I am 414 weeks pregnant, I smoked over half of my life I've been almost a month with nothing but an e-cig to curb nicotine cravings. My baby is fine so far. It's not healthy to smoke when you're pregnant but if you are already pregnant it's not healthy to quit cold turkey, as the stress can cause you to miscarry. Cut way down til you can ween yourself off. Even my dr. told me the e-cig is safer for my baby
Smoking can cause you to miscarry, still birth, low birth weight, preterm. And those are just the worst things. Low birth weight and preterm cause a whole new set of issues. It's best to quit before you get pregnant. You can also google it and see a full list of possible issues.
Good luck!