Maternal Fever During Pregnancy Associated with Higher Risk of Adverse Birth Outcomes, According to New Review led by AHN Maternal Fetal Medicine Physician

• Review highlights association between maternal hyperthermia and structural birth defects, neurodevelopment disorders, fetal growth restriction and even pregnancy loss
• AHN experts advocate for regular folic acid intake as well as acetaminophen use for fever management to best safeguard mothers, newborns

PITTSBURGH, July 20, 2026 /PRNewswire/ -- During pregnancy, fever is common, with roughly 1 out of 5 patients reporting the occurrence sometime during their gestational period.

Though they are common, fevers aren't always benign for developing babies. A new report published by Allegheny Health Network (AHN) maternal fetal medicine physician Peeraya Sawangkum, MD in Birth Defects Research Journal (doi.org/10.1002/bdr2.70041) highlights that hyperthermia (fever) – especially in the first trimester — may be linked to a higher risk of birth defects and other complications for newborns.

Dr. Sawangkum's literature review analyzed data published worldwide over the last several decades. Findings showed that maternal fever is associated with an increased risk of miscarriage, neural tube defects, craniofacial anomalies, congenital heart defects, fetal growth restriction and neurodevelopmental disorders in children.

The review also highlighted links between maternal fever and pregnancy loss, fetal growth restriction, and other complications.

More specifically, maternal reporting of a fever in conjunction with the common cold, influenza, tonsillitis, gastroenteritis and recurrent facial herpes infections during pregnancy was linked to a higher risk of congenital conditions such as spina bifida, fetal cleft lip and palate, cardiac defects and colon atresia (portion of the large intestine is absent at birth).

"The exact mechanism by which maternal fever causes birth defects is still poorly understood, but we do understand that duration, fever severity, and time of occurrence during gestation all play a critical role," said Dr. Sawangkum. "However, studies have shown that preconception and prenatal supplementation with folic acid and treatment of fever with antipyretics may reduce fever-related pregnancy risks."

While researchers are still working to better understand exactly how fever affects a developing baby, evidence suggests that high temperatures and inflammation can interfere with important proteins essential to fetal development. The study found that both the timing and length of a fever matter, with the first trimester appearing to be the most critical period of risk.

Maternal fetal medicine experts concluded that using antipyretic (fever-reducing) medicines and taking folic acid supplements before and during pregnancy can help reduce the risk of birth defects. In fact, some studies have shown that patients who reported high fevers but did not use medicine to lower their temperature were more likely to have babies with birth defects.

Acetaminophen is recommended as the first-line treatment for fever during pregnancy, but its use has decreased in the wake of unfounded claims tying its use in pregnant populations to childhood autism. A study published in The Lancet showed that national rates of acetaminophen orders for pregnant emergency department patients in the US have decreased by 10% over the past year.

"Maternal fever is a modifiable risk factor for adverse pregnancy outcomes, and scientific evidence demonstrates that the benefits of acetaminophen to manage fever far outweigh the risks," said Dr. Sawangkum. "It is a safe, proven intervention for maternal hyperthermia and we strongly encourage pregnant patients to treat fevers promptly, especially during early pregnancy, and to discuss any illness or fever with their clinical team."

Allegheny Perinatal Associates, AHN's maternal-fetal medicine practice, provides comprehensive care for patients experiencing high-risk pregnancies across western Pennsylvania. The multidisciplinary team includes board-certified maternal-fetal medicine physicians, advanced practice providers, genetic counselors, specialized sonographers, and nursing staff who collaborate closely with obstetricians to care for all high-risk patients.

Through advanced prenatal diagnostics, fetal monitoring, genetic counseling and evidence-based treatment, the practice is dedicated to improving maternal and neonatal outcomes while advancing research that helps make pregnancy safer for families throughout the region.

"By ensuring patients have access to evidence-based guidance, prompt fever treatment and appropriate prenatal care, we have an opportunity to reduce preventable complications and help more families achieve healthy pregnancy outcomes," said Dr. Sawangkum.

About Allegheny Health Network:
Allegheny Health Network (AHN.org) is an integrated health care delivery system serving the greater Western Pennsylvania region. The network is composed of 16 hospitals, ambulatory surgery centers, Health + Wellness Pavilions, an employed physician organization, home- and community-based health services, a research institute, and a group purchasing organization. AHN provides patients with access to a complete spectrum of advanced medical services, including nationally recognized programs for primary and emergency care, cardiovascular disease, cancer care, orthopedic surgery, neurology and neurosurgery, women's health, diabetes and more. AHN employs approximately 27,000 people, has 3,000 physicians on its medical staff, and serves as a clinical campus for Drexel University College of Medicine, Lake Erie College of Osteopathic Medicine and Duquesne University Nasuti College of Osteopathic Medicine.

SOURCE Allegheny Health Network