Some studies have shown that high fevers during the first three months of pregnancy can affect the fetus's development while other studies have not confirmed these findings. However, women who are extremely fit actually have improved body temperature regulation and have decreased core body temperature during pregnancy. Because of the conflicting data available, general guidelines would include caution when exercising in very hot weather and attention to adequate fluid intake during exercise. This has a big impact on endurance and may result in a marked decrease in your exercise capability because of breathlessness, dizziness and fatigue. Women with anemia who want to continue their exercise program should eat an iron-rich diet, take extra vitamin C with meals to increase iron absorption and should take iron supplements if prescribed by their maternity care provider.
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.