Norwegian research explores preeclampsia as a potential cause of cerebral palsy
Findings in a recent population-based study investigating links between preeclampsia in pregnancy and spastic cerebral palsy were both suprising and clinically sensible to Canadian CP researchers.
Authors of the Norwegian study sought to determine whether preeclampsia had a direct effect resulting in unilateral (one-sided) CP, noting that pre-term birth and low birth weight are known risk factors for CP, as well as potential outcomes of preeclampsia, a condition in pregnancy in which blood pressure is elevated and excess protein is found in maternal urine (proteinuria).
Four percent of pregnancies are affected by preeclampsia, and a few publications have shown clear links between the condition, premature births, and CP, according to NeuroDevNet CP research group lead Dr. Darcy Fehlings. "This study also shows a link with term delivery, and then further clarifies it by noting that there is a link with preeclampsia, being small for gestational age (SGA) and CP."
By linking clinical data for 849 children from the Norwegian Cerebral Palsy Registry with perinatal data for 600,000 children collected at delivery by the Medical Birth Registry of Norway, the investigators found that being born small for gestational age (SGA) increased risk of CP 3-fold in preeclampsia exposed infants, while prematurity (<32 weeks) in exposed infants increased CP risk 20-fold. Among children born at term, preeclampsia was a risk factor for cerebral palsy only when the children were small for gestational age.
"This makes clinical sense,” said Dr. Fehlings.“The other strong aspect of this paper is that it comes from the Norwegian population-based registry, so the quality of data is good and can be generalized.”
Noting that he was surprised by the lack of association with a CP subtype in the Norwegian study, NeuroDevNet researcher Dr. Steven Miller concurred that the work speaks to the value of a CP registry. Dr. Miller is conducting a Network-funded neuroimaging study evaluating the impacts of pre-natal administration of magnesium sulfate in preventing infant stroke.
“We recently found that postnatal growth in pre-term infants is important for cortical development,” added Dr. Miller, “so the SGA findings in term babies are very congruent – showing the importance of growth in the third trimester to brain health.” (Vinall et al. Sci Transl Med. 2013 Jan 16;5(168):168ra8)
Drs. Fehlings, Miller and other NeuroDevNet CP researchers are playing key roles in championing ongoing development of a cross-Canada CP registry, and are investigating additional inventions to prevent pre- and perinatal stroke such as infant cooling, and consumption of broccoli sprouts during pregnancy. Information about the Canadian registry for the public and access researchers will be added to the NeuroDevNet website in the Fall.
Mediators of the association between pre-eclampsia and cerebral palsy: population based cohort study BMJ 2013; 347 f4089 (Published 9 July 2013) is freely available online.