Three years ago I discussed several Swedish studies
reporting that pregnant women who use snus are at risk for (1) slightly smaller
babies and premature delivery and preeclampsia (here); and (2) premature birth and stillbirth (here). Although the risks were lower than
those from smoking, I advised that “pregnant women should refrain from using
all tobacco products.”
A new Swedish study confirms that the effect of snus use on
birth weight is small, but the researchers made a gross oversight in their
journal article.
The new study was conducted at Lund University and was based
on over 900,000 births chronicled in the Swedish Birth Registry from 2002 to
2010. It looked at the effect of snus
use on birth weight with a conventional analysis and with a special analysis in
which mothers had used or not used snus during two different pregnancies (a “sibling
analysis”).
Conventional analysis found that snus users’ babies weighed
a statistically significant 47 grams (about 1.7 ounces) less than those of
never users. This is approximately the
same magnitude found in the earlier study I discussed (here). However, there was only a 20 gram
reduction in the sibling analysis, which was not significant.
The Lund authors emphasize: “Our findings should not be
interpreted as suggesting that the use of snus is a healthier alternative to
smoking during pregnancy…” This might be
an appropriate statement, but for the fact that the researchers report no
attempt to compare and analyze the data they held on the births experienced by
more than 100,000 smokers.
Exaggerating small risks but failing to directly compare smokeless
tobacco users with smokers seems to be endemic among many scientists with
anti-tobacco leanings. Datasets from the
Karolinska Institute and the American Cancer Society contain risk information
for both smokeless users and smokers, but staff at these organizations refuse
to report comparable risks for these two groups.
The Lund University study appears in PLoS (Public Library of
Science) One (here). The publisher banned studies funded
by the tobacco industry, a policy I labeled as unscientific three years ago
(here).
3 comments:
I've never understood this whole birth weight argument. I was the first born and weighed less than 7lbs. My sister was the third born and weighed 8lbs. 20 gms is less than 1 oz. Am I worse off? I'm now 56 years old, fine boned, 6' 1.5" with a bmi of 22. When I was born, my weight wasn't considered abnormal, yet now, babies are monsters. Can somebody please explain all this?
@Jonathan I believe when people discuss birth weight and being small, they are also thinking that the baby is premature, which could mean health complications.
I think that their conclusion that "snus is a healthier alternative to smoking during pregnancy" is a dumb statement to make. Just because it's healthier than smoking does not make it healthy, which is how a lot of people will take that statement.
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