I think there's no question that, to increase the number of years you could use for an earnings, dropout would help, because it would increase the CPP benefits that women get in retirement.
Is this the best way of doing it? I think it depends to some degree what kind of family unit you have and what the reasons for unpaid labour are. We're working on the assumption here that unpaid labour is not done by choice. It's done for reasons of child care. I'm going to work with that assumption. I'm also going to work with the assumption that there's a two-income family. Another approach would be to allow for greater income splitting within couple units when you have children being raised.
The reason I suggest this is that for couples or for women it's very difficult to raise children, because they're a heavy cost to the family, and yet they have a very significant benefit to society, because they keep society from aging or they slow the process of aging. That's one of the great challenges that Canada is facing: the replacement ratio isn't as high as it needs to be and we don't have enough workers coming up to replace the ones who are going out. One of the reasons for this is that it's very difficult for families to have children. I think it would make sense for society to recognize that, by perhaps allowing more income splitting within couples to lower their tax rates, to allow them to make more effective use of their income. This will probably make it easier for them to save for retirement while they're working.