Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA.
Breast Cancer Res Treat. 2011 Nov;130(1):273-9. doi: 10.1007/s10549-011-1582-3. Epub 2011 May 20.
Previous studies have established that higher birthweight is associated with increased risk of breast cancer. However, the mechanisms underlying this association remain unclear. We explored whether maternal pregnancy weight gain and pre-pregnancy body mass index (BMI), which influence birthweight, are associated with risk of breast cancer in offspring. The Nurses' Mothers case-control study of breast cancer was nested in the Nurses' Health Study I and II cohorts. Mothers of 814 nurses with and 1,809 nurses without breast cancer completed questionnaires with information on pre-pregnancy height and weight, pregnancy weight gain, and other aspects of their pregnancies with the nurse daughters. We calculated odds ratios for breast cancer using conditional logistic regression. Mean pregnancy weight gain was 23 lb, and average pre-pregnancy BMI was 21 kg/m². Mothers' weight gain during pregnancy was not associated with the daughters' risk of breast cancer. Compared to women whose mothers gained 20-29 lb, women whose mothers gained less than 10 lb had a relative risk of 0.92 (95% confidence interval [CI]: 0.62-1.36), adjusting for the age of the nurses. Women whose mothers gained 40 or more pounds had a relative risk of 0.82 (95% CI: 0.55-1.23). Mothers' pre-pregnancy BMI was not associated with the daughters' risk of breast cancer. Women whose mothers had a pre-pregnancy BMI of 30 or more had a relative risk of 0.77 (95% CI: 0.34-1.74) compared to those with BMI less than 20. Additional adjustment for prenatal factors or for nurses' characteristics later in life had no effect on the results. The association between birthweight and breast cancer risk is likely due to factors independent of mothers' weight gain during pregnancy or pre-pregnancy BMI. Because BMIs and pregnancy weight gains were lower in this population than today, we cannot rule out associations for very high pre-pregnancy BMIs or pregnancy weight gains.
先前的研究已经证实，较高的出生体重与乳腺癌风险增加有关。然而，这种关联的机制尚不清楚。我们探讨了影响出生体重的母体孕期体重增加和孕前体重指数（BMI）是否与子女乳腺癌风险有关。护士母亲乳腺癌病例对照研究嵌套在护士健康研究 I 和 II 队列中。814 名患有乳腺癌的护士及其 1809 名未患有乳腺癌的护士的母亲完成了问卷，其中包括母亲孕前身高和体重、孕期体重增加以及与女儿怀孕相关的其他方面的信息。我们使用条件逻辑回归计算了乳腺癌的比值比。平均孕期体重增加为 23 磅，平均孕前 BMI 为 21 千克/平方米。母亲孕期体重增加与女儿患乳腺癌的风险无关。与母亲体重增加 20-29 磅的女性相比，母亲体重增加少于 10 磅的女性相对风险为 0.92（95%置信区间 [CI]：0.62-1.36），调整了护士的年龄。母亲体重增加 40 磅或更多的女性相对风险为 0.82（95% CI：0.55-1.23）。母亲孕前 BMI 与女儿患乳腺癌的风险无关。与 BMI 小于 20 的女性相比，母亲孕前 BMI 为 30 或更高的女性相对风险为 0.77（95% CI：0.34-1.74）。进一步调整产前因素或护士以后生活中的特征对结果没有影响。出生体重与乳腺癌风险之间的关联可能归因于与母亲孕期体重增加或孕前 BMI 无关的因素。由于该人群的 BMI 和孕期体重增加低于今天，我们不能排除非常高的孕前 BMI 或孕期体重增加的关联。
