At the end of her 5am-6am early edition show today, Smalley issued an on-air apology, her voice breaking as she expressed her regret over the comments.
"I made a flippant comment yesterday which upset and hurt a lot of people. It went on-air in an environment where it was out of context and was hurtful.
"It was stupid, it was judgmental and offensive. It was not made as a statement of fact and it was in no way representative of any opinion I have ever held, ever and I'm sorry, I truly am.
"My role as a journalist has always been to inform and not to offend and yesterday I crossed that line. I'm so very sorry that I said what I did and I'm very sorry for the hurt that I caused and the many people that I let down, not least myself, my friends and my family."
Smalley made the comments yesterday after discussing a story in the New Zealand Herald which revealed a morning-after pill was ineffective for women weighing over 70kg.
The average weight of a woman in New Zealand is 72kg.
The comments were made during an ad break when her microphone was mistakenly left on.
