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If she has no past or present history of bleeding during pregnancy
, then she can certainly travel to Thanjavoor. She should not exert herself too much. She should not carry heavy luggage. Reach the station in Hyderabad, well in advance of arrival of the train, so that she does not have to rush to catch the train. Drink plenty of water, eat fresh green leafy vegetables and fruits to prevent hardening of stool, because straining to pass stool has a risk of inducing bleeding.
Wishing her all the best and safe delivery.