Wisborg Kirsten, Kesmodel Ulrik, Henriksen Tine Brink, Hedegaard Morten, Secher Niels Jørgen
Perinatal Epidemiological Research Unit, Aarhus University Hospital, University of Aarhus, Denmark.
Acta Obstet Gynecol Scand. 2003 Oct;82(10):936-41. doi: 10.1034/j.1600-0412.2003.00244.x.
Cigarette smoking has been considered a risk factor for spontaneous abortion, but conclusions from many studies may be impaired by methodological problems. Studies are required that use data on smoking habits collected before knowledge about outcome of pregnancy and in which adjustment is made for potential confounders.
All Danish-speaking pregnant women booking for delivery at the Department of Obstetrics and Gynecology, Aarhus University Hospital, from September 1989 to August 1996 were invited to participate in the study (n=24,608 pregnancies, including 321 spontaneous abortions and 100 induced abortions). Information about smoking habits before pregnancy and during the first trimester was obtained from self-administered questionnaires before the knowledge about pregnancy outcome. Information about spontaneous and induced abortions was obtained from the Danish National Patient Registry. We used Cox regression analyses with delayed entry (left truncation) for analyses, and hazard ratios to express the association between smoking and spontaneous abortion. Multivariate analyses were performed using a model including alcohol and coffee intake during pregnancy, maternal age, marital status, occupation, education, prepregnancy body mass index, and parity.
Overall, 104 (1.3%) of those contributing time at risk in the first trimester experienced a spontaneous abortion in the first trimester, and 217 (0.9%) of those contributing time at risk in the second trimester experienced a second-trimester abortion. We found no association between smoking and first- and second-trimester abortions. Adjustment for alcohol, coffee, maternal age, marital status, occupation, education, prepregnancy body mass index and parity did not change the result substantially.
Our study did not support findings from previous studies of an association between smoking and spontaneous abortion.
吸烟一直被视为自然流产的一个风险因素，但许多研究的结论可能受到方法学问题的影响。需要开展一些研究，这些研究要使用在知晓妊娠结局之前收集的吸烟习惯数据，并对潜在混杂因素进行调整。
邀请了1989年9月至1996年8月期间在奥胡斯大学医院妇产科预约分娩的所有丹麦语孕妇参与该研究（n = 24,608次妊娠，包括321例自然流产和100例人工流产）。在知晓妊娠结局之前，通过自我填写问卷获取妊娠前及孕早期吸烟习惯的信息。自然流产和人工流产的信息来自丹麦国家患者登记处。我们使用带有延迟进入（左截断）的Cox回归分析进行分析，并使用风险比来表示吸烟与自然流产之间的关联。使用一个包含孕期酒精和咖啡摄入量、产妇年龄、婚姻状况、职业、教育程度、孕前体重指数和产次的模型进行多变量分析。
总体而言，孕早期处于风险期的人群中有104人（1.3%）在孕早期发生了自然流产，孕中期处于风险期的人群中有217人（0.9%）在孕中期发生了流产。我们发现吸烟与孕早期和孕中期流产之间没有关联。对酒精、咖啡、产妇年龄、婚姻状况、职业、教育程度、孕前体重指数和产次进行调整后，结果没有实质性变化。
我们的研究不支持先前关于吸烟与自然流产之间存在关联的研究结果。
