Can a Fever Cause a Miscarriage?

Having a fever during pregnancy, particularly in the first trimester, can cause problems for a developing baby. However, researchers do not yet know whether having a fever during early pregnancy may actually cause a miscarriage. It is usually prolonged, high fevers that are thought to cause problems.

Miscarriage is common and between 15 and 20 percent of all pregnancies result in miscarriage. We have no idea what exactly causes the majority of miscarriages. Nevertheless, possible causes of miscarriage include the following:

• Abnormal uterine conditions like fibroids
• Fetal chromosome abnormalities
• Infections
• Poorly controlled diabetes
• Severe trauma

Some of the above conditions that predispose a person are preventable. For example, it's important to make sure that your diabetes is properly managed during pregnancy. However, some of the above conditions are outside of your control, such as fibroids or fetal chromosome abnormalities.

Risk of Neural Tube Defects

Some research does link hyperthermia, or abnormally high body temperature, to risk of neural tube defects and possibly miscarriage. One 2003 study looked at hot tub use and found weak evidence of an association between hot tubs and miscarriages. Furthermore, physicians routinely advise pregnant women to avoid soaking in hot baths for extended periods of time to be on the safe side.

Research looking specifically at maternal fevers has found that fevers seem to increase the risk of neural tube defects. (The most severe neural tube defects, such as anencephaly, can be fatal for the baby and thus cause pregnancy loss.) Fevers may also increase the risk of other developmental problems, such as heart defects.

Research findings have been less conclusive as to whether fever causes first-trimester miscarriage. A large 2002 study in The Lancet found no evidence of an association, although a 1985 case-control study by Johns Hopkins University researchers hinted at a link between fever and miscarriage.

Because of the possible risk of developmental problems, physicians often advise pregnant women to call when experiencing a fever over 101 degrees Fahrenheit. Remember to call your physician if you are ever concerned about an illness or other symptoms during pregnancy.