A review of stillbirth definitions: A rationale for change

Stillbirth definitions vary between countries around the globe. The purpose of this paper was to explore stillbirth definitions used by high income countries around the world, specifically compared to Ireland, their stillbirth and mortality rates and to examine how these rates are influenced by standards of care, especially resuscitation efforts within the delivery room for very preterm infants. A literature review was performed using PubMed, Academic Search Complete, MEDLINE, and CINAHL. These databases were searched with the terms "(stillbirth OR still birth OR stillborn) AND (definition OR registration OR registry)" and "(fetal OR neonatal OR neonate) AND Viability AND Gestational Age" in two separate searches. The database searches returned 1081 results involving stillbirths and 164 results for neonatal viability. After title, abstract, full text review, and reference review 33 papers remained for use in this study. Within the European Union (EU), 59.2 % (n = 16), 14.8 % (n = 4), 11.1 % (n = 3), and 3.7 % (n = 1) countries classify stillbirths at gestational ages of ≥22 weeks, ≥24 weeks, ≥28 weeks, and ≥180 gestational days respectively. The median stillbirth rate in Europe using ≥28 weeks gestational age as a cut-off was 2.7 per 1000 births, but this increased to 3.3 per 1000 births when stillbirths from 24 to 27 weeks gestation were included. Of the thirteen countries whose mortality data was examined, survival rates for liveborn infants ranged from 0-37.3 %, 1.1-64.5 %, 31.0-77.7 %, and 59.1-85.7 % for the gestational ages of 22, 23, 24, and 25 weeks, respectively. In 1995, survival rates for the United Kingdom and Ireland were only 26 % for those born at 24 weeks gestation, however this has almost doubled in Ireland to 56.6 % in 2014-2017. Survival rates have improved to the point that, in 2014-2017, the survival rate of infants born at 23 weeks gestation (32.3 %) was 6 % higher than the rate for those born at 24 weeks gestation in 1995. Due to the improvement in survival rates, multiple international organisations recommend recording stillbirths from 22 weeks gestation and/or 500 g. Based on the findings from this review, and due to improving survival rates for periviable infants, it is recommended the stillbirth definition in Ireland should be updated to ≥22 weeks' gestation and ≥400 g to comply with improved medical developments.