In his PhD theses, Kristoffer Myrstad Brodwall has studied risk factors for congenital heart defects based on information of all births in Norway between 1994 and 2009.


  1. Women who suffer from preeclampsia before 34 weeks of pregnancy have almost trefold increased risk of birthing a child with a severe heart defect.
  2. Siblings of children with a congenital heart defect have increased risk of being born with a heart defect themselves.
  3. Children with Down syndrome born with a heart defect have similar five-year survival to other children with Down syndrome.


Thesis: Congenital heart defects in Norway – A nationwide study of Down syndrome, maternal preeclampsia, and sibling recurrence risk, 1994-2009
Candidate: Kristoffer Myrstad Brodwall
Time: March 9, 2018 at 12:15
Place: Haukeland University Hospital, The Children and Youth Hospital: Auditorium
Link to university website (in Norwegian)


(1) Between 1994 and 2009, about 2500 children in Norway were born with a severe heart defect. The risk was 2.8 times higher if the mother had preeclampsia within gestational week 34, and was also increased in pregnancies complicated by severe preeclampsia after week 34. The association between preeclampsia and congenital heart defects was especially strong for atrioventricular septal defect.

Preeclampsia can not be the cause of congenital heart defect. Therefore, the researchers believe there might be a common etiology behind the two conditions. In total, more than 900,000 births were included in the analyses.

(2) Risk factors within the family seem to be important for the risk og congenital heart defects. 4.1 % of the children with older siblings with congenital heart defects were born with defects themselves. The risk was three to four times higher than in children with siblings without congenital heart defects. For severe heart defects, the risk was almost seven-fold higher, and the risk was even further increased in twins.

Data from almost 450,000 Norwegian pairs of siblings and 16,000 pairs of twins were analyzed in this study.

(3) Children with Down syndrome born with non-severe heart defects have the same chance of surviving the first five years as those born without heart defects. For the children with more severe congenital heart defects, however, the survival is substantially lower. More than half of all children born with Down syndrome in Norway between 1994 and 2009 had a heart defect.


(1) Brodwall, K., Leirgul, E., Greve, G., Vollset, S. E., Holmstrøm, H., Tell, G. S., & Øyen, N. (2015). Possible Common Aetiology behind Maternal Preeclampsia and Congenital Heart Defects in the Child: a Cardiovascular Diseases in Norway Project Study. Paediatric and perinatal epidemiology30(1), 76-85.

(2) Brodwall, K., Greve, G., Leirgul, E., Tell, G. S., Vollset, S. E., & Øyen, N. (2017). Recurrence of congenital heart defects among siblings—a nationwide study. American Journal of Medical Genetics Part A173(6), 1575-1585.

(3) Brodwall, K., Greve, G., Leirgul, E., Klungsøyr, K., Holmstrøm, H., Vollset, S. E., & Øyen, N. (2018). The five‐year survival of children with Down syndrome in Norway 1994‐2009 differed by associated congenital heart defects and extracardiac malformationsActa Paediatrica.

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