remain healthy and talk with their health care providers about any needed activity adjustments over time.

Still, reasonable precautions for exercise during pregnancy are important. Get your health care provider's OK for any exercise during pregnancy. This is especially important if you have known medical conditions or risks, including:

• A history of preterm labor
• An incompetent cervix (cervical insufficiency)
• Placenta previa — when your baby's placenta covers your cervix — during the third trimester
• Heart disease
• High blood pressure
• Poorly controlled type 1 diabetes

Pace yourself appropriately. In general, you should be able to carry on a conversation while you're exercising. If you can't speak normally while you're working out, you're probably pushing yourself too hard.

While exercising, stay well-hydrated, avoid exercises that require you to lie flat on your back for extended periods of time, and stop if you have unusual signs or symptoms, such as vaginal bleeding, chest pain or painful contractions. Contact your health care provider if you have any symptoms that concern you during your exercise.