Perinatal mortality and severe morbidity of term infants

Abstract

This thesis describes the various aspects of perinatal morbidity and mortality in term infants. Most children are born at a gestational age of more than 36 completed weeks. Their chances of survival are high (99.7%). However, more than a quarter of perinatal deaths occur among births from 37 weeks’ gestation onwards. The perinatal mortality of term infants in the Netherlands in 2008 was 2.7 per 1000 term infants, of which 60% occurred in the antenatal period. To obtain more insight in mortality and severe morbidity of term infants, we started a prospective study in 2007. During a two-year period, all cases of perinatal mortality and morbidity were collected in the in the catchments area of the Neonatal Intensive Care Unit (NICU) of the University Medical Center Utrecht. The first aim of this study was to improve the quality of obstetric care by organising perinatal audits of all cases of perinatal mortality and severe morbidity of term infants without severe congenital malformation. The second aim was to gain insight into perinatal mortality and severe morbidity in relation to the Dutch obstetric care system. The results of this study are described in this thesis. In part I of this thesis we focused on perinatal morbidity and mortality among term infants in relation to the Dutch obstetrical care system. In total the perinatal death rate was 2.6 per 1000 infants delivered. We found that infants of pregnant women at low risk whose labour started in primary care under supervision of a midwife had a higher risk (RR 2.3, CI 1.1 to 4.8) of delivery related perinatal death compared with infants of pregnant women at high(er) risk whose labour started in secondary care under the supervision of an obstetrician. Inparticular,infantsofwomen whowerereferredfromprimaryto secondarycare duringlabour had morethan3.5-foldhigher (RR 3.7,CI 1.6 to 8.5)perinataldeathratecomparedtoinfantsofwomen whostartedlabourinsecondarycare. With respect to severe morbidity in normal term infants we found no difference between the low risk and high risk pregnancies. However, in the group of low risk women referred during labour from primary care to secondary care, the risk of NICU admission and asphyxia was significant higher compared to high(er)-risk women who started labour in secondary care. These findings are unexpected but seriously questions the supposed effectiveness of the Dutch obstetric system that is based on risk selection and obstetric care at two levels.In part II of this thesis we focused on the results of the perinatal audits. We found a possible or probable relation between substandard care factors and term stillbirths, perinatal asphyxia or perinatal infection in respectively 27%, 58% and 37% of all cases. To improve outcome, knowledge of the cause of perinatal mortality or morbidity is crucial. The underlying cause of death in the ATNICID study, based on the Tulip classification system, in term stillbirths, intrapartum deaths and neonatal deaths was respectively in 72%, 55% and 53% due to placental pathology