Increased Risk of Peripartum Perinatal Mortality in Unplanned Births Outside an Institution: A Retrospective Population-Based Study

Abstract

BACKGROUND: Births in midwife-led institutions may reduce the frequency of medical interventions and provide cost-effective care, while larger institutions offer medically and technically advanced obstetric care. Unplanned births outside an institution and intrapartum stillbirths have frequently been excluded in previous studies on adverse outcomes by place of birth. OBJECTIVE: The objective of the study was to assess peripartum mortality by place of birth and travel time to obstetric institutions, with the hypothesis that centralization reduces institution availability but improves mortality. STUDY DESIGN: This was a national population-based retrospective cohort study of all births in Norway from 1999 to 2009 (n ¼ 648,555) using data from the Medical Birth Registry of Norway and Statistics Norway and including births from 22 gestational weeks or birthweight 500 g. Main exposures were travel time to the nearest obstetric institution and place of birth. The main clinical outcome was peripartum mortality, defined as death during birth or within 24 hours. Intrauterine fetal deaths prior to start of labor were excluded from the primary outcome. RESULTS: A total of 1586 peripartum deaths were identified (2.5 per 1000 births). Unplanned birth outside an institution had a 3 times higher mortality (8.4 per 1000) than institutional births (2.4 per 1000), relative risk, 3.5 (95% confidence interval, 2.5e4.9) and contributed 2% (95% confidence interval, 1.2e3.0%) of the peripartum mortality at the population level. The risk of unplanned birth outside an institution increased from 0.5% to 3.3% and 4.5% with travel time <1 hour, 1e2 hours, and >2 hours, respectively. In obstetric institutions the mortality rate at term ranged from 0.7 per 1000 to 0.9 per 1000. Comparable mortality rates in different obstetric institutions indicated well-functioning routines for referral. CONCLUSION: Unplanned birth outside an institution was associated with increased peripartum mortality and with long travel time to obstetric institutions. Structural determinants have an important impact on perinatal health in high-income countries and also for low-risk births. The results show the importance of skilled birth attendance and warrant attention from clinicians and policy makers to negative consequences of reduced access to institutions.

Association between travel time to delivery unit and unplanned out‐of‐hospital birth, infant morbidity and mortality: A population‐based cohort study

“…Deaths during the neonatal period may be due to a combination of factors including fetal medical conditions, maternal medical and sociodemographic conditions and lack of monitoring and interventions during pregnancy, labor and after birth. Some previous studies have shown associations between increasing travel time and out-of-hospital birth 3,14,17,28 and subsequent risk of infant mortality, 3,14,15,17,29 whereas others have not. 18,19 It's possible that reports from less recent studies, including births from the 1950s to the early 1990s, that increasing travel time did not change the outcome of infant death, 18,19 could be due to the fact that the available quality of care of newborns at the time did not contribute to significant reductions of infant mortality overall, as in present times.…”

“…The Norwegian study created travel zones through GIS analyses based on coordinates for registered home addresses and the nearest delivery unit within a given time limit. 14 The proportion of individuals >2 hours from the nearest delivery unit in Norway was 0.9%, and unplanned out-ofhospital birth 0.7%. These numbers are very similar to those found in our study (1% and 0.6%, respectively).…”

“…Travel times were split into three categories: 0-30 minutes, 31-60 minutes and ≥61 minutes, to compare the results with similar studies from other Nordic countries. 14 The underlying assumption for deriving travel times is that the traveler drives without a stop along the shortest route at the maximum allowed speed. Less than 0.3% of the women (n = 970) could not be routed to a destination and were excluded from the analysis because home address and delivery unit were separated by water bodies and not connected via bridges or tunnels.…”

“…7 A recent study from Norway showed that the risk of unplanned out-of-hospital birth increased with increasing travel time, and that unplanned out-of-hospital births had a three times higher risk of peripartum mortality compared with births at a delivery unit. 14 Studies from Finland showed that perinatal mortality rates from unplanned out-of-hospital births were five 3 to six 15 times higher than for those who delivered in hospitals. In studies of rural parturient women in Canada, a travel time of 1-2 hours to maternity services was associated with a six times higher likelihood of an unplanned out-of-hospital birth, and a travel time of more than 4 hours was associated with a three times higher likelihood of perinatal mortality.…”

“…Furthermore, closure of delivery units may increase travel time for certain pregnant and laboring women 7 . A recent study from Norway showed that the risk of unplanned out‐of‐hospital birth increased with increasing travel time, and that unplanned out‐of‐hospital births had a three times higher risk of peripartum mortality compared with births at a delivery unit 14 . Studies from Finland showed that perinatal mortality rates from unplanned out‐of‐hospital births were five 3 to six 15 times higher than for those who delivered in hospitals.…”