. Author manuscript; available in PMC: 2014 Apr 1.

Published in final edited form as: Occup Environ Med. 2013 Jan 23;70(4):231–237. doi: 10.1136/oemed-2012-101146

Table 3.

Risk of invasive and borderline ovarian tumors, by age at reference date, in association with working the nightshift

	<50 years of age at reference date								≥50 years of age at reference date

	Invasive					Borderline			Invasive					Borderline

	Controls (%)(n=444)		Cases (%)(n=274)		OR^a (95% CI)	Cases (%)(n=172)		OR^a (95% CI)	Controls (%)(n=1388)		Cases (%)(n=827)		OR^a (95% CI)	Cases (%)(n=217)		OR^a (95% CI)
Worked nightshift
Never	326	(73.4)	197	(71.9)		113	(65.7)		1094	(78.8)	611	(78.8)		150	(69.1)
Ever	118	(26.6)	77	(28.1)	1.0 (0.69–1.44)	118	(26.6)	1.38 (0.92–2.05)	294	(21.2)	216	(21.2)	1.32 (1.07–1.63)	67	(30.1)	1.57 (1.13–2.19)
Cumulative nightshift work-years
Never	326	(73.4)	197	(71.9)		113	(65.7)		1094	(78.8)	611	(73.9)		150	(69.1)
4mos-1 yr	26	(5.9)	16	(5.8)	1,06 (0.52–2.15)	12	(7.0)	1.28 (0.61–2.71)	71	(5.1)	39	(4.7)	0.98 (0.65–1.49)	15	(6.9)	1.51 (0.83–2.76)
>1–3 yrs	44	(9.9)	22	(8.0)	0.82 (0.45–1.49)	20	(11.6)	1.28 (0.70–2.34)	77	(5.6)	53	(6.4)	1.26 (0.89–1.84)	15	(6.9)	1.32 (0.73–2.40)
>3–7 yrs	24	(5.4)	28	(10.2)	1.52 (0.81–2.87)	22	(12.8)	2.36 (1.22–4.57)	61	(4.4)	66	(8.0)	2.04 (1.40–2.97)	22	(10.1)	2.34 (1.36–4.01)
>7 yrs	24	(5.4)	11	(4.0)	0.67 (0.30–1.51)	5	(2,9)	0.63 (0.22–1.74)	84	(6.1)	57	(7.0)	1.16 (0.80–1.66)	15	(6.9)	1.29 (0.71–2.33)
unknown	0	(0)	(0)	(0)	-	0	(0)	-	1	(<1)	1	(<1)	-	0	(0)	-

Reference date is the date of diagnosis among cases and a comparable assigned date among controls

Adjusted for age at reference, county, reference year, duration of oral contraceptive use, number of full term pregnancies, and BMI at age 30