Ashtangasamgraha 2.4

2.4

The pupil is to be taught until he has reached the end of the treatises, their meanings, and practical procedures. / [He should not study] during unseasonal lightning and thunder, an earthquake, or the appearance of Rāhu;

likewise, horripilation, nausea, drowsiness, bodily debility, excessive salivation, distress in the heart, exhaustion, and thirst.
Gradually, however, in a woman with an evident embryo, there is heaviness only in the belly, sunken eyes and voice, disheveling of the pubic hair, sleep, yawning, fainting, vomiting, loss of appetite, swelling of the feet, craving for sour things, and cravings for various diverse objects.
Immediately following that is the manifestation of fever.

And on this it is said:

Its pacification is ghee, just as water is for a burning house.

Then, having dried the bark properly, one should store it well-concealed.