Zoe's Law protesters target NSW Parliament

Hundreds of women will protest Zoe's Law outside NSW Parliament on Thursday morning.

Opponents of the controversial bill say the law could restrict the ability of women to abort a fetus and could lead to doctors facing criminal offences.

Under proposed changes before parliament, someone could be charged with harming a fetus that is either 20 weeks or 400 grams by allowing it to be treated as a living person.

Women's Electoral Lobby chair Melanie Fernandez says women's reproductive rights are at risk.

"There should absolutely be consequences for any harm done to a fetus," she said.

"But we should never have a situation where the human rights of a fetus come into conflict with a woman's human rights."

However, victims of crime advocate Howard Brown says Zoe's Law means perpetrators of crimes such as assaults, homicides and car accidents will be punished for taking the life of a viable fetus.

"It happens far too often. The law needs to recognise it," he said.

Premier Mike Baird personally supports the plan but has vowed to hold a conscience vote on the topic, reducing the chances of the legislation passing.