Apastambagrihyasutra 6.14: caturdaśaḥ khaṇḍaḥ

The Sîmantonnayana (or parting of the pregnant wife's hair, is performed) in her first pregnancy, in the fourth month.

(The husband) serves food to Brâhmanas and causes them to pronounce auspicious wishes; then, after (the ceremonies) from the putting (of wood) on the fire down to the Âgyabhâga oblations (have been performed), he offers the oblations (indicated in the) next (Mantras, M. II, 11, 1-8), while (the wife) takes hold of him, and enters upon the (performance) of the Gaya and following oblations.

Having performed (the rites) down to the sprinkling (of water) round (the fire), he makes her sit down to the west of the fire, facing the east, and parts her hair upwards (i.e. beginning from the front) with a porcupine's quill that has three white spots, with three Darbha blades, and with a bunch of unripe Udumbara fruits, with the Vyâhritis or with the two next (verses, II, 11, 9. 10).

Of the next two (verses, II, 11, 11. 12) the first (is to be sung on this occasion) among the (people of the) Sâlvas.

The second (is to be used) for Brâhmanas; and the river near which they dwell is to be named.

He ties barley-grains with young shoots (to the head of the wife); then she keeps silence until the stars appear.

When the stars have appeared, he goes (with his wife) towards the east or north, touches a calf, and murmurs the Vyâhritis; then she breaks her silence.

The Pumsavana (i.e. the ceremony to secure the birth of a male child) is performed when the pregnancy has become visible, under the constellation Tishya.

From a branch of a Nyagrodha tree, which points eastward or northward, he takes a shoot with two (fruits that look like) testicles. The putting (of wood) on the fire, &c., is performed as at the Sîmantonnayana (Sûtra 2).

He causes a girl who has not yet attained maturity to pound (the Nyagrodha shoot) on an upper mill-stone with another upper mill-stone, and to pour water on it; then he makes his wife lie down on her back to the west of the fire, facing the east, and inserts (the pounded substance) with his thumb into her right nostril, with the next Yagus (II, 11, 13).

Then she will give birth to a son.

Here follows the ceremony to secure a quick deliverance.

With a shallow cup that has not been used before, he draws water in the direction of the river's current; at his wife s feet he lays down a Tûryantî plant; he should then touch his wife, who is soon to be delivered, on the head, with the next Yagus (II, 11, 14), and should sprinkle her with the water, with the next (three) verses (II, 11, 15-17).

Yadi garâyu na pated evamvihitâbhir evâdbhir uttarâbhyâm (II, 11, 18. 19) avokshet.