Some women experience preterm contractions throughout their pregnancy. While preterm contractions do not always lead to preterm birth, they do increase a women's risk of preterm labor significantly. If you have frequent contractions during your pregnancy, strenuous exercise may lead to a higher rate of contractions. Weight-bearing exercise can increase pain levels and further stress the joints. Again, non-weight bearing exercise may help with these symptoms.
Swimming is particularly helpful.
Toxemia, or high blood pressure that develops during pregnancy, is thought to involve a severe problem with blood vessels throughout the body. Exercise can worsen toxemia and should not be continued. Placenta Previa is a condition where the placenta grows low in the uterus and actually covers the opening to the cervix. It can cause severe bleeding during pregnancy. Any women with placenta previa or with vaginal bleeding of an unknown cause should not participate in an exercise program.