I suspect it's more the husbands not wanting children anyway by their own personal nature, but they hide behind that to come off as very "spiritual" and sacrificing, till after Armageddon. Though some wives are that way also, many of the wives are put off to wait also.
Too, if they are already in full-time work of special pioneers, Bethelites, missionaries, CO, or DO, they would have to leave and get a real job to support their family.
Unfortunately, many would see "parenthood" as a demotion in their 'position' of their world/life.