Table 1.

Participant Demographics

Measure	Response	N	% of N or M (SD)	Range
Age (years)		147	24.1 (6.3)	18–43
Race	White	87	59.2%
	Black or African American	13	8.8%
	Asian	32	21.8%
	Native Hawaiian or Pacific Islander	0	0.0%
	American Indian or Alaskan Native	1	0.7%
	Multi-Racial	13	8.8%
	Did not respond	1	0.7%
Ethnicity	Hispanic or Latino	23	15.6%
	Not Hispanic or Latino	124	84.4%
Average number of days bleeding#		146	5.7 (1.3)	3–10
Questions for participants with painful periods only:		116	78.9%
Did period pain start at the time of menarche? *	Yes	60	51.7%
Age (years) that painful periods began (if not at menarche)?		56	16.3 (2.9)	10–28
Years since menarche (first period) without a period? *	Never, always had a regular period	67	57.8%
	Less than 1 year	32	27.6%
	1	8	6.9%
	2	3	2.6%
	3	2	1.7%
	5 to 10	3	2.6%
	More than ten years	1	0.9%
Days of pelvic menstrual pain/month *		116	3.7 (2.0)	1–10
Days of school or work missed in last 3 months *		116	2.2 (3.3)	0–25

Note.

^*participants were administered this question if they answered Yes to painful periods (> 5 out of 10);

^#one participant was not administered this question because she did not report having a period for the last 6 months due to birth control pill use although she had a period before the EEG visit.