Smoking and Pregnancy:
In the United States more than 20 percent of women smoke. According to the World Health Organization, a similar number of women in other developed countries smoke, and about 9 percent of women in developing countries smoke. Many of these women smoke while they are pregnant. This is a major public health problem because, not only can smoking harm a woman’s health, but smoking during pregnancy can lead to pregnancy complications and serious health problems in newborns.
Statistics from the United States are compelling. If all pregnant women in the United States stopped smoking, there would be an estimated 11 percent reduction in stillbirths and a 5 percent reduction in newborn deaths, according to the U.S. Public Health Service. Currently, at least 11 percent of women in the United States smoke during pregnancy.
Cigarette smoke contains more than 2,500 chemicals. It is not known for certain which of these chemicals are harmful to a developing baby. However, both nicotine and carbon monoxide are believed to play a role in causing adverse pregnancy outcomes.
How can smoking harm the newborn?
Smoking nearly doubles a woman's risk of having a low-birthweight baby. In 2002, 12.2 percent of babies born to smokers in the United States were of low birthweight (less than 5½ pounds), compared to 7.5 percent of babies of nonsmokers. Low birthweight can result from poor growth before birth, preterm delivery or a combination of both. Smoking has long been known to slow fetal growth. Studies also suggest that smoking increases the risk of preterm delivery 37 weeks of gestation). Premature and low-birthweight babies face an increased risk of serious health problems during the newborn period, chronic lifelong disabilities (such as cerebral palsy, mental retardation and learning problems) and even death.
The more a pregnant woman smokes, the greater the risk to her baby. However, if a woman stops smoking by the end of her first trimester of pregnancy, she is no more likely to have a low-birthweight baby than a woman who never smoked. Even if a woman has not been able to stop smoking in her first or second trimester, stopping during the third trimester can still improve her baby’s growth.
Can smoking cause pregnancy complications?
Smoking has been associated with a number of pregnancy complications. Smoking cigarettes appears to double a woman’s risk of developing placental problems. These include placenta previa (low-lying placenta that covers part or all of the opening of the uterus) and placental abruption (in which the placenta peels away, partially or almost completely, from the uterine wall before delivery). Both can result in heavy bleeding during delivery that can endanger mother and baby, although a cesarean delivery can prevent most deaths. Placental problems contribute to the slightly increased risk of stillbirth that is associated with smoking.
Smoking in pregnancy also appears to increase a woman’s risk of premature rupture of the membranes (PROM) (when the sac inside the uterus that holds the baby breaks before labor begins). A woman with PROM may experience a trickle or gush of fluid from her vagina when her water breaks. Usually, she will go into labor within a few hours. When PROM occurs before 37 weeks of pregnancy it is called preterm PROM, and it often results in the birth of a premature baby.