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Contraceptive effectiveness of a digital contraceptive with a wearable device vs an oral thermometer
Agathe van Lamsweerde1,2, Anita Nelson3, Kristina Gemzell-Danielsson2,4
1Natural Cycles Nordic AB, Stockholm, Sweden.
Purpose:
To inform contraceptive decisions, we aimed to compare the pregnancy and continuation rates of a digital contraceptive, when paired with temperature data from wearable devices versus from oral thermometers.
Materials And Methods:
We employed prospectively collected data from women who registered to Natural Cycles for contraception between the 1st of August 2022 and the 1st of September 2024. Using Kaplan-Meier curves, we calculated 13-cycle pregnancy rates in typical and perfect use as well as one-year continuation rates. We estimated the association of known demographic characteristics with pregnancy rates using a multivariate Cox proportional hazards model.
Results:
Among the 195 027 presumed fertile women whom we analysed, the unadjusted 13-cycle pregnancy rate for wearable device users was significantly lower than for oral thermometer users both in typical use (4.7% vs 7.3%; p < 0.001) and in perfect use (2.0% vs 2.9%; p < 0.001). However, when adjusting for demographics, measuring with a wearable device rather than a thermometer was not independently associated with pregnancy. We observed one-year continuation rates of 75.8% for wearable device users and 56.4% for thermometer users.
Conclusions:
Findings from this study suggest that combining a contraceptive app with a wearable device rather than an oral thermometer does not affect pregnancy rates when adjusting for socio-demographic variables. However, the substantial increase in continuation implies greater user convenience.
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