Smoking and consuming oral contraceptive pills increase the risk of developing deep vein thrombosis (DVT). This is especially so if you are obese, above the age of 35 years old and are a heavy smoker. If all these 3 categories apply to you then oral contraceptives or, for that matter, any hormonal medication is contraindicated.
If you have 1 or 2 of these risk factors then hormonal medication is relatively contraindicated and you need to discuss the risks versus the benefits with a gynaecologist to determine if it is still safe for you to be on the birth control pill or will other alternatives be a safer option.
With this in mind, smoking is not good for your general health in the first place, so I would strongly recommend that you quit smoking regardless of whether you are going to be on the oral contraceptive pill or not.
