Neuro-developmental outcomes in preterm infants exposed to chorioamnionitis or preeclampsia

Despite the advances in perinatal care over the last decade, the prevalence of major neonatal and long-term morbidities has not significantly changed and still a high proportion of very preterm infants survive with long-term neurodevelopmental impairments. In fact, several postnatal factors such as intraventricular haemorrhage, ventilation and bronchopulmonary dysplasia, inflammatory conditions such as sepsis and necrotizing enterocolitis, and poor postnatal growth have been linked to impaired neurodevelopmental outcome.
The developing premature brain is highly vulnerable to intrauterine and perinatal events. In particular, maternal preeclampsia and chorioamnionitis may often lead to premature birth. Both conditions may harm the foetal brain: maternal preeclampsia interferes with placental blood supply and leads to chronic intrauterine hypoxia, that may cause ischemic damage and reduce foetal brain growth. On the other hand, chorioamnionitis exposes the immature brain to high levels of circulating cytokines that have been associated with neuronal apoptosis and lead to periventricular leucomalacia. However, information on the neurodevelopmental outcome in very preterm infants exposed to preeclampsia and chorioamnionitis is limited, and no study has compared these two groups so far.
On this basis, a Swiss group has conducted a case-control study on infants with maternal preeclampsia, chorioamnionitis, and controls (n=33 in each group; median gestational age: 29 weeks, range 25–32) to investigate whether neurodevelopmental outcome assessed at 2 years of age differs between very preterm infants exposed to preeclampsia, chorioamnionitis, and controls.
The median mental developmental index (MDI) was 96 in the control, 90 in the chorioamnionitis and 86 in the preeclampsia group. Preeclampsia infants had a lower MDI compared with the control group (univariate p=0.021, multivariate p=0.183) and with the chorioamnionitis group (univariate p=0.242; multivariate p=0.027). Median psychomotor index was 80.5 in the control, 80 in the preeclampsia and 85 in the chorioamnionitis group, without any significant inter-group difference. Chorioamnionitis or preeclampsia exposure was not associated with major neurodevelopmental impairments (cerebral palsy, MDI<70, PDI<70).
In conclusion, these preliminary results suggest that chorioamnionitis and preeclampsia have a relatively minor impact on long-term neurodevelopmental outcome in very preterm infants. Although placental insufficiency caused by maternal preeclampsia may reduce performance at 2 years of age, this was not associated with an increase of severe disabilities, even if the study may be underpowered to detect such differences. By contrast, well-described postnatal risk factors such as mechanical ventilation, BPD, postnatal growth failure and sepsis affected long-term development more than these conditions. It must be emphasized that larger prospective trials are urgently needed to improve our understanding of long-term outcome in infants exposed to chorioamnionitis or preeclampsia.

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