Daily smokeless nicotine tied to earlier delivery vs. cigarette use during pregnancy

Key takeaways:

• Women who used daily snuff during the third trimester had reduced gestational length vs. women who smoked cigarettes.
• Daily snuff use while pregnant did not affect fetal growth.

Daily snuff use throughout the third trimester of pregnancy was associated with reduced median gestational length by more days compared with daily cigarette use, according to findings published in BMC Pregnancy and Childbirth.

Snuff is a smokeless source of nicotine common in Scandinavia that is more frequently being used by women of reproductive age, according to Rolv T. Lie, MD, professor of medical statistics in the department of global public health and primary care at the University of Bergen and the Centre for Fertility and Health at the Norwegian Institute of Public Health in Norway.

“The Medical Birth Registry of Norway recently started collection of snuff exposure before and during pregnancy. These Norwegian data have the advantage of distinguishing between daily and occasional snuff use,” Lie and colleagues wrote. “Data on snuff will be available for all births in Norway once data collection systems are updated in all regions. As of today, data are available from two health regions in the western and central parts of Norway.”

Lie and colleagues conducted a register-based study using data from the Medical Birth Registry of Norway on snuff use during 18,042 pregnancies delivered in 2020 and 2021 in west and central regions of Norway. Researchers estimated associations between snuff use and gestational length and birth weight at term and compared associations with pregnancy outcomes based on maternal snuff and cigarette use.

Overall, 12.4% of nonsmoking women reported daily and 4.3% reported occasional snuff use before pregnancy. A total of 4.6% of women reported continuing snuff use during pregnancy, of whom 1.2% reported daily and 3% reported occasional use during the third trimester.

Women who reported daily vs. no snuff use during the third trimester delivered offspring with a reduced median gestational length of 3.4 days. Researchers observed greater median reductions of 4.5 days for the 25th percentile and smaller median reductions of 2.3 days for the 75th percentile of gestational age with daily snuff use compared with no use. Daily smoking during the third trimester was associated with a median gestational length reduction of 2.1 days.

Daily snuff use had a weak association with term birth weight. Median term birth weight was 44 g lower for women who reported daily snuff use during the third trimester compared with women who did not report snuff use. The associations were weaker for women who quit snuff during pregnancy or reported occasional use. Daily smoking during the third trimester was associated with reduced median term birth weight by 294 g.

In addition, daily snuff use resulted in 1.4-fold increased odds of nonspontaneous delivery (OR = 1.4; 95% CI, 1.1-1.9). According to the researchers, this means the association between daily snuff use and shorter gestational length may be mediated by clinical interventions.

“[These findings suggest] that the predominant effect of smoking on fetal growth is not through nicotine but through the additional toxic chemicals in cigarettes or by reduced oxygen supply to the fetus,” the researchers wrote. “Our data confirm a growing body of literature showing that frequent snuff use in pregnancy represents a health concern.”