[Intrapartum asphyxia: Risk factors and short-term consequences]

Intrapartum asphyxia is a rare yet serious complication during labor with immediate consequences and possible long-term neurological impairment. The international Cerebral Palsy Task Force established criteria that attribute a cerebral palsy to intrapartum asphyxia: metabolic acidemia measured at birth with pH<7 and base deficit≥12mmol/L.

To determine the risk factors of an intrapartum asphyxia occurring in term live births, to evaluate the short-term consequences.

Our retrospective study included all births between 2002 and 2010 in a level 3 maternity of a university hospital center. Inclusion criteria were those of the Cerebral Palsy Task Force associated with a gestational age≥34weeks of gestation. We studied the conventional markers of intrapartum asphyxia: Apgar score at 5minutes, abnormal cardiotogographic recordings whether they occurred after a sentinel hypoxic event or not before and during labor. The duration of expulsive efforts, the amniotic fluid aspects, the delivery mode as well as the preexisting pregnancy pathologies were also evaluated. On the other hand, we studied the short-term consequences at the newborns: death, multiorgan failure and especially the occurring of a neonatal encephalopathy using Sarnat and Sarnat staging.

One hundred and twenty-nine newborns (0.43%) out of 29,416 live births had a pH<7 of whom only 82 (0.27%) presented a real intrapartum asphyxia and were included in this study. A preexisting pregnancy pathology was found in 22% of the women. Hypoxic events were noted in only 9/82 of the cases. Abnormal cardiotocographic recordings were present in 97.6% of the cases. The duration of expulsive efforts as well as the amniotic fluid aspects did not interfere with the occurring of a metabolic acidemia. Caesarean rate was at 46.3% and instrumental extraction rate was at 34.1%. Thity-eight newborns (46.3%) were admitted in neonatal intensive care in which we noted 3 deaths (3.65%), 2 multiorgan failures (2.4%) and 17 neonatal encephalopathy (20.7%). The pH value seemed to influence the occurring of an encephalopathy: 50% when pH<6.9 vs. 13.6% when pH≥6.9 (P=0.0013), as well as for the base deficit: 50% when BD<-18 vs. 15.7% when BD≥-18 (P=0.0068). Apgar score at 5minutes also seemed predictive for a neonatal encephalopathy: 100% when<4, 46% between 4 and 6 and 11% when>6 (P<0.001).

Our results showed an intrapartum asphyxia rate half the one widely recorded of 0.5% of total live births. Our study also validates the commonly used markers to evaluate a high risk of an early neonatal encephalopathy. This study should be continued with the evaluation of hypoxia long-term consequences on the psychomotor development of these kids and especially the occurring of cerebral palsy.