We have come to the house of a woman we won't name, in a state we won't name, to talk to her about her desperate wish to have a daughter.

We have agreed to call this woman "Kate", and such is her fear of social backlash that when we interview her, we film her in silhouette.

Several other women had agreed to be interviewed by Lateline, then changed their minds over concerns they would be targeted on social media for their views.

Kate suffers from what is known as gender disappointment.

How seriously you take that concept probably goes a long way to determining how you feel about whether Australia should legalise gender selection — the use of IVF to get the baby of your desired sex.

How does sex selection work? A couple goes through an IVF cycle and the embryos are tested to determine gender.

A couple goes through an IVF cycle and the embryos are tested to determine gender. The mother is then implanted with embryos of a desired gender.

The mother is then implanted with embryos of a desired gender. Gender selection is only allowed in Australia if there is a genetic disorder associated with one gender.

Gender selection is only allowed in Australia if there is a genetic disorder associated with one gender. Gender selection is available in many other countries including the US and Thailand.

Gender selection is available in many other countries including the US and Thailand. Each year more than 100 Australian couples travel overseas for gender selection.

Each year more than 100 Australian couples travel overseas for gender selection. IVF gender selection overseas can cost tens of thousands of dollars.

Gender disappointment is not a medically recognised condition. Critics call it a social construct, but venture into some closed online chat forums and you will find hundreds of Australian women who are sharing their disappointment over the sex of their children.

Kate, 29, already has two boys and is five months pregnant with her third boy — a revelation that left her "gutted".

"I went to the bedroom and cried for a really long time," she says.

"Then my husband came in and he cried as well.

"You feel horrible, because you want to be excited that it's a boy, but part of you was really disappointed."

Kate is desperate for a daughter but she insists she doesn't want a "a ballerina, Barbie girl".

"I'm not wanting someone that I can dress in pink and tie her hair up. I'm not wanting any of that," she says.

"It's just that I always imagined her and she's always existed. I feel the family isn't complete without her."

Kate says her family won't feel complete until she has a daughter. ( ABC: Brant Cumming )

Kate and others who feel gender disappointment describe it as a guilt-ridden, debilitating depression.

"Unless someone has that desire themselves and feels how it can be all-consuming, they can't understand what it's like," she says.

"It'd be so easy if I could just switch it off and just be happy."

Gender selection is not allowed in Australia, but an ethics committee of the National Health and Medical Research Council has been reviewing the guidelines for assisted reproductive technology and may make a recommendation for change.

"To you she doesn't exist yet, but to us we can't imagine a life without her," Kate wrote in her submission to the committee.

"It's really a personal decision and it's not going to hurt people the way that people seem to think it is.

"It's not going to affect the gender ratio, and it's not going to place these unrealistic ideas on the children that are being born."

Swaying with sex positions, Chinese medicine

With gender selection unavailable to couples in Australia, many hoping for a certain sex try to sway the gender of the child by using specific sexual positions and timing intercourse.

The science of so-called gender "swaying" has never been proven, but many still try it.

"We did diets, supplements, timing, the Chinese calendar, the moon phase, extra exercises, everything we could have thought of, everything we could find online," Kate says.

There is even an elderly woman in Melbourne who claims to have a 100 per cent success rate in gender swaying using Chinese medicine.

Couples are only able to contact the woman via text message and then they are told they need to commit to up to eight face-to-face fortnightly consultations, as well as a strict diet, to get their wish.

Kate cannot afford to go overseas where IVF gender selection is legal, so she is holding out for a reversal in policy here.

Going to extreme measures

For Townsville mother-of-four Sarah Williams, it was the price she had to pay to get the family balance she wanted.

Sarah has two boys, aged nine and seven, and four-year-old twin girls.

"I will talk to people and they go, 'Oh you're so lucky you got the two boys and then you got the two girls', and I will go, 'No, luck had nothing to do with that. I had to do some extreme measures to get my girls'," she says.

Sarah Williams travelled to the US so she could select the gender of her youngest children. ( ABC: Brant Cumming )

After having two boys, Sarah went to California, where gender selection is allowed, to go through an IVF cycle and be implanted only with the female embryos it produced.

Sarah had gone through the same range of emotions Kate is now experiencing.

"It's gut-wrenching. I would be in tears," she says.

"It never crossed my mind that I wouldn't have a daughter, and I wanted that because I was so close to my mum that I wanted to be the mum that was that close to my daughter," she says.

She rejects suggestions sex selection is akin to creating a designer baby.

"I didn't choose any eye colour, I didn't choose a hair colour, I just chose a girl over a boy," she says.

Several years ago Sarah would not have spoken out about gender selection.

These days she is more relaxed.

"We're very glad we did it, and we don't have any regrets no matter what anyone says," she says.

She is adamant that her daughters will not be expected to conform to gender stereotypes.

"I'm not going to force anything on my children," she says.

"They can be gay, they can be bi, they can do whatever they want with their lives.

"I'm a live-and-let-live kind of person.

"I don't judge other people, and I just hope they don't judge me in the same way."