Post Mag Sulfate Therapy in L&D

Jolie, BSN · Jul 5, 2005

I am an RN in L&D at a large teaching hospital. We do quite a large amount of high risk patients, including preterm and preeclamptic mag sulfate patients.
I had heard the other day at work, about a baby we delivered and sent to the NICU, of a mom on Magnesium sulfate prior to delivery, and the infant had a bowel obstruction (on admission to the NICU) due to the magnesium usage during labor. I have never heard of this before, and haven't had a chance to ask any of the perinatologists or neonatalogists about it.
I understand very well how mgso4 works in the mom's body, but I didn't think that very much of it crossed the placenta to the baby - much less, would cause a bowel obstruction.
It really made me wonder, since we tend to use mgso4 like water some days, is this common? Have you seen it before? Should the MD's be informing the moms that this is a potential side effect/undesired outcome in the baby?
Jen
L&D RN

MgSO4 does cross the placenta, but I am not aware of any teratogenic effects of it, especially since it is used primarily in the late 2nd or 3rd trimesters. Infants exposed to high levels of MgSO4 prior to delivery can be depressed, much like narcotic-exposed infants, and require temporary supportive measures such as mechanical ventilation and IV fluids. I have only seen this a handful of times in 11 years of OB and NICU nursing. MgSO4 is a smooth muscle relaxant, so it is possible that it can affect the tone of the infant's GI tract, but to cause an actual obstruction seems unlikely to me.

dawngloves, BSN, RN · Jul 5, 2005

MgSO4 does cross the placenta, but I am not aware of any teratogenic effects of it, especially since it is used primarily in the late 2nd or 3rd trimesters. Infants exposed to high levels of MgSO4 prior to delivery can be depressed, much like narcotic-exposed infants, and require temporary supportive measures such as mechanical ventilation and IV fluids. I have only seen this a handful of times in 11 years of OB and NICU nursing. MgSO4 is a smooth muscle relaxant, so it is possible that it can affect the tone of the infant's GI tract, but to cause an actual obstruction seems unlikely to me.

I know it decreases motility, but an obstruction? I agree. Unlikely.

BittyBabyGrower, MSN, RN · Jul 6, 2005

Yup, mag babies feel like their moms do, it crosses over quite well. As for the bowel obstruction...more likely an ileus. They can last for a while, esp if mom was on a whopper dose of mag. We have had a run of PIH/PET moms lately and lots of sleepy babes, ah I think summer brings it on!

dawngloves, BSN, RN · Jul 6, 2005

You beat me to it BBG. I think they ment ileus, not obstruction.

RNLaborNurse4U · Jul 7, 2005

You beat me to it BBG. I think they ment ileus, not obstruction.

Ah ha! Maybe that's what the infant had. Have you NICU nurses seen ileus in the neonate very often, resulting from large amounts of MgSO4?

Jen

L&D RN

BittyBabyGrower, MSN, RN · Jul 7, 2005

Yep, it does happen...it eventually gets moving again as baby's mag level comes down and we start to feed.

dawngloves, BSN, RN · Jul 7, 2005

I can't remember ever seeing one. We keep our Mag kids NPO until their levels are normal or at least 24 hours.

Jolie, BSN · Jul 7, 2005

I don't recall ever seeing an ileus from MgSO4 either. The only instances I've seen of meconium ileus involved cystic fibrosis.