Reference for Yevamot 200:19

משכחת לה בקידושי טעות וכדרב יהודה אמר שמואל דאמר רב יהודה אמר שמואל משום רבי ישמעאל (במדבר ה, יג) והיא לא נתפשה אסורה הא נתפשה מותרת

A minor, an expectant mother, and a nursing wife. The minor,<span class="x" onmousemove="('comment',' Is permitted the use of an absorbent. ');">⁶²</span> because she<span class="x" onmousemove="('comment',' Were she not to use one. ');">⁶³</span> might become pregnant and, as a result, she might die. An expectant mother,<span class="x" onmousemove="('comment',' Is permitted the use of an absorbent. ');">⁶²</span> because she<span class="x" onmousemove="('comment',' Were she not to use one. ');">⁶³</span>

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