The purpose of this study is to assess the effectiveness and efficacy of Dynamic Optimal Timing (DOT), an app-based method of family planning that can be used via Android devices, for women who use the method to avoid pregnancy.

This is a prospective, efficacy study of the Dynamic Optimal Timing (Dot), an app-based method of family planning that provides the user with information about her daily probability of pregnancy based on the length of her menstrual cycles over time. To use the app, women enter the first day of their menstrual period. Women are then provided information about their daily risk of pregnancy for that day, which they can then use to avoid having unprotected sex. The study is being conducted by the Institute for Reproductive Health (IRH) at Georgetown University.

The study will examine the relationship between women's use of the Dot method (both perfect and typical use) and their pregnancy outcomes at the end of the study. The study will also look at several additional secondary outcomes, such as perceived partner support for the method, coital frequency during the fertile time, and intention to continue using the method after study discontinuation, as well as several other variables around the acceptability of conducting an efficacy study via an app.

The study will recruit women who have already downloaded the DOT app on their Android phones. The study will only recruit women who have previously set their intent in the Dot app as "avoid pregnancy" and entered their second period start date into the app. Eligible women will be: between 18 and 39 years old, have not been pregnant or used hormonal contraception in the last 3 months, are sexually active in a relationship with a male partner, and desire to avoid pregnancy for at least one year.

Women who are consented and entered into the study will activate a "research module" within the Dot app. This module is essentially an "overlay" to the DOT app. It does not change the app itself in any way, but provides a data platform for researchers to obtain self-reported data from study participants about their daily sexual history and to collect periodic surveys from participants on topics pertaining to the study primary and secondary outcomes. Women who report pregnancy, or who fail to enter a new cycle start date within the 40-day window allowed by the Dot method, will be contacted and sent urine pregnancy tests, to confirm their pregnancy status. Participants will complete a maximum of 13 menstrual cycles (approximately 1 year) in the study.

Inclusion Criteria:

• Have downloaded the Android app and selected to use it for pregnancy prevention and have indicated that they are interested in participating in the study;
• Have provided contact information to learn more about the study or called the call center;
• Are between 18 and 39 at the time of admission;
• Have menstrual cycles between 20-40 days at the time of enrollment
• Are sexually active with a male partner;
• Have not been pregnant or using any hormonal method of family planning within the past three months
• Are willing to install a password or biometric protection on their phone to ensure the confidentiality of their study data; and
• Live in the U.S.

Exclusion Criteria:

Women who do not meet one or more of the inclusion criteria will be excluded from the study.

The population of eligible participants for this study is women who 1) have begun using Dot for pregnancy prevention; 2) entered their second period start date (i.e., have completed one cycle - in whole or in part - of Dot use), and 3) have indicated that their first cycle was 20-40 days long.

1 year, 7 months