Controlled intravenous bicarbonate and fetal-maternal acid-base balance. I. The primipara.

The effects of a controlled sodium bicarbonate (SB) infusion on the acid-base balance of the primiparous mother and fetus at labor and delivery were evaluated. Two identical groups of primiparas with normal labor and delivery were studied. According to acid-base parameters observed in the mothers and fetuses of a control group, the pharmacologic dynamics, and the space of distribution of SB, 2 mEq/1 kg of total body weight were administered to the mothers of the study group, beginning at a cervical dilation of 6 cm until full dilation occurred. Highly significant changes in pH, base excess (BE), and plasma bicarbonate were observed in both the mothers and fetuses. In the latter, the significant changes appeared after a time lag of about 2 hours. No adverse effects in the mothers and fetuses were observed. The significant reduction of the relative fetal acidosis by the controlled SB infusion justifies further studies on the therapy potentials of this method in high-risk deliveries and during intrapartum fetal distress.