Green MP Julie Anne Genter has shared an "incredibly insensitive" email she received from a member of the public.
The email, posted to Facebook, appeared to blame Ms Genter's tragic miscarriages on fluoride in the water supply.
"I read in the paper a little while ago that you had two miscarriages," it reads. "Therefore I thought I would send you this information on fluoride. People don't realise how toxic fluoride is, even at low levels.
"I presume that is because the dentists will be extremely embarrassed if it is found that they are wrong."
The email goes on to say "more and more research" is being conducted, and there is "no need to have it in the water".
"Children need to be taught to brush their teeth and parents need to keep them off soft drinks."
Ms Genter, 37, revealed to the New Zealand Women's Weekly in March that she has experienced two miscarriages, both in recent years.
"I'm quite a rational person and thought I could tell myself it simply wasn't meant to be, but I was surprised at how intensely powerful my emotions were," she told the magazine.
"It was upsetting and very sad."
Ms Genter told Newshub on Saturday she couldn't believe how badly worded the email was, regardless of the sender's intentions.
"I was surprised and fairly offended. My reaction was also to laugh about it. I'm sure the person who sent it was well-meaning, but it really was incredibly insensitive."
She said it was no way to go about getting a politician to listen to what you have to say.
"I've got emails which have accused me of being ignorant on the subject, or incompetent. But I thought the email trying to link my personal experience of miscarriages to water fluoridation was really a new low."
She is "100 percent certain" fluoride in the water supply is not behind the miscarriages.
"As a politician we get a lot of correspondence, some of which can be quite negative, hurtful or personally confronting. I've found a great way of dealing with that is actually to just put it out there and share it with people."