Underactive thyroid: will my meds cross into my breast milk?

[blondieminx]

I have an underactive thryoid and am on 75mg levothyroxine every morning. I really want to breastfeed if I can when my baby arrives in January but am not sure whether my medication will cross into my breast milk and dose up the baby too?

If the baby has normal thyroid function, will that in effect cause him/her to become hyperthyroid?

I've got another 3 weeks before my next antenatal appt so I just wondered if any other mumsnetters out there might have the answer?

Thanks all!

toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?LACT

Do a search here, blondieminx, and you'll feel reassured, I think. Share your findings with the doc.

I've been on thyroxine since I was nine and am currently breastfeeding my 8mo and was told it would be absolutely fine.

I think the amount that passes into the milk is miniscule.

Plus you usually take a higher dose of thyroxine when you're pregnant (I was on 250mcg - double my 125mcg normal quantity!) - because the baby depletes your reserves- so the amount you'll be taking afterwards sounds like it'll be minimal. You should be being monitored during your pregnancy - are you?

Double check at your appoint for peace of mind tho obv!

thanks ladies! Yep have consultant led care with blood tests and checkups with thyroid consultant then the obstetrician every 6 weeks. Am only 15 weeks so far - dose has already been upped once.

I knew some clever mumsnetters out there would know, thanks for putting my mind at rest!

Hopefully you're already reassured blondieminx, but just to add I was put on thyroxine for first time when DS about 6months, still breast-feeding, no impact at all. So, fear not!

Just to further put your mind at rest, the way it was explained to me was that the thryroxine is simply replacing what your body should be making naturally and is therefore completely safe when breastfeeding.