I'm 20 years old and have been sexually active for about 4 years now. I wasn't in a long term relationship until 10 months ago, and it's got to the stage now where I need to go on the pill as condoms are just really inconvenient (I'm not overly keen on the pill that's why I've put it off for 10 months but I know I need to because my boyfriend and I are becoming a bit to lax about things...)
Basically, I've always been slim, and always been underweight for my height. I'm about 1 1/2 to 2 stone below what I should be. What I was wondering, and sorry if it's too much of a medical question, but does being underweight affect the effectiveness of the pill? I'm sure I read somewhere once that it decreases its 'safety' on people who are significantly underweight or overweight. On the flip side, a common side effect of the pill is weight gain, so assuming it's still effective for an underweight girl to go on the pill, it could actually improve my weight right?!