My daughter was 16 when she became pregnant, unintentionally. People really used to look at her and you could almost hear their judgemental remarks; the middle class mummies gave the most scathing looks. Thankfully nobody actually ever said anything.
Four years down the line she has a gorgeous, amazing little 4 year old boy who is mixed race so now people still look at her and no doubt some of them judge.
It's best to try and let it wash over you if possible. If they wasn't judging her for being a young mum then it would be for some other reason ie her clothes, her teeth, her bum.....we can be a judgemental lot at times.
I do think there is a Daily Mail sort of culture at times in society ie she is a young mum therefore she Must be a single mum, a benefit scrounger, she only did it to get a council house, the kid wil be delinquent.....believe me the list goes on and on.
My own feelings regarding my daughter's pregnancy at such a young age was one of some sadness and regret and a feeling that I had been a bad mother somehow. The reality however is that she had sex with a boy which is perfectly natural and normal and it resulted in pregnancy.
Hold your head high. Be proud of your lovely daughter and your fantastic, beautiful grandson. He will bring you unimaginable joy and pride so stuff what anyone else thinks or says. Perhaps they are just a bit jealous in reality. You don't need to say anything.....just glow with love and pride.