title: Durations of second stage of labor and pushing, and adverse neonatal outcomes: a population-based cohort study.
abstract: The associations between duration of second stage of labor, pushing time and risk of adverse neonatal outcomes are not fully established. Therefore, we aimed to examine such relationships.
  
  
  
  A population-based cohort study including 42 539 nulliparous women with singleton infants born in cephalic presentation at ⩾37 gestational weeks, using the Stockholm-Gotland Obstetric Cohort, Sweden, and the Swedish Neonatal Quality Register, 2008 to 2013. Poisson regression was used to analyze estimated adjusted relative risks (RRs), with 95% confidence intervals (CIs). Outcome measures were umbilical artery acidosis (pH <7.05 and base excess <-12), birth asphyxia-related complications (including any of the following conditions: hypoxic ischemic encephalopathy, hypothermia treatment, neonatal seizures, meconium aspiration syndrome or advanced resuscitation after birth) and admission to neonatal intensive care unit (NICU).
  
  
  
  Overall rates of umbilical artery acidosis, birth asphyxia-related complications and admission to NICU were 1.08, 0.63 and 6.42%, respectively. Rate of birth asphyxia-related complications gradually increased with duration of second stage: from 0.42% at <1 h to 1.29% at ≥4 h (adjusted RR 2.46 (95% CI 1.66 to 3.66)). For admission to NICU, corresponding rates were 4.97 and 9.45%, and adjusted RR (95% CI) was 1.80 (95% CI 1.58 to 2.04). Compared with duration of pushing <15 min, a duration of pushing ⩾60 min increased rates of acidosis from 0.57 to 1.69% (adjusted RR 2.55 (95% CI 1.51 to 4.30)).
  
  
  
  Prolonged durations of second stage of labor and pushing are associated with increased RRs of adverse neonatal outcomes. Clinical assessment of fetal well-being is essential when durations of second stage and pushing increases.
authors.affiliation: Clinical Epidemiology Unit, T2, Department of Medicine Solna, Karolinska University Hospital and Institutet, Stockholm, Sweden.|Division of Obstetrics and Gynecology, Department of Women's and Children's Health, Karolinska University Hospital and Institutet, Stockholm, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Sandström
authors.affiliation: Clinical Epidemiology Unit, T2, Department of Medicine Solna, Karolinska University Hospital and Institutet, Stockholm, Sweden.|Istituto Clinico Humanitas, Humanitas University, Rozzano, Milan, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Altman
authors.affiliation: Clinical Epidemiology Unit, T2, Department of Medicine Solna, Karolinska University Hospital and Institutet, Stockholm, Sweden.
authors.forename: S
authors.initials: S
authors.lastname: Cnattingius
authors.affiliation: Clinical Epidemiology Unit, T2, Department of Medicine Solna, Karolinska University Hospital and Institutet, Stockholm, Sweden.|Department of Clinical Science and Education, Karolinska Institutet, Sweden.
authors.forename: S
authors.initials: S
authors.lastname: Johansson
authors.affiliation: Clinical Epidemiology Unit, T2, Department of Medicine Solna, Karolinska University Hospital and Institutet, Stockholm, Sweden.|Department of Obstetrics and Gynecology, South General Hospital, Stockholm, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Ahlberg
authors.affiliation: Clinical Epidemiology Unit, T2, Department of Medicine Solna, Karolinska University Hospital and Institutet, Stockholm, Sweden.|Division of Obstetrics and Gynecology, Department of Women's and Children's Health, Karolinska University Hospital and Institutet, Stockholm, Sweden.
authors.forename: O
authors.initials: O
authors.lastname: Stephansson
mesh_terms: D000138:Acidosis / Q000453:epidemiology*; D000328:Adult; D001238:Asphyxia Neonatorum / Q000453:epidemiology*; D015331:Cohort Studies; D016208:Databases, Factual; D036861:Delivery, Obstetric / Q000379:methods; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal / Q000458:organization & administration; D007748:Labor Stage, Second / Q000502:physiology*; D007744:Obstetric Labor Complications / Q000453:epidemiology*; D010343:Patient Admission; D011247:Pregnancy; D011256:Pregnancy Outcome; D011312:Pressure / Q000009:adverse effects; D012044:Regression Analysis; D012307:Risk Factors; D013548:Sweden; D013997:Time Factors; D014590:Uterine Contraction; D055815:Young Adult