Wisborg K, Henriksen T B, Hedegaard M, Secher N J
Department of Obstetrics and Gynaecology, Aarhus University Hospital, Denmark.
Br J Obstet Gynaecol. 1996 Aug;103(8):800-5. doi: 10.1111/j.1471-0528.1996.tb09877.x.
To evaluate the association between smoking during pregnancy and preterm birth.
A follow up study.
Department of Gynaecology and Obstetrics, Aarhus University Hospital, Denmark.
Four thousand one hundred and eleven nulliparous women with singleton pregnancies who returned questionnaires about smoking habits at 16 weeks of gestation.
The overall rate of preterm delivery was 4.3%. Smokers had a 40% higher risk of preterm birth compared with nonsmokers. A dose response relationship was found between smoking and risk of preterm birth. Adjustment for women's height, prepregnancy weight, age of the mother, marital status, education, occupational status, and alcohol intake did not change the results. Among women with an intake of less than 400 mg of caffeine per day no difference in the risk of preterm birth between smokers and nonsmokers was found. However, among women with an intake of more than 400 mg of caffeine per day, the risk of preterm birth was increased almost threefold among smokers compared with nonsmokers. Furthermore, among women with a high intake of caffeine a dose-response relationship was found; women smoking one to five cigarettes per day had no increased risk of preterm birth compared with nonsmokers with the same intake of caffeine, women smoking six to ten cigarettes per day had almost three times higher risk of preterm birth, and women smoking more than 10 cigarettes per day had almost five times higher risk of preterm birth compared with nonsmokers with the same intake of caffeine.
Smoking increases the risk of preterm birth. The association between smoking and preterm birth was only present among women with a high intake of caffeine. However, whether smoking alone influences the risk of preterm birth among heavy consumers of caffeine needs further investigation.
评估孕期吸烟与早产之间的关联。
一项随访研究。
丹麦奥胡斯大学医院妇产科。
4111名单胎妊娠的初产妇，她们在妊娠16周时返回了关于吸烟习惯的问卷。
早产的总体发生率为4.3%。吸烟者早产的风险比不吸烟者高40%。发现吸烟与早产风险之间存在剂量反应关系。对女性的身高、孕前体重、母亲年龄、婚姻状况、教育程度、职业状况和酒精摄入量进行调整后，结果没有改变。在每天咖啡因摄入量低于400毫克的女性中，吸烟者和不吸烟者的早产风险没有差异。然而，在每天咖啡因摄入量超过400毫克的女性中，吸烟者的早产风险比不吸烟者增加了近三倍。此外，在咖啡因摄入量高的女性中发现了剂量反应关系；每天吸1至5支烟的女性与咖啡因摄入量相同的不吸烟者相比，早产风险没有增加，每天吸6至10支烟的女性早产风险几乎是其三倍，每天吸超过10支烟的女性与咖啡因摄入量相同的不吸烟者相比，早产风险几乎是其五倍。
吸烟会增加早产风险。吸烟与早产之间的关联仅在咖啡因摄入量高的女性中存在。然而，仅吸烟是否会影响咖啡因大量摄入者的早产风险需要进一步研究。
