Many young Kiwi women are being sexually promiscuous because they feel a need to compete with men.

That's the view of sex therapist Mary Hodson who is seeing "heaps of hurt young women" who have had numerous partners - many of whom they don't even know very well.

"There's kind [of] a strata in the world of women today and I think there are some very young girls engaging in a lot of sexual activity. It's almost as if they have got to compete with the boys and be the same as boys."

Mrs Hodson, co-owner and director of Sex Therapy NZ, said there was also a slightly older group of single women, in their late 20s and 30s, who were feeling like they "have to compete to get a man ... they have got to be sexual to engage that person in a relationship."

The result was both groups of women having sex very soon after meeting a partner - often on the same night as meeting someone in a pub - rather than taking the time to get to know them and form a relationship first.

"The danger of that is you are engaging with somebody before you know if they are emotionally safe for you" or even sexually safe.

Often women in the older group then feel hurt when the one-night stand doesn't turn into something more serious.

Mrs Hodson's comments follow calls from gynaecologist Dr Albert Makary who last week asked national leaders, sports stars, schools and the media to start a national campaign against promiscuity.

Dr Makary, who is based in Timaru, told a Forum on the Family in Auckland on Friday that Kiwi society normalised drunkenness and promiscuity and young women were now wearing their sexual popularity as a badge of honour.

He said the problem had now become so bad there were "thousands and thousands" of cases each year of women not being able to remember who they slept with the previous day.

A survey by a condom maker Durex found New Zealand women were the most promiscuous in the world, having on average 20.3 sexual partners. The world average was 7.3 while Kiwi men had 16.8.

Mrs Hodson said "sexual freedom" was part of the problem in New Zealand.

She said times have changed so much that the fear of getting pregnant or catching a sexually transmitted disease were no longer seen as reasons for not having sex.

"We don't even call them sexually transmitted diseases anymore, we've changed that to infections which kind of downgrades it and makes it not as serious as they can be."

"It's the attitude that we don't have to worry about them anymore."

Drinking too much was another reason why some women, especially very young women, were sleeping with so many people.

"We need a campaign about women keeping themselves safe," she said.