Sadie Cox, 40, led 10 bridesmaids and a flower girl at a big white wedding for Deri, 27, and Ben Rogers-Wood, 30.
She has four kids herself and wanted to help longtime pals Deri and Ben have their first child together.
The baby was conceived using Ben’s sperm and a donor egg in a £7,000 procedure at a private clinic.
Pub manager Deri said: “I have known Sadie for more than a decade and we trust her and love her like family.
“It was even Sadie that introduced me and Ben back in 2013. She had always offered to be our surrogate and it was just a matter of waiting for the right time.
“We all agreed the baby would be conceived using a donor egg and Ben’s sperm. Luckily Sadie fell pregnant with our baby straight away.”
The process to prepare Sadie’s body for the pregnancy took a year. She had to boost her oestrogen levels with tablets and had nightly hormone injections before the embryo was implanted in January.
Sadie, of Cwmbran, near Newport, South Wales, said: “I knew it had worked immediately because I was paying attention to my body and looking for all the usual pregnancy symptoms.
“I have had good days and bad days with nausea and feeling tired but on the whole I feel great.”
When Sadie was six weeks pregnant Deri and Ben were able to see their baby’s heartbeat on a screen during a scan at a private clinic.
Deri said: “We are still being treated privately until the baby is 12 weeks. After that we transfer to NHS scans and Sadie will get assigned a midwife and will give birth at our local hospital.
“We will go for another private scan to find out the sex a bit earlier than usual though, because we are so excited.”
Sadie has been keeping a journal to one day give to the child so he or she can learn about how they were conceived.
She said: “I have no doubts about my role in this and that is purely to carry this baby in the short term to give to Deri and Ben, who will be the best parents.
“I’m very much in the right frame of mind and can’t wait to be in the baby’s life as a friend of the family.
“One day the baby will know about the special favour I did for both dads and that makes me really proud.
“I was adopted myself and so I know all about the incredible love that can be received from a couple that aren’t your birth parents.
“Being loved is the most important thing for any child.”
Ben and Deri chose 10 pals plus Sadie as bridesmaids to make their big day a truly white wedding – inviting each of them to wear their favourite dress.
Deri – who already has son Maccaulay, nine from a previous relationship – said: “I figured every wedding needs a wedding dress – so why not 10?”
Both men will be with Sadie when she gives birth in September.
But Sadie teased: “Ben and Deri will be amazing fathers to this baby but I don’t know how much use they will be in the labour.
“They are both very squeamish and I can see them fainting on the floor!
“I might ask a female friend to come along and support me. But we’ll cross that bridge when it comes. Now it’s just a waiting game.”