Here, according to what I brought in one of the nearby answers regarding the use of a diaper on Shabbat, the yellow stripe changes on Shabbat when the baby is wet, there are opinions among the judges that it is prohibited, but they agree here as well that the color changes when ovulation turns out to be real will also be prohibited here, and if it does not occur, then it is something that is not It is forbidden to encourage, and it must also be discussed what the fence is of being fulfilled, and even those who allowed it on a baby may get stricter here, because here he wants the color, since he cannot claim neither that he does not intend nor that he did not allow her nor that he does according to his will, since this is his whole purpose in using the kit The one that the stripe will color according to the situation and according to that the reality will be known.
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