AAARGH.
No it will not have any effect on M/F ratios.
You can encourage higher % of females with proper lighting, soil conditions, and temps, but the difference will be so small that you'd need a very large sample size for the numbers to even be statistically significant.
If estrogen worked, don't you think there would already be a product on the market? There ARE female encouraging products such as SensaSoak, which is a small bottle of horseshit sold for $25 US. It works... to encourage hermaphrodites. Quite well, actually.
You want females, make feminized seeds.

EDIT: And if I were your girlfriend/sister/whoever you're pinching pills off of, if I found out, you would live to rue the day you ever came up with this harebrained scheme. Of course, if she's on a pill that has a rest period, ask her to give you a couple of the 'place holder' sugar pills you take when you're actually having your period. They'll actually be GOOD for your plant. Plants like sugar. But the sugar by the coffee maker will work just as well.
stinkyattic Reviewed by stinkyattic on . birth control as a nute i heard that if you mix 1 birth control pill in a gallon of water for watering it makes the marijuana plant mature faster believe it or not it has been proven on tomato weed plants and many have claimed it works on marijuana is this true or is it just a stupid idea please express your knowledge of this matter Rating: 5