Kauthumagrihyasutra 8

Now then, the consecration of the fetus: from the sixth day of sexual union onwards, knowing that sons are born on even days, sons are born on even [nights], [and] daughters are born on uneven nights, when it is the bride's first pregnancy, through the consecration of the womb, for the sake of consecrating the offspring about to be born, he should perform the puṃsavana and the sīmantonnayana; counting one month from whatever day conception occurred, in the third month, on an auspicious day, then the puṃsavana; the ancestral offering for prosperity on the preceding day; then, on the following day at dawn, having bathed, having smeared a four-cornered sacrificial ground, sitting upon darbha grass with tips to the north, the wife to the south and the patron of the sacrifice to the north, facing east, the brahmin priest, then having brought forward the fire or without it, having offered the morning oblation, having offered [the rites] from the sweeping up to the introductory formula, having offered the limb of the sacrificial firewood, having then offered with the three mystic utterances; then the patron of the sacrifice, standing behind his wife, should touch her right waist down to the navel, saying 'Two males!'; sitting down in his own place, then having completed the later offerings, the bride having bathed again, the patron of the sacrifice, having placed flowers, unbroken grains, and twenty-one barley grains in a new winnowing basket, taking it, going out from the village, having gone near the king of banyan trees, having approached the goddess residing there, [praying] 'O pervasive with vigour... grant me enduring prosperity, therefore may they fulfil my desire!', having worshipped with flowers and unbroken grains, having scattered barley over it, having cut a branch with its tip to the north using an axe, he should catch that herb either above the ground or in the mid-air; having brought it home with its tip upward, having installed it in the middle of the storehouse or in the place of the water-jar on a proper seat, then having smeared a square sacrificial ground, having performed [the rites] up to the introductory formula, having offered the limb of the sacrificial firewood, and again having offered with the three mystic utterances, having had that herb ground by an auspicious maiden or a brother facing east, taking it as she brings it, the patron of the sacrifice should mutter [the verse]...; then, having made the wife lie down to the west of the fire with her head to the east and face turned upward, the patron of the sacrifice should lie between the bride and the fire facing west; pressing the juice of the paste into the right nostril with the mantra beginning 'punānagnir', having squeezed it out, placing the paste in water, he should give the garment to the brahmin; she should take that juice into her stomach; both sitting in their own places, then having completed the later offerings, then feeding of brahmins, then feeding of brahmins.

KauthGS 9: