Is it safe to wear an underwire bra during pregnancy?
Yes. Wearing an underwire bra while you're pregnant shouldn't cause a health problem for you or your baby. But you'll probably find your old underwire bras too constrictive and uncomfortable as you gain weight and your ribcage expands to accommodate your growing uterus.
The concern about wearing an underwire bra during pregnancy stems from the idea that the wire could inhibit blood flow and hamper milk production, which begins well before your baby arrives. But this fear is largely unfounded – in order for your milk production to be affected you would need to be wearing a very tight bra for a long period of time. And there's no real evidence that underwire bras and lactation problems are linked.
That said, many women opt for wire-free bras by the second or third trimester. As your midsection grows, it will begin to rub up against the bottom of the underwire. In fact, many women who plan on breastfeeding switch to wire-free nursing bras at the tail end of their pregnancy, both to prepare for nursing their baby and to provide more room for their expanding breasts.
The bottom line: If your underwire bra is uncomfortable, don't wear it. If it's not, you're fine and not at any risk for bra-related lactation issues.