There is an even more sure fire method to avoid pregnancy, but then, I guess maybe your husband doesn't like celibacy. Seriously, non one can expect heroc virtue from anyone except themselves.
Not having sex is still another way to avoid having children. If supposedly using birth control is keeping God from fertilizing us then avoiding the whole marriage 'rights'is not only keeping God from giving us with children it is also denying our partner a sexual relationship...we're not suppose to do that.