Table 1. Description of Participating Cohorts^a.

	Nurses’ Health Studyb	Nurses’ Health Study IIc	Sister Studyd	Women’s Health Initiativee	Total
Sample size	81 869	61 261	40 647	73 267	257 044
Included study period	1982-2016	2013-2017	2003-2017	1993-2017	1982-2017
Follow-up time, median (IQR), y	33.2 (20.0-34.0)	3.8 (3.5-3.9)	9.6 (8.4-11.1)	17.4 (8.7-19.9)	11.2 (3.9-21.0)
Age range at assessment for use of powder in the genital area, y	35-62	48-68	35-77	49-81	35-81
Age, median (IQR), y	48 (42-55)	58 (54-62)	55 (48-61)	63 (57-69)	57 (50-62)
All ovarian cancer cases	1258	76	220	659	2213
Medically confirmed ovarian cancer cases	1055	37	172	659	1923
Powder use in genital area, %
Ever	41	26	27	53	39
Long-term		6	6	16	10
Frequent	27	26	7		22

Abbreviation: IQR, interquartile range.

^aMore detailed descriptions of the Nurses’ Health Study and the Nurses’ Health Study II can be found in Bao et al¹⁴; in Sandler et al¹⁵ for the Sister Study; and in Anderson et al¹⁶ for the Women’s Health Initiative.

^bPowder use in the genital area was assessed in the 1982 follow-up questionnaire, not at study baseline. Participants were excluded if they did not respond to the question regarding use of powder in the genital area (n = 28 584), had ovarian cancer prior to responding to the 1982 questionnaire (n = 174), underwent a bilateral oophorectomy at the time of the 1982 questionnaire (n = 10 896), or did not contribute any person-time after the 1982 questionnaire (n = 4). Frequent use was defined as use of powder in the genital area at least once per week. Women who underwent bilateral oophorectomy during follow-up were censored at age of oophorectomy. Follow-up was complete through June 1, 2016.

^cUse of powder in the genital area was assessed in the 2013 follow-up questionnaire, not at study baseline. Participants were excluded if they did not respond to the question regarding use of powder in the genital area (n = 41 141), had ovarian cancer prior to 2013 (n = 287), underwent a bilateral oophorectomy at the time of the 2013 questionnaire (n = 13 739), or did not contribute any person-time after the 2013 questionnaire (n = 1). Frequent use was defined as use of powder in the genital area at least once per week. Long-term use was defined as use of powder in the genital area for 20 years or longer. Because data were reported in 2-year cycles, we did not censor for oophorectomy that occurred after 2013. Follow-up was complete through June 1, 2017.

^dParticipants were excluded if they withdrew from the study (n = 2), had ovarian cancer prior to baseline or unclear ovarian cancer status at baseline (n = 225), underwent a bilateral oophorectomy prior to baseline (n = 9009), or did not respond to any of the questions regarding use of powder in the genital area (n = 1001). Ever powder use was defined as use of powder in the genital area during the 12 months prior to baseline or at ages 10 to 13 years. Long-term use was defined as use of powder in the genital area at ages 10 to 13 years and within the last 12 months. Frequent use was defined as use of powder in the genital area at least once per week (during the last 12 months) or frequently (as termed in the questionnaire) between ages 10 and 13 years. Women who underwent a bilateral oophorectomy during follow-up were censored at age of oophorectomy. Follow-up was complete through September 15, 2017.

^eParticipants were excluded if they did not complete the questionnaire regarding use of powder in the genital area (n = 342), had ovarian cancer before baseline (n = 641) or unknown cancer status before baseline (n = 890), underwent a bilateral oophorectomy at baseline (n = 18 183), or had no follow-up information (n = 353). Long-term use was defined as use of powder in the genital area for 20 years or longer. Postbaseline oophorectomies were not recorded. Follow-up was complete through February 28, 2017.