Table 1.

Overall sample characteristics

	Observed months among all individuals		Observed months among pregnancy-capable individuals
	N	%	N	%
1 or more messages sent from teen portal
No	659,883	98.8	320,980	98.4
Yes	7,795	1.2	5,081	1.6
Calendar year
2019	216,187	32.4	105,875	32.5
2020	225,521	33.8	110,083	33.8
2021	225,970	33.8	110,103	33.8
Age (years)
13	133,407	20.0	65,036	19.9
14	134,610	20.2	65,705	20.2
15	134,990	20.2	66,212	20.3
16	137,658	20.6	67,178	20.6
17	127,013	19.0	61,930	19.0
Gender
Male sex, not TGD	339,340	50.8	-	-
Female sex, not TGD	317,852	47.6	317,852	97.5
Male sex, TGD	2,277	0.3	-	-
Female sex, TGD	8,209	1.2	8,209	2.5
Race & Ethnicity*
Asian	105,385	15.8	52,865	16.2
Black/African American	71,105	10.6	36,113	11.1
Pacific Islander and Native Hawaiian	17,856	2.7	8,790	2.7
American Indian and Alaska Native	12,999	1.9	6,759	2.1
Hispanic	58,771	8.8	29,234	9.0
White non-Hispanic only	343,707	51.5	167,419	51.3
More than one race**	65,753	9.8	33,654	10.3
Other (not Hispanic)	16,481	2.5	7,703	2.4
No race or ethnicity recorded	66,615	10.0	30,189	9.3
Insurance status
Private (HMO/PPO)	556,220	83.3	272,469	83.6
Medicaid	111,458	16.7	53,592	16.4
Preventive care visit in past 18 months
No	344,812	51.6	167,378	51.3
Yes	322,866	48.4	158,683	48.7
Prior portal use for secure messaging
No	641,417	96.1	309,949	95.1
Yes	26,261	3.9	16,112	4.9
Parent proxy account active
No proxy account, or not active	429,124	64.3	208,921	64.1
Yes	238,554	35.7	117,140	35.9
Total	667,678	100	326,061	100

Abbreviations: TGD = transgender or gender diverse, HMO/PPO: Health Maintenance Organization/Preferred Provider Organization

^*Race/ethnicity categories are not mutually exclusive.

^**More than one race/ethnicity category was reported. These observations are also counted in individual race/ethnicity categories, so percentages will add up to more than 100