On today's TV news (UK) there has been an item about how some women who have had cesaerians find it difficult to get pregnant again. It may take up to a year of trying. The researchers say they don't know why this happens. Sounds to me like it may be because of adhesions but if the researchers don't know...
I don't have details but the item may be on the BBC website (www.BBC.co.uk, I think).