At this time there isnt any research to say there is or isnt harm. I would hazard a guess that its unlikely to be a problem. Especially if the bleaching product you are using is hydrogen peroxide. As HP is unstable it breaks down into oxygen and water, and is not likely to be entering your blood stream and your milk supply. Carbamide peroxide an alternative bleaching agent breaks down into HP and Urea. Again I cant see these passing through the stomach and effecting your milk, but there is more of a question mark on CP.
Also considering that peroxide is actually found in breast milk , again i would imagine there is little to no risk
http://www.ncbi.nlm.nih.gov/pubmed/1...ubmed_RVDocSum
The manufacturers are likely to be covering themselves in case of a spurious law suit.
Still, given the lack of research, use it at your own risk. I tend to advise pregnant mothers to avoid unnecessary dental procedures. Its not so much for the risk to the baby, but for peace of mind of the mother. If something bad happens, there is a tendency for a mum (especially a new mum ) to blame themselves for anything they did.
Really the only problems I could forsee are increased sensativity due to the mild acidity of the peroxide, especially if you have any holes in your teeth, or worn enamel.
The other possibility is that this is an over the counter whitening job. If so, the peroxide levels are so low as to be mostly ineffective anyway. So considering most of my advice would be tailored to 10% or 20% Carbamide Peroxide, then the over the counter stuff will be way lower and even less of an issue.
Hope that helps, probably made it more confusing with all that!
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