New study links infection during labor to higher HIE risk
A major new study published in the American Journal of Obstetrics and Gynecology suggests that infection and inflammation during labor can make a baby’s brain more vulnerable to injury, while at the same time muting the very warning signs doctors rely on to detect a baby in distress. For families affected by hypoxic-ischemic encephalopathy (HIE), the findings help explain something many parents have struggled to understand: how a serious brain injury can happen even when the fetal heart rate monitor never showed the dramatic changes everyone expects.
What the study looked at
Researchers in Finland reviewed more than 317,000 full-term deliveries over a 20-year period. From that group, they identified 3,487 newborns with umbilical artery acidemia, a condition where the baby’s blood becomes too acidic due to a lack of oxygen during labor. They then compared babies who developed HIE with those who did not, looking closely at whether the mother had chorioamnionitis, an infection and inflammation of the membranes and fluid surrounding the baby.
Chorioamnionitis can be diagnosed two ways. Clinical chorioamnionitis is identified during labor through signs like maternal fever, rapid heart rate, and other markers of infection. Histological chorioamnionitis is confirmed after delivery, when a pathologist examines the placenta under a microscope. When the inflammation spreads to the umbilical cord itself, it is called funisitis, a sign that the baby’s own immune system has been activated.
What the researchers found
Among babies with acidemia, those exposed to chorioamnionitis were about four and a half times more likely to develop HIE than babies without the infection. Babies with funisitis faced even higher risk. The babies exposed to infection developed brain injury at milder levels of acidemia. In other words, a degree of oxygen deprivation that another baby might have tolerated caused lasting harm when inflammation was also present.
The study also found that infection changed how babies responded to the stress of labor on the fetal heart rate monitor. Babies exposed to chorioamnionitis showed fewer of the deep heart rate decelerations that typically alert the delivery team to a problem, and more frequent shallow decelerations that are easier to overlook. The researchers describe this as a two-hit model: inflammation lowers the threshold at which brain injury occurs, while also dampening the heart rate patterns that would normally signal a baby in trouble.
Why this matters for fetal monitoring
Fetal heart rate monitoring is one of the most important tools doctors and nurses have for protecting a baby during labor. The standard approach assumes that a baby in distress will show recognizable warning patterns. This study suggests that assumption may not hold when infection is present. The authors caution that the absence of deep decelerations should not be treated as reassuring when intrauterine inflammation is suspected, and that reliance on traditional pH thresholds may underestimate the risk of brain injury in these babies.
For delivery teams, the takeaway is that a laboring mother with signs of infection, such as a fever, may need heightened attention rather than routine monitoring. The full clinical picture matters, including evolving heart rate patterns, the presence of meconium-stained fluid, labor progress, and any evidence of infection.
What this means for families
Many parents of children with HIE are told that the monitoring strips looked fine, or that nothing could have predicted the injury. Research like this adds important context. When a mother showed signs of infection during labor and her baby later developed HIE, the way the medical team responded to those signs deserves a careful look. A failure to recognize infection, to account for it when interpreting the fetal heart rate tracing, or to act on a concerning overall picture may point to negligence. Every birth injury case is different, and only a thorough review of the medical records can determine what happened in an individual delivery.
Talk to our birth injury team
If your child was diagnosed with HIE and you had a fever or infection during labor, you deserve answers about what happened and whether it could have been prevented. The attorneys at Wais, Vogelstein, Forman, Koch & Norman, LLC have decades of experience investigating birth injury cases nationwide, including cases involving HIE and failures in fetal monitoring. Contact us today at 410-998-3600 for a free consultation.
