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. Author manuscript; available in PMC: 2019 Mar 1.
Published in final edited form as: Gynecol Oncol. 2018 Jan 11;148(3):547–552. doi: 10.1016/j.ygyno.2017.12.031

Table 2.

Birth weight associations with ovarian cancer, overall and by subtype, Copenhagen School Health Records Register, follow-up from 1978-2014.

Per kg increase in BW
Case group Birth weight categories N Cases Woman-years HRa 95% CI p -valueb HRa 95% CI
Epithelial ovarian
(n=666)		 2-3.25 kg
3.26-3.75 kg
3.76-5.5 kg		 331
193
142		 1,707,386
1,240,235
590,186		 1.27
1.00
1.51		 (1.06-1.52)
(ref)
(1.21-1.87)		 0.0002 – –
Serous
(n=360)		 2-3.25 kg
3.26-3.75 kg
3.76-5.5 kg		 185
89
86		 1,707,386
1,240,235
590,186		 1.54
1.00
1.98		 (1.19-1.98)
(ref)
(1.47-2.67)		 0.0001 – –
Endometrioid
(n=67)		 2-3.25 kg
3.26-3.75 kg
3.76-5.5 kg		 28
26
13		 1,707,386
1,240,235
590,186		 0.79
1.00
1.03		 (0.46-1.34)
(ref)
(0.53-2.01)		 0.56 1.11 (0.71-1.74)
Clear cell
(n=29)		 2-3.25 kg
3.26-3.75 kg
3.76-5.5 kg		 11
15
3		 1,707,386
1,240,235
590,186		 0.54
1.00
0.41		 (0.25-1.18)
(ref)
(0.12-1.41)		 0.32 1.25 (0.64-2.46)
Mucinous
(n=75)		 2-3.25 kg
3.26-3.75 kg
3.76-5.5 kg		 35
21
19		 1,707,386
1,240,235
590,186		 1.23
1.00
1.87		 (0.71-2.10)
(ref)
(1.00-3.48)		 0.75 1.31 (0.87-2.00)
Other epithelial
(n=135)		 2-3.25 kg
3.26-3.75 kg
3.76-5.5 kg		 72
42
21		 1,707,386
1,240,235
590,186		 1.29
1.00
1.01		 (0.88-1.89)
(ref)
(0.60-1.71)		 0.45 0.81 (0.59-1.12)

HR, hazards ratio; CI, confidence interval; kg, kilogram

a

HR and 95% CI estimated from Cox proportional hazards regression stratified by birth cohort.

b

p-value for linearity using the likelihood ratio test for linear splines with 2 knots positioned at 3.25 and 3.75 kg

p-value for heterogeneity of birth weight-ovarian cancer associations across subtype=0.37