Pregnant Smoking Tied To Five-Fold SIDS Increase, Rutgers Study Finds

NEW BRUNSWICK, NJ — We're always told that smoking while pregnant — and not pregnant — is bad for you, and can harm the developing fetus.

Now, researchers at Rutgers University found out exactly why smoking while pregnant is so harmful: There is an extremely strong link between mothers who smoked while pregnant and their baby later experiencing a sudden unexpected infant death (SUID), which includes Sudden Unfant Death Syndrome (SIDS).

The study's lead authors are Barbara Ostfeld and Thomas Hegyi, both Rutgers pediatric professors at Robert Wood Johnson Medical School. They examined data from nearly 5 million births and SUID deaths recorded by the CDC for the years 2012 and 2013.

They found that the longer the duration of smoking, the higher the risk of a newborn suddenly dying before the baby reaches one year of age.

You can read their study here; it was published in the Journal of Perinatology. Scientists have previously found that babies born to mothers who smoked reported a lower birthweight and a smaller head circumference.

"Previous studies have established that smoking during pregnancy is associated with changes in parts of the developing brain that result in an infant being more vulnerable to a drop in oxygen," explained Ostfeld.

Their analysis found that infants born to African-American and white mothers in the United States exposed to maternal smoking throughout pregnancy were more than five times as likely as infants of never-smokers to suffer a sudden unexpected infant death. Because racial disparity has frequently been found in SUID risk factors, this Rutgers study is unique because it found a high correlation of smoking and SUID deaths — no matter the race of the mother.

The highest risk levels of a baby dying in the first year of its life were found when smoking continued throughout pregnancy. The risk of SUID rose with every trimester of in-utero exposure to the smoke, the researchers found.

"The message is simple," said lead author Dr. Ostfeld, director of the SIDS Center of New Jersey. "Smoking greatly elevates the risk of sudden unexpected infant death."

For non-Hispanic Black women who never smoked, Ostfeld's team found a SUID rate of 1.07 deaths per 1,000 live births. However, the SUID death rate rose to 3.80 for infants born to mothers who smoked throughout pregnancy.

The researchers found there were about 10 percent of Black women who smoked either during or before pregnancy; their babies did not experience a sudden unexpected infant death.

But for babies who did die suddenly and unexpectedly, which included deaths classified as SIDS, they found that nearly 25 percent of their mothers had smoked either during or before pregnancy.

That was the data of non-Hispanic Black mothers. The numbers became even more dramatic for non-Hispanic white mothers:

About 16 percent of white women surveyed smoked either during or before pregnancy, and their babies did not die. However, among babies who did die suddenly and unexpectedly, fully half of the white mothers had smoked either during or before pregnancy.

There is a "strong connection between smoking and SUID," said Dr. Hegyi, medical director of the SIDS Center of New Jersey. The researchers also found that for those mothers who ever smoked, the most common pattern for both racial groups was to continue smoking throughout pregnancy. In cases of SUID, fully 78 percent of white mothers and 66 percent of Black mothers who were classified as ever being smokers reported doing so in all trimesters.

Dr. Hegyi said their research:

"Underscores the difficulty smokers have with quitting and suggests a national need for more effective approaches, as well as better access to services" to help pregnant mothers quit smoking.

The research team gathered data on infants born between 24 and 42 weeks of gestation, from anonymous United States birth and death records maintained by the Centers for Disease Control for the period of 2012-2013.

These criteria resulted in the inclusion of 3.3 million births to white women and 857,864 to Black women. SUID describes the sudden unexpected death of an infant at less than 365 days of age.