Leon D A
Department of Epidemiology and Population Sciences, London School of Hygiene and Tropical Medicine, UK.
Int J Cancer. 1989 Jun 15;43(6):986-91. doi: 10.1002/ijc.2910430606.
The independent effects of parity and age at first birth on breast cancer incidence are investigated in a 1% sample of women aged 16 to 59 from the 1971 Census of England and Wales. Over the period 1971-81, 1,003 breast cancer cases occurred in the cohort of 113,263 women who were either married, widowed or divorced at the time of Census. Age at first birth was positively related to breast cancer risk, women giving birth to their first child after 35 years being at greater risk than nulliparous women. This effect remained, after adjustment for number of live-born children. Breast cancer risk showed a statistically significant decline with increasing parity even after adjustment for age at first birth. These results are consistent with other published evidence which suggests that other births subsequent to the first have an independent effect on breast cancer risk.
利用1971年英格兰和威尔士人口普查中16至59岁女性1%的样本，研究初产时的生育胎次和年龄对乳腺癌发病率的独立影响。在1971年至1981年期间，在普查时已婚、丧偶或离婚的113,263名女性队列中发生了1003例乳腺癌病例。初产年龄与乳腺癌风险呈正相关，35岁后生育第一胎的女性比未生育女性风险更高。在调整活产子女数量后，这种影响依然存在。即使在调整初产年龄后，乳腺癌风险也随着生育胎次的增加而在统计学上显著下降。这些结果与其他已发表的证据一致，表明初产之后的其他生育对乳腺癌风险有独立影响。
