Table 3. Multivariatea relative risks (RR) and 95% confidence intervals (CI) of epithelial ovarian cancer according to childhood body fatness and BMI at the age of 18 years, by study population.

	Nurses' Health Study (NHS)			Nurses' Health Study II (NHSII)
	Cases	Person-years	Multivariatea RR (95% CI)	Cases	Person-years	Multivariatea RR (95% CI)
Body fatness at the age of 5 years
1	169	362 320	1.0 (REF)	27	397 883	1.0 (REF)
2	89	205 923	0.97 (0.75–1.26)	36	513 243	1.12 (0.68–1.85)
3	54	155 820	0.78 (0.58–1.07)	38	385 284	1.48 (0.90–2.42)
4	32	96 839	0.74 (0.50–1.08)	17	206 119	1.18 (0.64–2.17)
⩾5	28	67 943	0.87 (0.58–1.29)	13	111 557	1.65 (0.85–3.20)
P for trendb			0.11			0.12
			P for heterogeneityc=0.03
Body fatness at the age of 10 years
1	143	274 838	1.0 (REF)	18	301 794	1.0 (REF)
2	102	233 863	0.87 (0.67–1.13)	32	495 385	1.16 (0.65–2.08)
3	50	158 127	0.64 (0.46–0.88)	36	365 516	1.76 (1.00–3.11)
4	41	116 397	0.72 (0.51–1.02)	29	255 624	1.91 (1.06–3.45)
⩾5	36	105 620	0.69 (0.48–0.99)	16	195 766	1.30 (0.66–2.56)
P for trendb			0.01			0.12
			P for heterogeneityc=0.01
Average body fatness at the ages 5 and 10 years d
1	135	263 830	1.0 (REF)	15	279 639	1.0 (REF)
1.5–2	107	241 430	0.90 (0.70–1.17)	35	495 350	1.44 (0.78–2.64)
2.5–3	61	173 145	0.73 (0.54–0.99)	37	405 487	1.80 (0.98–3.28)
3.5–4.5	43	147 540	0.61 (0.43–0.86)	32	332 410	1.79 (0.97–3.32)
⩾5	26	62 901	0.81 (0.53–1.24)	12	101 199	2.09 (0.98–4.48)
P for trendb			0.04			0.10
			P for heterogeneityc=0.01
BMI at the age of 18 years, kg m −2
<20	204	578 036	1.0 (REF)	38	645 713	1.0 (REF)
20–20.9	95	314 831	0.89 (0.69–1.13)	29	288 710	1.79 (1.10–2.91)
21–22.9	147	427 126	1.02 (0.82–1.26)	38	366 025	1.87 (1.19–2.95)
23–24.9	76	200 613	1.10 (0.84–1.43)	14	169 776	1.46 (0.79–2.71)
⩾25	59	159 473	1.06 (0.79–1.41)	17	170 411	1.57 (0.88–2.79)
P for trende			0.46			0.13
			P for heterogeneityc=0.32

^aMultivariate analyses adjusted for age (continuous), parity (continuous), duration of oral contraceptive use (continuous), tubal ligation history (yes/no), and height (<1.6, 1.6 to <1.65, 1.65 to <1.7, 1.7 to <1.75, and ⩾1.75 m).

^bP value from multivariate model with body fatness as continuous variable.

^cP for heterogeneity by cohort assessed using the DerSimonian and Laird random effects model.

^dAverage childhood body fatness calculated by taking the average of each participant's body fatness at the ages 5 and 10 years.

^eP value from multivariate model with BMI at the age of 18 years modelled as medians of categories.