Just came across this - it isn't available yet but pretty interesting how it works

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BLOOM is an elegant, self-inserted temperature sensor that is able to detect the subtle changes that occur before ovulation that other methods are unable to detect, then sends an alert to her smartphone when she is most fertile.
learning your rhythm

BLOOM pinpoints the window of fertility, without having to actively engage in data collection. Simply insert BLOOM ring once per month, and let BLOOM do the rest.
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would you try it?