Asked to recall their pre-birth expectations, the study found 44% of women did not feel anyone had honestly prepared them for giving birth.
But despite this, 47% said they actually enjoyed the experience, the survey of over 1,662 Mumsnet users found.
Meanwhile, 44% would do it differently the next time or not give birth again, and 64% said it was the most physically painful experience of their lives.
A spokeswoman for the website explained the apparent inconsistent figures of 47% saying they enjoyed it and 64% agreeing about the extent of the pain as "just one of those contradictions of birth".
The survey found 19% of women were still having sex in their ninth month.
The majority of women - 81% - said images and portrayals of women giving birth in TV and films are normally unrealistic.
Justine Roberts, Mumsnet Founder, said: "It can be tricky to find unvarnished truth about what giving birth is actually like.
"We're either presented with a soft-focus vision of loveliness with the mum-to-be barely breaking out in sweat, or we're scared half to death with tales of surgery, emergency and ruthless pain."