Time of birth and risk of neonatal death at term: retrospective cohort study.
OBJECTIVE
To determine the effect of time and day of birth on the risk of neonatal death at term.


METHODS
Population based retrospective cohort study.


METHODS
Data from the linked Scottish morbidity records, Stillbirth and Infant Death Survey, and birth certificate database of live births in Scotland, 1985-2004.


METHODS
Liveborn term singletons with cephalic presentation. Perinatal deaths from congenital anomalies excluded. Final sample comprised 1,039,560 live births.


METHODS
All neonatal deaths (in the first four weeks of life) unrelated to congenital abnormality, plus a subgroup of deaths ascribed to intrapartum anoxia.


RESULTS
The risk of neonatal death was 4.2 per 10,000 during the normal working week (Monday to Friday, 0900-1700) and 5.6 per 10 000 at all other times (out of hours) (unadjusted odds ratio 1.3, 95% confidence interval 1.1 to 1.6). Adjustment for maternal characteristics had no material effect. The higher rate of death out of hours was because of an increased risk of death ascribed to intrapartum anoxia (adjusted odds ratio 1.7, 1.2 to 2.3). Though exclusion of elective caesarean deliveries attenuated the association between death ascribed to anoxia and delivery out of hours, a significant association persisted (adjusted odds ratio 1.5, 1.1 to 2.0). The attributable fraction of neonatal deaths ascribed to intrapartum anoxia associated with delivery out of hours was 26% (95% confidence interval 5% to 42%).


CONCLUSIONS
Delivering an infant outside the normal working week was associated with an increased risk of neonatal death at term ascribed to intrapartum anoxia.
Pasupathy
Dharmintra
D
Department of Obstetrics and Gynaecology, University of Cambridge, and NIHR Cambridge Comprehensive Biomedical Research Centre, Cambridge CB2 2SW.
Wood
Angela M
AM
Pell
Jill P
JP
Fleming
Michael
M
Smith
Gordon C S
GC
D039602:After-Hours Care / Q000592:standards* / Q000706:statistics & numerical data; D002423:Cause of Death; D005260:Female; D005311:Fetal Hypoxia / Q000401:mortality / Q000628:therapy*; D006801:Humans; D007226:Infant Mortality; D007231:Infant, Newborn; D008423:Maternal Age; D010298:Parity; D018743:Perinatal Care / Q000592:standards* / Q000706:statistics & numerical data; D011247:Pregnancy; D012189:Retrospective Studies; D012307:Risk Factors; D012606:Scotland / Q000453:epidemiology; D012959:Socioeconomic Factors; D050497:Stillbirth / Q000453:epidemiology; D013997:Time Factors