Seizures in newborn infants without hypoxic ischemic encephalopathy - antenatal and labor-related risk factors: a case-control study

Objective: To identify antepartum and intrapartum risk factors for neonatal seizures in the absence of hypoxic ischemic encephalopathy (HIE). Methods: Population-based case-control study. Of 98 484 births, 40 newborns at 34 gestational weeks or later had seizures within the first 7 days of life. Cases (n = 40) and controls (n = 160) were retrieved from the University hospitals of orebro for 1994-2013 and Uppsala for 2003-2013. Demographics and characteristics of pregnancy, labor, delivery, and neonatal data were analyzed. Crude odds ratio (OR) and adjusted odds ratios (AOR) with 95% confidence intervals (CIs) for antenatal and intrapartum factors were calculated using logistic regression analysis. Main outcome measure was neonatal seizures within the first 7 days of life. Results: The incidence of neonatal seizures without HIE was 0.41/1000 live births. Antenatal risk factors for neonatal seizures were as follows: short maternal stature (AOR: 5.4; 1.8-16.5); previous caesarean section (AOR: 4.8; 1.5-15.0); and assisted fertilization (AOR: 6.8; 1.3-35.2). Intrapartum risk factors were as follows: induction of labor (AOR: 5.7; 1.8-17.7); preterm birth (AOR: 13.5; 3.7-48.9); and head circumference >37 cm (AOR: 6.9; 1.4-34.8). Conclusions: Preterm birth was the strongest risk factor for neonatal seizures in the absence of HIE. The results also indicate that feto-pelvic disproportion is associated with the occurrence of seizures. Rationale: Antepartum and intrapartum risk factors for newborn seizures in the absence of HIE were investigated in a case-control study. Out of 98 484 births at 34 gestational weeks or more, 40 newborns had seizures without HIE. All had a normal Apgar score although they later presented with seizures. Preterm birth was the strongest risk factor (OR: 13.5; 95% CI: 3.7-48.9). Our results also indicate that feto-pelvic disproportion is of importance. Furthermore, a history of prior caesarean was associated with seizures. This is the first study to assess obstetric risk factors for newborn seizures separate from those with seizures and concomitant HIE. The distinction is of importance due to different etiologies, treatments, and preventive strategies.