Stillbirth at term in Iceland: Causes of death and patterns of placental injury

Abstract

Background

Iceland is a high-income country with <400.000 inhabitants and low stillbirth rate (SBR). Increased antenatal risk assessment and interventions in high-risk pregnancies doubled the induction rate after 2008.

Objective

Estimate the SBR at term, comparing an earlier (1996–2008) and latter (2009–2021) 13-year period, and describe causes of death and patterns of placental injury of infants stillborn at term.

Study design

Stillbirth at term was defined as antepartum or intrapartum death of an infant that was diagnosed after ≥37 weeks of gestation. All cases (n = 125) had placental examination. Histopathological slides were reviewed, and pattern of placental injury classified according to the Amsterdam consensus. Medical records were found for all mothers who had stillbirth at term and cause of death assigned according to the Stockholm classification of stillbirth.

Results

No decrease in the SBR at term was found between periods. Majority of deaths (72 %) were caused by cord complications and/or placental insufficiency and deaths attributed to placental insufficiency increased in the latter period. Placentas weighing under the 10th percentile were more common in the latter period, 43.5 % vs. 30.2 % (p < 0.05) as was chronic villitis of unknown etiology (VUE), 40.3 % vs. 12.7 % (p < 0.01).

Conclusion

Stillbirth at term has not decreased in Iceland, despite increased antenatal surveillance and induction rate, with more deaths attributed to placental insufficiency and VUE increasingly found in the later period. Further research is needed on the correlation of patterns of placental injury with clinical phenotypes of mothers and infants.