Normal saline IV fluid load decreases uterine activity in active labour

This study was designed to observe the effects of i.v. fluid infusion on uterine activity during normal labour in women receiving an extradural block. Thirty-four women in spontaneous labour at term gestation were allocated randomly and prospectively to one of three i.v. pre-extradural fluid load groups: group A, no fluid load; group B, normal saline 500 ml; and group C, normal saline 1000 ml. Continuous internal measurement of uterine activity was observed before, during and after fluid infusion and extradural block. In groups A and B, uterine activity did not change. In group C, uterine activity decreased after infusion of saline (P < 0.01) and returned to baseline over the next 20 min. Extradural block was not associated with a change in uterine activity. Hypotension was not increased in the group that received no fluid preload.