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Kids born to mothers accidentally injured during pregnancy had a heightened risk of developing cerebral palsy, according to a retrospective study.

Crude estimates showed a mean cerebral palsy incidence of 4.36 per 10,000 child-years for those exposed to unintentional maternal injuries in utero versus 2.93 per 10,000 child-years among those who were unexposed, representing a modest 33% higher risk in adjusted analyses (adjusted HR 1.33, 95% CI 1.18-1.50), reported Asma Ahmed, MD, PhD, MPH, of the Hospital for Sick Children Research Institute in Toronto, and colleagues.

More serious maternal injuries carried a higher risk of cerebral palsy, as injuries resulting in hospitalization within a week of the incident were associated with more than double the risk of the condition (adjusted HR 2.18, 95% CI 1.29-3.68), the researchers wrote in .

Severe injuries that resulted in delivery had the greatest odds of cerebral palsy in offspring (adjusted HR 3.40, 95% CI 1.93-6.00), Ahmed's group found.

"This research, the first and largest population-based cohort study, to our knowledge, suggests a role of maternal injury during pregnancy in fetal neurodevelopment," Ahmed and colleagues wrote, noting that the study showed positive associations between accidental maternal injury and cerebral palsy overall and across several classifications including injury frequency, severity, and mechanism.

The study authors added that "these results suggest that monitoring of children exposed to maternal injury in utero may contribute to early detection of adverse neurodevelopmental outcomes and thus to the provision of optimal management and needed support."

In an , Zeyan Liew, PhD, MPH, and Haoran Zhuo, MPH, both of the Yale School of Public Health in New Haven, Connecticut, said that this study "highlights the need for better characterization and monitoring of potential long-term health consequences of fetal exposure to maternal injuries." However, they added that mothers affected by these injuries should be reassured that the absolute risk of offspring developing cerebral palsy -- especially for mild injuries -- is low.

Liew and Zhuo also stated that while this study attempted to control for several factors, there are remaining concerns of residual confounding. They noted that further investigation into whether these injuries disproportionately affect vulnerable communities as well as future studies that differentiate how perinatal risk factors, including maternal injuries, lead to certain cerebral palsy subtypes are needed.

Injuries affect between 6% to 8% of pregnant people, with most of those injuries being unintentional. Vehicle crashes and falls are the most common unintentional injuries in pregnancy, Ahmed's group wrote.

In this study, Ahmed's group linked national datasets to evaluate the association between unintentional maternal injuries that occur in pregnancy and the risk of cerebral palsy in offspring. They conducted a retrospective, longitudinal cohort study of pregnant patients in Ontario between April 2002 and March 2017. All infants were born after 20 weeks' gestation and followed until March 2018. The researchers excluded stillbirths from the analysis.

Ahmed's group identified maternal injuries using hospital discharge records, grouping the injuries by severity. Non-severe injuries included those treated in the emergency department that did not require a hospital admission, while severe injuries encompassed those treated as inpatients. Intentional injuries, such as suicide attempts or domestic violence, were excluded from the analysis.

The researchers analyzed the frequency of injuries, the timing of injuries relative to delivery, and the trimester in which the injury occurred. They identified diagnoses of cerebral palsy in kids between birth and up to 16 years using billing claims data.

Ahmed and colleagues adjusted for covariates including maternal age, parity, the start of prenatal care, rural residence, and socioeconomic characteristics.

Of more than 2 million children included in the study, 81,000 were exposed to an unintentional maternal injury in utero. The mean gestational age at delivery was 39 weeks' gestation. Young mothers, those with a substance use disorder, those who received provincial drug benefits, and those living in rural areas were more likely to experience an unintentional maternal injury in pregnancy.

The most common injuries were falls, transport-related injuries, or those related to mechanical forces, such as being struck by an object or by another person. Overall, 8.1% of exposed women had more than one unintentional injury during their pregnancy. Additionally, 2.7% of women were hospitalized after the injury, and 1.6% delivered their baby within a week of injury.

Over the 8 years of median follow-up, 5,317 children were diagnosed with cerebral palsy (incidence rate of 2.99 per 10,000 child-years). Among them, 5.5% were exposed to an unintentional maternal injury in utero.

Injuries that occurred earlier in pregnancy posed a greater cerebral palsy risk for children than those that occurred in the third trimester, but "the coefficients across timing of injury categories were not statistically heterogeneous," the authors noted.

Ahmed and colleagues acknowledged that misclassification of maternal injuries and cerebral palsy was possible, noting that administrative databases lack a clear definition for cerebral palsy and only capture cases that present for medical care. They added the databases used in this study lacked data on individual maternal socioeconomic characteristics, including education, occupation, and lifestyle factors.

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