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Table 4 Relative risks for breast cancer by average childhood body fatness, with adjustment for later body mass index and menstrual cycle characteristics, among 109,267 premenopausal Nurses' Health Study II participants (1989–2001)

From: Body fatness during childhood and adolescence and incidence of breast cancer in premenopausal women: a prospective cohort study

 

Average childhood figure (ages 5–10 years)

P for trendd

 

1

1.5–2

2.5–3

3.5–4.5

≥ 5

 

Multivariate RR (95% CI)a

1.00

0.93 (0.79–1.08)

0.90 (0.76–1.06)

0.81 (0.68–0.96)

0.48 (0.35–0.65)

<0.0001

Multivariate RR + later BMIb

   BMI at age 18 years

1.00

0.95 (0.81–1.11)

0.95 (0.80–1.12)

0.87 (0.72–1.05)

0.53 (0.38–0.73)

0.004

   Current BMI

1.00

0.93 (0.80–1.09)

0.92 (0.78–1.08)

0.84 (0.70–1.01)

0.51 (0.37–0.69)

0.0003

   Cumulatively averaged BMI

1.00

0.94 (0.81–1.10)

0.93 (0.79–1.10)

0.86 (0.72–1.03)

0.52 (0.38–0.71)

0.001

Multivariate RR + age at menarche and menstrual cycle characteristicsc

   Age at menarche

1.00

0.93 (0.80–1.09)

0.89 (0.76–1.05)

0.80 (0.67–0.95)

0.47 (0.34–0.64)

<0.0001

   Age at menarche, time until regular cycles

1.00

0.93 (0.80–1.09)

0.89 (0.76–1.05)

0.80 (0.67–0.95)

0.47 (0.34–0.64)

<0.0001

   Age at menarche, regularity/length of cycles, ages 18–22 years

1.00

0.93 (0.80–1.09)

0.89 (0.76–1.05)

0.79 (0.67–0.95)

0.47 (0.34–0.64)

<0.0001

  1. aAdjusted for age (months), time period (6 periods), birthweight (<5.5, 5.5–6.9, 7–8.4, 8.5–9.9, ≥ 10 lb), height (inches), recent alcohol consumption (0, 0.1–1.4, 1.5–4.9, 5.0–9.9, ≥ 10 g/day), parity and age at first birth (nulliparous, 1–2 pregnancies with age at first birth <25 years, 1–2 pregnancies with age at first birth 25–29 years, 1–2 pregnancies with age at first birth ≥ 30 years, ≥ 3 pregnancies with age at first birth <25 years, ≥ 3 pregnancies with age at first birth 25–29 years, ≥ 3 pregnancies with age at first birth ≥ 30 years), oral contraceptive use (never, past use <4 years, past use ≥ 4 years, current use <4 years, current use ≥ 4 years), history of benign breast disease (yes, no), and first-degree family history of breast cancer (yes, no). bAdjusted for same factors as above, plus later body mass index (BMI) variables individually, each modeled as medians of the categories. Cumulatively-averaged BMI is the cumulative average of BMI at age 18 years and all subsequent BMI reports up until the current time period. cAdjusted for same factors as above (not including later BMI), plus menstrual cycle characteristics. Age at menarche modeled as continuous. Time until onset of regular cycles (<1 year, 1–2 years, ≥ 3 years, never) and cycle regularity and length from ages 18–22 years (regular <26 days, regular 26–31 days, regular ≥ 32 days, irregular <26 days, irregular 26–31 days, irregular ≥ 32 days) modeled as indicator variables. dWald test of coefficient for body fatness modeled as an ordinal variable. CI, confidence interval; RR, relative risk.