The website is calling for a more honest approach to family life and an end to the guilty subterfuge of mothers who feel unable to achieve an idealised view of parenthood.
Siobhan Freegard, a co-founder of the site, said: "Mums need to be more honest with each other" as trying to be perfect made them feel, instead, "inadequate".
She cited the example of a mother who was exhausted and went back to bed during the day, explaining her failure to answer the phone as being because her hands had been covered in flour while making biscuits.
The sense of inadequacy was caused by peer pressure from other mothers at the school gate or the nursery, the survey found, with more than nine out of 10 comparing themselves to other mothers.
The website is launching what it calls "The Real Parenting Revolution", which encourages parents to accept the reality of how they live, rather than feeling bad about not living up to a myth of perfection.
"It's the imperfections that make us human," Ms Freegard said.
If you'd like to comment on this story, please email the editorial team at: firstname.lastname@example.org