I've seen it mentioned a few times that thyroid issues can cause a problem with supply...is this only the case for untreated hypo or hyperthyroidism? (And does it occur more with one than the other?)
I do not have a thyroid any longer, so my levels are controlled solely by the amount of hormone replacement I take (Synthroid) - and the medication will have to be adjusted after I give birth, with a possibility of highs and lows during the adjustment period, since going back to a pre-pregnancy dose is just a guess of what my new needs will be.
None of my doctors have ever mentioned that not having a thyroid might affect my ability to breastfeed... (it's role in the pregnancy has been well-addressed through close monitoring/frequent bloodwork and dose adjustments when needed).