Every cigarette you smoke increases the risks to your pregnancy. A smoker's body is sensitive to the first doses of nicotine each day, and even just one or two cigarettes will significantly tighten your blood vessels. That's why even a light habit can have a bad effect on your baby's health.
Smoking during pregnancy exposes a baby to carbon monoxide, which limits the baby's supply of oxygen and nutrients. Exposure to nicotine also increases a baby's heart rate and reduces fetal breathing movements.
Breathing secondhand smoke during pregnancy can also affect your baby's health. Women who don't smoke but are exposed to secondhand smoke are at increased risk of pregnancy loss or having a baby who has birth defects or a low birth weight.
Here are the ways smoking affects your baby:
- Babies whose mother smoked in the first trimester of pregnancy are more likely to have a heart defect at birth. The defects included those that obstruct the flow of blood from the right side of the heart into the lungs and openings between the upper chambers of the heart.
- On average, a pack-a-day habit during pregnancy will shave about a half-pound from a baby's birth weight. Smoking two packs a day throughout your pregnancy could make your baby a full pound or more lighter.
- Undersize babies tend to have underdeveloped bodies. Their lungs may not be ready to work on their own, which means they may spend their first days or weeks attached to a respirator. After they're breathing on their own these babies may have continuing breathing problems because of delayed lung development or other adverse effects of nicotine. Children whose mothers smoked during pregnancy are especially vulnerable to asthma and have double the risk of sudden infant death syndrome (SIDS).
- Smoking during pregnancy can have lifelong effects on your baby's brain. Children of pregnant smokers are especially likely to have learning disorders, behavioral problems, and relatively low IQs.
Smoking during pregnancy has been linked with other problems as well, including:
- Vaginal bleeding
- Low birth weight
- Preterm premature rupture of the membranes
- Preterm labor
- Premature birth
- Birth defects involving the heart, limbs, skull, muscles and other areas
- Pregnancy loss
Smoking during pregnancy can also affect a baby after he or she is born, increasing the risk of:
- Sudden infant death syndrome (SIDS)
- Respiratory infections
- Childhood obesity
Some research also suggests that smoking during pregnancy might affect a child's emotional development, behavior and ability to learn. Smoking during pregnancy might even impair a child's own fertility.