Maternal and fetal baseline characteristics
Baseline maternal and fetal characteristics of stillbirths (n=144) and controls (n=247) are shown in Table 1 . Our IUFD cohort consisted of 73 (50.7%) male and 71 (49.3%) female fetuses between 21+1 and 41+3 gestational weeks at a median age of 31+4 gestational weeks. Median fetal weight at stillbirth was 1397 (180-4450)g. Causes of IUFD according to CODAC were congenital fetal malformations in 72 (50.0%) cases; placental pathologies in 26 (18.1%) cases; unknown despite thorough investigation or due to lack of important information in 25 (17.4%) cases; fetal conditions in 9 (6.3%) cases, umbilical cord complications in 6 (4.2%) cases, maternal conditions in 4 (2.8%) cases and IUFD due to infection in 2 (1.4%) cases.
The matched live birth cohort consisted of 138 (55.9%) male and 109 (44.1%) female fetuses born alive between 21+1 and 41+3 gestational weeks at a median age of 31+6 gestational weeks. Median newborn weight at delivery was 1880 (341-4540)g with a median Apgar score of 8 points at 1 minute and 9 points at 5 and 10 minutes, respectively, with a median arterial pH of 7.29 (6.89-7.46). From the five matched live births under 22+0 gestational weeks, case 1 was noted to have a univentricular heart (male, birth weight 482g, Apgar 1/1/1), case 2 had a preterm delivery following premature rupture of membranes (female, 354g, Apgar 2/1/1), case 3 had bilateral kidney agenesis with oligohydramnios (male, 341g, Apgar 1/1/1), case 4 suffered amniotic infection followed by preterm delivery (male, 440g, Apgar 1/0/0) and case 5 had commissural agenesis and vermis hypoplasia (male, 541g, Apgar 2/1/1). None of those extremely premature newborns survived the first 2 weeks of life.