On what grounds can indefinite leave to remain after a 2 year spouse visa be refused?

hello, my husband is due to apply for indefinite leave to remain after having a 2 year spouse visa. He is a self employed builder and has not worked for the whole of the 2 years, there are some months where he was not working. Would this be a problem vis-a-vis his application? I worked for 11 months of his visa time but was then at home after I had a baby. If there is anyone trained in immigration law please advise me.