A BBC Wales investigation has found that women desperate to become parents are being harassed for sex and offered cheap, illegal sperm samples online.

Swipe Right for Sperm, a new BBC Cymru Wales programme airing on BBC One Wales on Monday, June 8 and BBC Two on Thursday, June 18, has discovered that individuals who are unable to access fertility treatment are seeking out options on social media, which is driving a growing unregulated market – with some even turning to "Tinder for sperm" websites.

As part of the investigation, the team paid £100 for a next-day delivery sample from a man who advertised his "baby batter" online and sent it chilled by a frozen carton of tomato passata. The same online advert states that people can "rely" on a man called Joe Donor for a delivery in the post. He's a prolific donor who claims to have 180 children around the world conceived through sex and artificial insemination.

The Human Fertilisation and Embryology Authority (HFEA) defined unregulated donation as a donation occurring outside of an HFEA-licensed premises, adding it was a criminal offence in the UK.

Joe Donor disputed the HFEA’s view and said he understood giving private donations, including charging for them, is legal.

One couple, Tianna and her wife Nikki from South Wales, turned to unregulated donation after they discovered they were not eligible for NHS funding, and felt private treatment was too expensive.

Speaking about this, Tianna said: "I always knew I wanted to be a mum, we knew that there was something missing from our family."

She added she was aware of the risks and wary of any pressure from potential donors.

"You do get weirdos who are in it for the complete wrong reasons. There's a website, it's kind of like a mixture between a catalogue and Tinder, you can filter eye colour, hair colour, so you can look for exactly what it is you're looking for."

The couple were looking for artificial insemination but said men often recommended sex as the best option.

Tianna continued: "I think it was really helpful that me and my wife had each other so there was no way that anyone could really pressure us into doing something we didn't want to do, because when all you want to have is a baby you're in a really vulnerable position."

Tianna and Nikki finally found a donor they felt safe with on a co-parenting website and created a contract so that all parties were aware of their plans for contact and parental rights. But this is not a legal contract.

Tianna said: “There is still a chance that in the future, he could come and try and start claiming parental rights and take us through a court case.”

Clare Ettinghausen from the HFEA said: “Some of these donors are advertising as natural insemination only, which is essentially in some cases coercing women to have sex when they possibly wouldn't want to.”

Presented by Gemma Dunstan, BBC Wales Investigates: Swipe Right for Sperm, airs tonight (June 8) at 8:30pm on BBC One Wales and on June 18 at 10pm on BBC Two.