Outcomes in children after mild neonatal hypoxic ischaemic encephalopathy: A population-based cohort study.

OBJECTIVE: To investigate whether mild neonatal hypoxic ischaemic encephalopathy (HIE) in term born infants is associated with cerebral palsy, epilepsy, mental retardation and death up to 6 years of age. DESIGN: Population-based cohort study. SETTING: Sweden, 2009-2015. POPULATION: Live term born infants without congenital malformations or chromosomal abnormalities (n = 505 075). METHODS: Birth and health data were retrieved from Swedish national health and quality registers. Mild HIE was identified by diagnosis in either the Swedish Medical Birth Register or the Swedish Neonatal Quality Register. Cox proportional hazards regression was used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs). MAIN OUTCOME MEASURES: A composite of the outcomes cerebral palsy, epilepsy, mental retardation and death up to 6 years of age. RESULTS: Median follow-up time was 3.3 years after birth. Of 414 infants diagnosed with mild HIE, 17 were classified according to the composite outcome and incidence rates were 12.6 and 2.9 per 1000 child-years in infants with and without HIE respectively. Infants with mild HIE was four times as likely to be diagnosed with the composite outcome (HR 4.42, 95% CI 2.75-7.12) compared with infants without HIE. When analysed separately, associations were found with cerebral palsy (HR 21.50, 95% CI 9.59-48.19) and death (HR 19.10, 95% CI 7.90-46.21). HRs remained essentially unchanged after adjustment for covariates. CONCLUSIONS: Mild neonatal HIE was associated with neurological morbidity and mortality in childhood. Challenges include identifying infants who may develop morbidity and how to prevent adverse outcomes.

Hypoxic ischemic encephalopathy in offspring of immigrant women in Sweden: A population-based cohort study.

INTRODUCTION: One in four women giving birth in Sweden is foreign-born. Immigrant status has been suggested as a risk factor for adverse perinatal outcomes. It is not known if infants to foreign-born women have an increased risk of severe birth asphyxia, or which factors might mediate such association. MATERIAL AND METHODS: A population-based cohort study of 726 730 live births at 36 weeks of gestation or more in Sweden in 2009-2015. The exposure was maternal country of birth, grouped according to the World Bank country classification: low-, lower-middle, upper-middle, and high-income economies. The main outcome was neonatal hypoxic ischemic encephalopathy (HIE). The outcome was estimated by severity and classified as non-hypothermia-treated HIE, representing mainly mild cases, and hypothermia-treated HIE, representing moderate to severe cases. A secondary outcome was low Apgar score at 5 minutes, defined as <7 or <4. Odds ratios with 95% CI were calculated, using Swedish-born women as the reference. Structural equation modeling was used to investigate potential mediation of known antepartum risk factors. RESULTS: A total of 854 infants were diagnosed with HIE and 398 received therapeutic hypothermia. Offspring of mothers born in low-income countries had the highest incidences of HIE and low Apgar score, with an incidence of therapeutic hypothermia of 1.1 per 1000. Compared with offspring of Swedish-born mothers, these neonates had an almost two-fold increased risk of HIE, with or without hypothermia treatment (odds ratio 1.7; 95% CI 1.2-2.7 and odds ratio 1.7; 95% CI 1.2-2.6, respectively), and a 2- to 3-fold increased risk of low Apgar score. The structural equation model analysis indicated an exclusive direct effect of country of birth on HIE. Factors reflecting socio-economic status mediated a small proportion of the risk of Apgar score <7 at 5 minutes. CONCLUSIONS: Offspring of women born in low-income countries had associations with severe birth asphyxia, with increased risk of both HIE and low Apgar score at 5 minutes. The associations seemed only to be marginally mediated by other antepartum factors. The associations are complex and further studies are needed to find explanatory and potentially preventable factors.

Time matters-a Swedish cohort study of labor duration and risk of uterine rupture.

INTRODUCTION: Uterine rupture is an obstetric emergency associated with maternal and neonatal morbidity. The main risk factor is a prior cesarean section, with rupture occurring in subsequent labor. The aim of this study was to assess the risk of uterine rupture by labor duration and labor management. MATERIAL AND METHODS: This is a Swedish register-based cohort study of women who underwent labor in 2013-2018 after a primary cesarean section (n = 20 046). Duration of labor was the main exposure, calculated from onset of regular labor contractions and birth; both timepoints were retrieved from electronic medical records for 12 583 labors, 63% of the study population. Uterine rupture was calculated as events per 1000 births at different timepoints during labor. Risk estimates for uterine rupture by labor duration, induction of labor, use of oxytocin and epidural analgesia were calculated using Poisson regression, adjusted for maternal and birth characteristics. Estimates were presented as adjusted rate ratios (ARR) with 95% confidence intervals (CI). RESULTS: The prevalence of uterine rupture was 1.4% (282/20 046 deliveries). Labor duration was 9.88 hours (95% CI 8.93-10.83) for women with uterine rupture, 8.20 hours (95% CI 8.10-8.31) for women with vaginal delivery, and 10.71 hours (95% CI 10.46-10.97) for women with cesarean section without uterine rupture. Few women (1.0/1000) experienced uterine rupture during the first 3 hours of labor. Uterine rupture occurred in 15.6/1000 births with labor duration over 12 hours. The highest risk for uterine rupture per hour compared with vaginal delivery was observed at 6 hours (ARR 1.20, 95% CI 1.11-1.30). Induction of labor was associated with uterine rupture (ARR 1.54, 95% CI 1.19-1.99), with a particular high risk seen in those induced with prostaglandins and no risk observed with cervical catheter (ARR 1.19, 95% CI 0.83-1.71). Labor augmentation with oxytocin (ARR 1.60, 95% CI 1.25-2.05) and epidural analgesia (ARR 1.63, 95% CI 1.27-2.10) were also associated with uterine rupture. CONCLUSIONS: Labor duration is an independent factor for uterine rupture among women attempting vaginal delivery after cesarean section. Medical induction and augmentation of labor increase the risk, regardless of maternal and birth characteristics.