Open AccessA Prospective Study of Smoking and Pregnancy
Author(s) -
Kullander Stig,
Källén Bengt
Publication year - 1971
Publication title -
acta obstetricia et gynecologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.401
H-Index - 102
eISSN - 1600-0412
pISSN - 0001-6349
DOI - 10.3109/00016347109157292
Subject(s) - medicine , pregnancy , obstetrics , birth weight , prospective cohort study , parity (physics) , head circumference , low birth weight , pediatrics , surgery , genetics , physics , particle physics , biology
A prospective study was performed on the effect of smoking on pregnancy, using information from 6 363 pregnancies with known smoking habits. Of these, 2806 (44%) smoked during pregnancy, and 2731 (97%) of the 2 806 reported that they smoked during the whole pregnancy. The well‐known effect on prematurity rate and mean birth weight was verified in this study. A 50% increase of prematurity rate was registered among smoking women compared with non‐smoking women. The mean birth weight reduction was 170 g among live‐born, non‐malformed children. These effects were found to occur irrespective of other variables studied: maternal age, parity, and whether the pregnancy was wanted. The body length, head circumference, and shoulder circumference were found to be reduced in children born to smoking women. Placental weight was also reduced, but the ratio placental weight over body weight increased with smoking. No effect on the malformation rate was observed, but the series is too small to exclude a teratogenic effect of smoking. Children were followed to 1 year of age. The death risk for a child of a smoking woman was found to be increased to 1.6 times that for a child of a non‐smoking woman. No significant difference in stillbirth rate was found, but an effect was found on neo‐natal death both before and after the age of 1 week, although only among non‐premature children. Among children dying before the age of 1 week, a significant increase in frequency of abruptio placentae was noted. No other specific cause of death was noted. An overall increased risk of spontaneous abortion among smoking women was verified; this was shown to be almost completely due to the association between the fact that the pregnancy was unwanted and smoking. An even higher incidence of smoking was seen among women with induced abortions. Spontaneous abortion is also associated with unwanted pregnancies, perhaps due to the presence of induced abortions among the group recorded as spontaneous abortions. Smoking was shown to be associated only with late spontaneous abortions. If there is an abortifacient effect of smoking, it must be very slight. The decreased rate of preeclamptic complications among smoking women, described by earlier authors, was verified. A similar decrease in frequency of morning sickness was also found. No effect of smoking on the mean Apgar score of surviving, non‐malformed children was seen. The sex ratio among children born to smoking women differed slightly from that born to non‐smoking women, but this difference was not statistically significant.