Smoking in late pregnancy reduces birth weightBMJ 2006; 332 doi: https://doi.org/10.1136/bmj.332.7539.0-e (Published 23 February 2006) Cite this as: BMJ 2006;332:0-e
Research question How do smoking patterns during pregnancy influence birth weight?
Answer A strong linear relationship exists between maternal smoking in the third trimester and lower birth weight.
Why did the authors do the study? We already know that women who smoke have smaller babies than other women. The authors wanted to find out more about the relative effect on birth weight of smoking at different stages of pregnancy, independent of other factors that influence birth weight such as preterm birth.
What did they do? They recruited 160 pregnant women from antenatal clinics in Vermont, United States, for a cohort study. All participants reported smoking …