Let's talk about why we want pregnant moms to stop smoking. A mom who smokes, has less circulating oxygen in her body and therefore, less oxygen is available for her growing baby. This is called fetal hypoxia. Additionally, nicotine goes right across the placenta and into the bloodstream of your fetus.
So, how do all of these things affect your baby? Well, all of this can lead to an increased risk of: fetal growth restriction (having a small fetus that doesn't grow properly), placenta previa (a placenta that implants over the cervix instead of on the uterine wall), placental abruption (a placenta that pulls off the wall of the uterus prematurely), premature rupture of membranes (breaking your water bag early), preterm delivery, low birth weight baby (less than 5 lbs), stillborn, newborn death, SIDS (sudden infant death syndrome), and childhood asthma, colic and obesity. I know, this sounds awful.
So, the bottom line is that there has never been a better time to quit smoking. If you need help, ask your practitioner for suggestions. There are many options available, even for pregnant women.