Maternal arterial blood values during delivery: effect of mode of delivery, maternal characteristics, obstetric interventions and correlation to fetal umbilical cord blood

Abstract

1 Maternal arterial blood values during delivery: effect of mode of delivery, maternal 2 characteristics, obstetric interventions and correlation to fetal umbilical cord blood 3 4 Mehreen Abstract 27 Objective 28 To determine a reference interval for maternal arterial blood values during vaginal delivery and 29 to elucidate the effect of common maternal characteristics and obstetric interventions on 30 maternal acid base values during vaginal and planned cesarean section (CS). 31 Design 32 Prospective, observational study of randomly selected women undergoing vaginal deliveries 33 and planned CS at Skåne University Hospital, Malmö, Sweden. Results35 Two hundred and fifty women undergoing vaginal delivery (VD) and fifty-eight women 36 undergoing planned CS were recruited. We found significant differences for gestational age, 37 parity, artery pH, pCO 2 , pO 2 , sO 2 and cord venous pH, pCO 2 and lactate between the two study 38 groups (P < 0.005). For women undergoing vaginal delivery, we found significant changes in 39 base deficit, hemoglobin, bilirubin, potassium, glucose and lactate values as compared to 40 women with planned CS (P < 0.02). Maternal characteristics did not significantly affect acid 41 base parameters however, multiple regression showed significant associations for the use of 42 epidural anesthesia on maternal pH (P < 0.05) and pO 2 (P < 0.01); and synthetic oxytocin on 43 pCO 2 (P = 0.08), glucose (P < 0.00) and lactate (P < 0.02) in maternal blood. Maternal arterial 44 pH, pCO 2 and lactate correlated significantly to values in venous umbilical cord blood (P < 45 0.000). Conclusions47 Reference values for maternal arterial blood gases in vaginal deliveries for term pregnancies 48 were outlined and we found that most arterial blood gas parameters varied significantly 3 49 according to mode of delivery. The use of different obstetrical interventions like epidural 50 anesthesia or synthetic oxytocin, resulted in significant changes in blood gas values. 51 Introduction52 It is well known that there are significant changes in almost all maternal organ systems during 53 pregnancy and that these physiological changes enable the mother to optimally nourish the fetus 54 as well as prepare her for labor (1). Klajnbard and Maguire (2, 3) showed large variations in 55 most maternal venous parameters during the three trimesters of pregnancy. Despite this 56 knowledge, obstetricians routinely use reference values from non-pregnant women to assess 57 the condition of the pregnant patient. Few studies have focused on physiological variations 58 during pregnancy and delivery, and arterial blood gases including electrolytes, bilirubin, 59 glucose and lactate have seldom been studied. In addition, the possible impact of mode of 60 delivery on different maternal and obstetric factors commonly encountered during delivery, has 61 not been studied.62 One of the most frequently encountered maternal risk factors during pregnancy and delivery is 63 obesity. Maternal obesity is associated with increased fat deposition,...