During the first trimester of pregnancy, you generally have free reign to be as active as you'd like. According to the "The Everything Pregnancy Fitness Book," women who are in the early stages of pregnancy may continue their usual fitness regimen, with a few tweaks thrown in for safety reasons. However, any exercise restrictions that you have during your first trimester should be followed throughout the remainder of the pregnancy.
High Risk Activities
The American Pregnancy Association says that, starting in the first trimester, pregnant women should avoid high-risk fitness activities. Particularly dangerous forms of exercise such as skiing, water skiing, mountain climbing and horseback riding carry with them a serious risk of falling, which can induce miscarriage. They also require quite a bit of balance to participate in without getting injured. As your body is changing and adjusting throughout your pregnancy, your center of gravity will probably be slightly off, which increases the risk of something going wrong.
Avoid contact sports such as soccer, football and basketball during your first trimester of pregnancy. They carry a serious risk of abdominal trauma, which can cause fetal distress and even miscarriage. Additionally, "The Everything Pregnancy Fitness Book" says that many doctors advise pregnant women to avoid racquet sports such as tennis from the start. Often, these activities involve abrupt side-to-side movements and present the added risk of blunt abdominal trauma as the ball bounces quickly around the court. Replace high impact activities with low impact exercise programs, such as yoga.
"The Everything Pregnancy Fitness Book" advises women, particularly those in their first trimester, to avoid outdoor workouts during the summer, as well as other situations in which they could become overheated. Overheating and dehydration are bigger concerns in the first trimester because the fetus is more susceptible to your body's temperature changes. When your body becomes too hot, it diverts blood flow from the uterus to cool your system. Because so many of the baby's vital organs form during the first trimester, some doctors feel that overheating creates a small but serious risk of birth defects.