Can a Fever Cause a Miscarriage?

Pregnant woman having her temperature taken

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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.

5 Sources
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  1. Sass L, Urhoj SK, Kjærgaard J, Dreier JW, Strandberg-larsen K, Nybo andersen AM. Fever in pregnancy and the risk of congenital malformations: a cohort study. BMC Pregnancy Childbirth. 2017;17(1):413. doi:10.1186/s12884-017-1585-0

  2. Cohain JS, Buxbaum RE, Mankuta D. Spontaneous first trimester miscarriage rates per woman among parous women with 1 or more pregnancies of 24 weeks or more. BMC Pregnancy Childbirth. 2017;17(1):437. doi:10.1186/s12884-017-1620-1

  3. Li DK, Janevic T, Odouli R, Liu L. Hot tub use during pregnancy and the risk of miscarriage. Am J Epidemiol. 2003;158(10):931-7. doi:10.1093/aje/kwg243

  4. Layde PM, Edmonds LD, Erickson JD. Maternal fever and neural tube defects. Teratology. 1980;21(1):105-8. doi:10.1002/tera.1420210114

  5. Andersen AM, Vastrup P, Wohlfahrt J, Andersen PK, Olsen J, Melbye M. Fever in pregnancy and risk of fetal death: a cohort study. Lancet. 2002;360(9345):1552-6. doi:10.1016/S0140-6736(02)11518-2

Additional Reading
  • Anderson, Anne-Marie Nybo, Pernille Vastrup, Jan Wohlfahrt, Per Kragh Anderson, Jorn Olsen, and Mads Melbye. "Fever in pregnancy and risk of fetal death: a cohort study. The Lancet 2002.
  • Botto, L.D., M.C. Lynberg, and J.D. Erickson. "Congenital heart defects, maternal febrile illness, and multivitamin use: A population-based study." Epidemiology Sept 2001.
  • Chambers, Christina, Kathleen A. Johnson, Lyn M. Dick, Robert J. Felix, and Kenneth Lyons Jones. "Maternal fever and birth outcome: A prospective study." Teratology 1999.
  • Kline, Jennie, Zena Stein, Mervyn Susser, and Dorothy Warburton. "Fever During Pregnancy and Spontaneous Abortion." American Journal of Epidemiology 1985.
  • Li, De-Kun, Teresa Janevic, Roxana Odouli, and Liyan Liu. "Hot Tub Use during Pregnancy and the Risk of Miscarriage." American Journal of Epidemiology 2003.

By Krissi Danielsson
Krissi Danielsson, MD is a doctor of family medicine and an advocate for those who have experienced miscarriage.