Risk of eclampsia or HELLP-syndrome by institution availability and place of delivery - A population-based cohort study.

OBJECTIVE: To examine the association between availability of obstetric institutions and risk of eclampsia, HELLP-syndrome, or delivery before 35 gestational weeks in preeclamptic pregnancies. STUDY DESIGN: National population-based retrospective cohort study of deliveries in Norway, 1999-2009 (n = 636738) using data from The Medical Birth Registry of Norway and Statistics Norway. Main exposures were institution availability, measured by travel time to the nearest obstetric institution, and place of delivery. We computed relative risks (RR) with 95% confidence intervals (CI) using travel time ≤1 h as reference. We stratified analyses by parity and preeclampsia, and adjusted for socio-demographic and medical risk factors. Successive deliveries were linked using the national identification number. RESULTS: We identified 1387 eclampsia/HELLP cases (0.2%) and 3004 (0.5%) deliveries before 35 weeks in preeclamptic pregnancies. Nulliparous women living >1 h from any obstetric institution had 50% increased risk of eclampsia/HELLP (0.50 versus 0.35%, adjusted RR 1.5; 95 %CI 1.1-1.9). Parous women living >1 h from emergency institutions had a doubled risk of eclampsia (0.6‰ versus 0.3‰, adjusted RR 2.0; 1.2-3.3). Women without preeclampsia in the present pregnancy or history of preeclampsia constituted all eclampsia/HELLP cases in midwife-led institutions, 39-50% of cases in emergency institutions, and 78% of cases (135/173) in subsequent deliveries. Women with risk factors delivered in the emergency institutions, indicating well-implemented selective referral. CONCLUSION: The study shows the importance of available obstetric institutions. Policymakers and clinicians should consider the distribution of potential benefits and burdens when planning and evaluating the obstetric health service structure.

Increased risk of peripartum perinatal mortality in unplanned births outside an institution: a retrospective population-based study.

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 = 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, 2.5-4.9) and contributed 2% (95% confidence interval, 1.2-3.0%) 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, 1-2 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.