Outcome of small for gestational age-fetuses in breech presentation at term according to mode of delivery: a nationwide, population-based record linkage study.

PURPOSE: To evaluate whether a trial of planned vaginal labor is associated with adverse perinatal outcome in singleton, small for gestational agefetuses in breech presentation at term.

METHODS: This is a Finnish nationwide, population-based record linkage study. The studied population included all small for gestational age breech labors from January 1, 2004 to December 31, 2014. "Small for gestational age" was defined as birth weight below the 10th percentile according to gestational age. An odds ratio with 95% confidence intervals was used to estimate the relative risk for perinatal mortality and morbidity in a trial of vaginal labor. The reference group included all small for gestational age infants born in breech presentation by planned cesarean section.

RESULTS: During the study period of eleven years, 1841 small for gestational age infants were delivered in breech position at term. A trial of vaginal breech labor is associated with a higher rate of neonates with an umbilical pH below seven [odds ratio 7.82 (1-61.21)], a lower 5-min Apgar score < 7 [adjusted odds ratio 6.39 (1.43-28.46)] and < 4 [adjusted odds ratio 6.39 (1.43-28.46)], a higher rate of postpartum neonatal intubations [adjusted odds ratio 6.52 (1.93-22)], an increased rate of neonatal antibiotic therapy [adjusted odds ratio 3.31 (1.85-5.93)], and with a higher rate of combined severe adverse perinatal outcome [adjusted odds ratio 4.24 (1.43-12.61)].

CONCLUSION: A trial of vaginal breech labor in SGA fetuses is associated with adverse perinatal outcome and should be avoided.