Table 3.

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

							Per kg increase in birth weight
Case group	Birth weight	N Cases	Woman-years	HRa	95% CI	p-valueb	HRa	95% CI
Endometrial (n=694)	2.0-3.25 kg 3.26-3.75 kg 3.76-5.5 kg	334 252 108	1,624,649 1,178,348 559,216	0.98 1.00 0.88	(0.84-1.16) (ref) (0.70-1.10)	0.39	1.01	(0.88-1.16)
Type I (n=624)	2.0-3.25 kg 3.26-3.75 kg 3.76-5.5 kg	293 231 100	1,624,649 1,178,348 559,216	0.94 1.00 0.89	(0.79-1.12) (ref) (0.70-1.12)	0.52	1.06	(0.91-1.23)
Endometrioid Adenocarcinoma (n=498)	2.0-3.25 kg 3.26-3.75 kg 3.76-5.5 kg	230 186 82	1,624,649 1,178,348 559,216	0.91 1.00 0.91	(0.75-1.11) (ref) (0.70-1.18)	0.31	1.11	(0.94-1.31)
Other Type I (n=126)	2.0-3.25 kg 3.26-3.75 kg 3.76-5.5 kg	63 45 18	1,624,649 1,178,348 559,216	1.05 1.00 0.80	(0.72-1.54) (ref) (0.46-1.38)	0.90	0.89	(0.64-1.23)
Type II (n=67)	2.0-3.25 kg 3.26-3.75 kg 3.76-5.5 kg	40 19 8	1,624,649 1,178,348 559,216	1.58 1.00 0.85	(0.92-2.73) (ref) (0.37-1.95)	0.56	0.63	(0.40-1.00)

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

^aHR and 95% CI estimated from Cox proportional hazards regression stratified by birth cohort

^bp-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-endometrial cancer associations by Type I/Type II tumors=0.03