Along with the usual birth chart, called the rashi chart, Vedic astrology employs a number of subtle, harmonic or divisional charts, which are mathematical subdivisions of the birth chart. 
Planetary positions in several divisional charts are considered important for health. Most notable of these are the positions:
- In the drekkana (harmonic third) for Prana and general vitality,
- Navamsha (harmonic ninth) for the connection with the soul and for longevity,
- In the dvadashamsha (harmonic twelfth) for ancestry and congenital influences,
- In the trimshamsha (harmonic thirtieth) for specific diseases and injuries. The navamsha is the most important of these and should be examined in the same way as the basic birth (rashi) chart.
In determining health, a good Vedic astrologer will examine several of these divisional charts with the rashi (birth) and Moon charts.
In addition to these, another specific factor often examined for determining the Ayurvedic constitution is the navamsha sign of the Moon. .
- David Frawley. Ayurvedic Astrology: Self-Healing Through the Stars. — Delhi: Lotus Press, 2007. — 288 p. — ISBN 81-208-3134-9
- In divisional charts each sign is divided up according to certain numbers and the positions of the planets within them are reorganised according to the new sign positions created by the division.
- Pandit nanak Chand Sharma of Delhi, on of modern India’s greatest Ayurvedic doctors, mentioned this.