Melbye M, Wohlfahrt J, Andersen A M, Westergaard T, Andersen P K
Danish Epidemiology Science Centre, Statens Serum Institut, Copenhagen.
Br J Cancer. 1999 May;80(3-4):609-13. doi: 10.1038/sj.bjc.6690399.
To explore the risk of breast cancer in relation to the length of a pregnancy we tested whether a preterm delivery carries a higher risk of breast cancer than does a full-term delivery. Based on information from the Civil Registration System, and the National Birth Registry in Denmark, we established a population-based cohort of 474 156 women born since April 1935, with vital status and detailed parity information, including the gestational age of liveborn children and stillbirths. Information on spontaneous and induced abortions was obtained from the National Hospital Discharge Registry and the National Registry of Induced Abortions. Incident cases of breast cancer in the cohort (n = 1363) were identified through linkage with the Danish Cancer Registry. The period at risk started in 1978 and continued until a breast cancer diagnosis, death, emigration, or 31 December, 1992, whichever occurred first. After adjusting for attained age, parity, age at first birth and calendar period, we observed the following relative risks of breast cancer for different lengths of the pregnancy: < 29 gestational weeks = 2.11 (95% confidence interval 1.00-4.45); 29-31 weeks = 2.08 (1.20-3.60); 32-33 weeks = 1.12 (0.62-2.04); 34-35 weeks = 1.08 (0.71-1.66); 36-37 weeks = 1.04 (0.83-1.32); 38-39 weeks = 1.02 (0.89-1.17); 40 weeks = 1 (reference). Parous women who had a preterm delivery below 32 weeks gestation had a 1.72-fold (1.14-2.59) increased risk of breast cancer compared with other parous women. In conclusion, a preterm delivery of 32+ weeks gestation did not significantly increase a woman's risk of contracting breast cancer. Only for the very small group of women with preterm deliveries of less than 32 weeks gestation did we observe an increased risk.
为了探究与怀孕时长相关的乳腺癌风险，我们检验了早产相比足月产是否具有更高的患乳腺癌风险。基于丹麦民事登记系统和国家出生登记处的信息，我们建立了一个以人群为基础的队列，纳入了自1935年4月起出生的474156名女性，她们均有生命状态及详细的生育信息，包括活产儿和死产儿的孕周。自然流产和人工流产的信息来自国家医院出院登记处和国家人工流产登记处。通过与丹麦癌症登记处的链接，确定了该队列中的乳腺癌发病病例（n = 1363）。风险期始于1978年，持续至乳腺癌诊断、死亡、移民或1992年12月31日，以先发生者为准。在调整了年龄、生育次数、初产年龄和日历时间后，我们观察到不同怀孕时长的乳腺癌相对风险如下：孕周<29周 = 2.11（95%置信区间1.00 - 4.45）；29 - 31周 = 2.08（1.20 - 3.60）；32 - 33周 = 1.12（0.62 - 2.04）；34 - 35周 = 1.08（0.71 - 1.66）；36 - 37周 = 1.04（0.83 - 1.32）；38 - 39周 = 1.02（0.89 - 1.17）；40周 = 1（参照）。与其他经产妇相比，孕周低于32周的早产经产妇患乳腺癌的风险增加了1.72倍（1.14 - 2.59）。总之，孕周32周及以上的早产并未显著增加女性患乳腺癌的风险。只有在孕周小于32周的极小组别女性中，我们观察到了风险增加。
