Hi beth. well i have had experience of smoking in prregnancy, as i smoked during 3 pregnancies. im 26! well my 1st preg. i misscarried at 10 wks. my 2nd i went for my scan and was told my baby had died at 7 wks, and i had to have everything removed! then i fell again, i stopped straight away, as i knew the dangers then. A wk later my father in law died. so i smoked for about a week, so i would have been about 7-8 wk preg. then i stopped and sailed through my prgnancy. My beautiful baby was born 8lb!!! im only tiny myself. My friend however who couldnt give up in her preg. her waters broke at 29 wks, she spent 3 wks in hosp and went into prem labor at 32 wks, babt was born weighing 3lb, and was very poorly! My daughter was perfect. But at 4 yrs old she developed asthma. I will never know now if it was my fault she got asthma, and its horrible to think it could have been my fault!! The baby is fully developed by 12 wks.. it just grows from then onwards, the 1st 12 wks are the crucial time when all the organs and systems are begining. Smoking in pregnancy is the cause of 120,000 miscarriages every year!!!! Along with the hundreds of babys that die of cot death too. If i had my time with her again, i would have given up before i even started trying to get preg. As i said, im 26, im not giving u a telling off or a guilt trip.. but i have been there, and having a baby, being a mum is all about sacrifice. i would give my life for my child!!!! giving up smoking is a small sacrifice to make to give your baby the very best chance in life!!!! I did a study on smoking in preg when i was in college, and its really really scary stuff... what it does to your baby. Its really not worth it. All i did whenever i wanted a fag when i was preg, was pick up my scan photo and thought about my baby... remember.... sacrifice!!!! Good luck beth. it really is the best thing for your baby xx