In 2012, for every $100 you earn, you will need to contribute $1.83 in EI premiums up to a defined maximum—the same amount that employees pay. This means the most you will pay in EI premiums for 2012 is $839.97.
So for math examples .... if your taxable income is around the $12,000 - $15,000 mark after your expenses you would be getting only $6600 ~ $8200 in mat leave benefits for the course of a year which sounds awesome for sure.... however my understanding is that once you opt IN to this EI plan for self employed people you cannot opt OUT so if you are planning on being self employed for the next 10-30 years you will wind up paying at LEAST 8399.70 in premiums so way more than you get 'out' of the program and well up to a total of $25,119 in premiums for that measly $6600 you got way back when and that is assuming RATES do not go up on you over the course of the years which you know they will cause they have consistently been going up!

Seriously IMO if I were planning on having a baby I would put 1 child's FEES away a week for the nine months of my maternity leave and FUND my own maternity leave ... and than you can put your $900 a year away for the next 10 - 30 years of your working life and fund your RETIREMENT plan earning compound interest and so forth on that savings!