I have no links to share on this, but I'll bet mwherbs does...I have heard however, that there is no evidence to show that this procedure changes outcomes. It was also done to me at my one hospital birth 9yrs ago (last baby, first hospital birth/csec after all other homebirths). I agreed to it since in theory it sounded good and my waters were 'pea soup'. Only years later did I hear that there is no evidence to support the practice. The idea is that by removing the mec, the baby is less likely to aspirate any of it into the lungs.
The thing with mec is that while a fair amount of babes do pass mec in utero, few of them aspirate it--or aspirate enough to cause problems. But most hosp providers look upon mec with dread because it CAN cause big problems for babies--from what I have seen myself, there seems to be little by way of middle ground: most babies by far are ok with mec in the water, but rarely, a baby does aspirate enough of it to cause serious illness or even death.
To me, saline replacement seems like one of those things that med ppl 'do', because they need to 'do' something, even something of no use--to control what is uncontrollable and their own fear. If the mec is 'old', for instance (at least a couple of days if not weeks), then it could well already be too late for saline replacement. It *could* be that there was a cord accident or something else leading to oxygen deprivation that prompted the baby to pass mec and then to gasp for breath, sucking in the mec. If there is mec already in the baby's lungs, saline replacement will have very little if any impact on outcome--the baby's fate then rests on it's own strength, on the amount of mec present in lungs, and on protective measures taken after birth (suctioning and resp. therapy, for instance).
With 'too much' mec--essentially filling lungs or entirely clogging trachea--it may already be too late because too much time could pass between removing mec/opening airway and actually getting oxygen into the baby. This is especially true since in the presence of mec, most often in hospitals the cord is immediately cut, thus necessitating that the baby get oxygen through its lungs since none is coming thru umb. cord anymore. With a lesser amount of mec in lungs/trachea, then those measures for suctioning and respiratory therapy after the birth could well be plenty for that babe's health. If baby is still strong (not already too brain damaged from original incident in utero that led to mec aspiration in the first place), baby will try to breathe, heart will beat for several minutes even w/out oxygen, a struggle for survival will ensue that are most likely to be helped by med intervention. If baby is already 'gone' in terms of brain damage from original incident--but mainly only living on the 'life support' provided by placenta/cord while in utero--then there will be very little or no efforts made by baby toward survival.
Again, that extreme possibility is pretty remote--MOST babies w/mec in water do FINE.
I haven't provided anything solid on the saline replacement--I hope another of the birth professionals will since I too, would like to see research on this.
