Joy, Jean, et al.,

I so appreciate everyone's input to my original post seeking references for supporting the theory of maternal IV use during labor and potentially 'over hydrated' infants at birth to which we may attribute some cases of excessive weight loss.

I've read all the references forwarded to me, texts, etc., and thanks to Joy finally got my hands on that Dahlenberg reference which has often been cited! I love 'my' internet as my husband puts it! 

Earlier this week Joy wrote, 

"At this point, there is no clear evidence of an association between neonatal
weight loss and maternal IV fluids, but we are closer to showing that there
are non feeding factors related to weight loss and that there may be weight
loss that is a correction not cause for concern." I'm not sure everyone reading caught
that comment.
There has been some current published research that better explains the processes that most influence the maternal transfer of fluid to the fetus. I have a summary below. Although diffusion and osmosis are part of the process as you will see upon reading 
Faber's article, there are other influencing factors that participate in the overall regulation of fetal fluid volume. 

The author of this article from the International Journal of Developmental Biology, The Placenta in the Integrated Physiology of 
Fetal Volume Control graciously dialogued with me via e-mail and after explaining the theory, in his opinion he believes 
there is no theoretical foundation for suspecting maternal IV would result in increased hydration of the fetus and excessive
diuresis following birth.

In his article Faber writes "...water flows into the fetus through the placenta since little water is exchanged at any other
interface between mother and conceptus. But trans-placental water flow is modulated by the fetal kidneys (emphasis mine). 
The kidneys are not masters either, for they take their cue from the fetal arterial pressure. Arterial pressure in its
turn depends on fetal vascular resistance and that, in turn, depends on the fetal somatic blood flow, generated by the
fetal heart." He also writes, "The placenta does not control the amount of water that enters the conceptus;nor does any 
other single fetal structure. And water entry is not dependent on the volume of water already present. However
the combined physiological properties of the fetal heart, kidneys, somatic tissues and placenta constitute a consistent 
explanation of fetal water volume control."

After reading all of this literature, for me, and like Joy stated, I feel confident concluding that there really is not any strong 
or sufficient evidence at this time to support a claim that maternal IV fluid is significantly diffused to the infant, thus inflating
the birth weight due to over hydration. I have read over a dozen articles and then went on to locate the original cited references
that address this theory. The association between epidural use and a .05% increase in weight loss within the first 2-2.5 days does
not control for influencing factors such as the demonstrated fewer feeds that infants born to mothers who have epidurals may
experience, the maternal IV that accompanies the epidural, the pitocin which may or may not accompany the epidural etc.or
distinguish between epidural anesthesia and mode of delivery as in some cases epidurals may be used for both vaginal or 
cesarean birth. Making it premature to attribute this factor directly to maternal IV. 

Thanks for the great dialogue!

Michelle H. Kinne BA IBCLC RLC ICCE CD(DONA)





 
 
 
 
 
 

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