The risks involved with smoking during pregnancy

Fewer women are smoking during their pregnancy now than in the past. But many women still smoke. Even if a pregnant woman doesn't smoke, she may be exposed to secondhand smoke at home, at work, or in social settings. New research has focused on the dangers from third-hand smoke. These are the chemicals, particles, and gases of tobacco that are left on hair, clothing, and furnishings.

Smoke can be harmful to a fetus in many ways. It may cause:

• Low birth weight

• Preterm birth

• Stillbirths

• Higher risk for birth defects

Babies born to smokers may also have these problems:

• Poor lung development

• Asthma and respiratory infections

• Higher risk for sudden infant death syndrome (SIDS)

• Physical growth problems

• Intellectual development problems

• Behavioral problems

• Childhood obesity

• Colic

The mother can also have problems during her pregnancy because of smoking:

• Placental problems

• Preterm labor

• Infections in the uterus

Researchers think that carbon monoxide and nicotine from cigarettes cause many of these harmful effects. Carbon monoxide lowers oxygen in the blood. Nicotine stimulates certain hormones.

Babies of mothers who are regularly exposed to secondhand smoke during pregnancy are more likely to have reduced fetal growth and low birth weight.

A woman who quits smoking early in her pregnancy raises her chance of delivering a healthy baby.