When it is performed
Seemantonnayana is performed in the seventh or eighth month of pregnancy, during the waxing moon, on a day when the moon is in a male nakshatra by tradition. Regional names differ — Valaikappu in Tamil families, Godh Bharai in North India, Dohale Jevan in Maharashtra — but the samskara is the same.
Purpose
The rite is for the wellbeing of both mother and child, and marks the point at which the household turns its attention to the coming birth. The literal meaning — "parting of the hair" — refers to a gesture the husband performs, parting the wife's hair upward with a porcupine quill or darbha, symbolising growth and protection.
What happens
Punyahavachanam, kalasha pooja, the sankalpa for a safe delivery, the hair-parting gesture, and the bangle ceremony in which sumangalis place glass bangles on the mother-to-be's wrists. The sound of the bangles is held to reach the child.
Preparing
Arrange green and red glass bangles, a new saree, and comfortable low seating. Prepare the mother-to-be's favourite foods — the tradition explicitly honours her cravings. Invite married women of the family for the tamboola exchange.