Hyperthyroidism, pregnancy, and breastfeeding

Hi all,
This is more a question about hyperthyroidism than diabetes, but I know they often go hand in hand, so here goes. I just found out that I have hyperthyroidism. I'm wondering if any of you have gone through pregnancy or breastfeeding while on antithyroid meds. (I'm currently breastfeeding and starting to think about #2). Also wondering if you have found that hyperthyroidism affects your blood sugar control. I think it is the reason I've been seeing my insulin needs increase recently.

If anyone would like to share their experiences, I'd love to hear them.


Hi. I take synthroid (have for about 4 years) and have a 12 month old son and am due again on Halloween. I breastfed my son - the doc said it was fine. During preg my synthroid dosage increased a lot (as it should) and went back to my pre-preg dosage after. My dosage is increasing this pregnancy the same amount as last. My insulin dosage wwent from 20 units lantus a day and about 8 units of apidra per meal to about 42lantus a day and about 20 units apridra per meal. And it decreased immediately after having the baby to pre preg dosage. I noticed in this 2nd preg that my insulin dosage needed to be increased a lot quicker so far than with preg#1. My synthroid dosage increaed the same rate (maybe being I only tested it every 5 wks).
When I first started taking synthroid I noticed that my insulin (novolog at the time) seemed to take a lot longer (very long) to kick in and then I would take a quick fall. I switched to apidra and that seemed to help (or maybe my body jus needed to get adjusted, I’m not sure). But pregnancywise, other than the dose increase, which is nornal, I didn’t notice any other affects of taking synthroid.
Good luck w baby#2!

After doing some internet reading, I see that postpartum hyperthyroidism is fairly common and sometimes not permanent. I'll see an endocrinologist on Wednesday, so we'll see whether he thinks this is permanent for me or not.

SS, you must be hypothyroid. Synthroid is apparently safer than the drugs for hyperthyroidism.

Oops, yes I didn’t realize you were talking about hyper, not hypo. Good luck at your doctor appointment.

I have both diabetes and hyperthyroid. Have had Type 1 diabetes since 1995 and hyperthyroid since 2005. I was taking PTU for hyperthyroid during my 1st pregnancy and I also exclusively breastfed for 12 months while taking PTU. It didn't harm my baby at all she is strong and healthy today at 4 years old! I'm pregnant with #2 now and still taking PTU, no problems at all! Uncontrolled hyperthyroidism did affect my blood sugars but that was when I didn't know I had it, once they discovered it and put me on the PTU my blood sugars went back down and was well controlled again. I hope that helps!

Thanks, Carolyn. That's good to hear. It turns out I do have Graves', and my endo put me on methimazole, because of the small risk of liver failure with PTU. He assures me it's fine to take while breastfeeding, but my daughter's pediatrician isn't so sure... they did say they'd put me on PTU when we start trying for the next baby. But I wonder if I should just go ahead and take PTU now.

Yeah I would say start PTU now if you are planning on having another. The risk of liver failure is sooo small and my doctor said that such a small amount is passed to the baby that it wouldn't affect the baby at all.

I guess I'll stick with the methimazole for now. I haven't even gotten my period back yet, so it will be awhile before we start thinking about #2.