Smoking and pregnancy should not mix. Unfortunately, at least 10 percent of women smoke while pregnant, according to a 2006 study published in “National Vital Statistics Reports.” A baby exposed to smoke in utero is at risk for many different problems. The more a woman smokes, the higher the risk. Women who stop smoking by the middle of the pregnancy can greatly reduce their risk for these adverse outcomes.
Miscarriage and Stillbirth
Smoking during pregnancy is a major preventable cause of miscarriage, or death of the fetus before about 20 weeks gestation, and stillbirth, or fetal death after 20 weeks. Cigarette smoke contains over 4000 chemicals and toxins, including carbon monoxide and formaldehyde, which pass directly to the fetus through the mother’s bloodstream. These chemicals can overwhelm the developing systems of a baby, leading to the baby’s demise.
Growth Restriction
Smoking constricts the blood vessels leading to the placenta, reducing blood flow. The baby receives its oxygen and nutrients from the placenta, so less blood flow means less nutrients for the baby. The result can be growth restriction, which is when the baby’s body parts as measured by ultrasound lag behind those expected for that gestational age. Growth-restricted babies are generally born underweight. Small, underweight babies face increased risks for various health problems, including infections, breathing problems and difficulty feeding and gaining weight.
Premature Rupture of Membranes
Smoking increases the chance for premature rupture of membranes (PROM), or breaking of the bag of water that holds the baby before labor begins. PROM is associated with several complications, including a dangerous infection of the placental membranes called chorioamnionitis, placental abruption (premature separation of the placenta from the uterine wall) and premature birth. These complications jeopardize the life of the baby and mother. Babies born premature are at risk for the same problems as babies born underweight and additionally can develop long term problems such as learning disabilities and behavior issues.
Birth Defects
Although results vary regarding whether smoking during pregnancy can cause birth defects, some studies have found an increased risk for defects, including limb reduction defects (incomplete development of an arm or leg), heart defects, and cleft lip with or without cleft palate. A study published in the journal “Epidemiology” in 2010 even found that passive maternal smoking, or exposure to second-hand smoke, increased the risk for cleft lip with or without cleft palate in the baby. Because birth defects generally occur during the first trimester, when the fetal organs are forming, the beginning of the pregnancy is the riskiest time to smoke.
About this Author
Based in Los Angeles, Roxanne Maas holds a master’s degree in genetic counseling with more than 12 years of experience communicating complex genetics and pregnancy information. She has published several abstracts in scientific journals, presented posters at national genetics meetings, and published health-related articles on LIVESTRONG.com.
