"Simantonnayana" is the third `samskara` of the embryo in a pregnant lady in the Hindus. In this rite, the hairs of the pregnant lady are parted. This is performed after the fourth month of pregnancy on the day of moonlight. This should be done only when moon is connected with the stars, which have masculine names like `Punarvasu`, `Pushya`, `Anurvdhas`, `Mula`, `Shravana`, Ashvini` and `Mrighshiras`.

The reason behind "Simantonnayana" ritual is partly practical and partly superstitious. It is believed that a pregnant woman is the target of evil spirits and hence some rites are performed to get rid of them. The `Asvalayana Smriti` preserved this belief. According to this, evil demons come to the pregnant woman during the first pregnancy to consume the foetus. So, the husband of the pregnant woman prays to the goddess `Sri` to protect his lady. The main aim of "Simantonnayana" ritual is to bring affluence and peace to the mother and the child in her womb by reciting the verses.

Another important and practical reason of performing "Simantonnayana" is that from the fifth month of pregnancy the formation of mind of the foetus starts. Since that time the mother needs to avoid any physical shock to the foetus. So the woman is kept in good mood and the husband himself parts and dresses her hair. The pregnant lady is addressed then as `Raka` or "full moon light" or `Supesa` i, e, "of beautiful limbs".

The time of performance of "Simantonnayana" ritual is decided according to the "Grhyasutras" and the astrological works. Astrological books extend the performance of the "Simantonnayana" ritual up to eight months or even up to the birth of the child. If the ritual is performed after the birth of the child then it is considered to be fake one. Astrologically, after the child was born, placing the child on the lap of the mother or keeping it into a box performs this samskara.

The opinion varies among the authorities whether the performance of "Simantonnayana" ritual is needed in every pregnancy or it is only for the first child. It is performed once according to the Asvalayana, Baudhayana, Apastamba and Parasara and they refer it as a `Ksetra Samskara`. They are followed by Harita and Devala and they think as a woman is purified during the first child, the consecutive siblings will be purified automatically. But others say that the `Garbha samskara` should be performed during each conception. On the day of the "Simantonnayana", the mother needs to fast and it is performed under the male constellation. It is started with "Matrupuja", then "Nandisraddha" and offering to Prajapati. Then on a soft chair the mother is seated on the western side of the fire. The husband then parts the hair of the wife upwards i, e, beginning from the front with a bunch of an even number of green Udumbara fruits, three bunches of Darbha grass, a porcupines quill that had three white spots, a stick of the Viratara wood and with a full spindle. This has to be performed along with the recitation of the mantra "Bhur Bhuvah Svah," or with each of the three Mahavyahrtis. Baudhayana recommends two other verses at this moment.

In later years, one more practice started during the "Simantonnayana", in which a red mark on the person of the wife to frighten the demons was given. The husband ties the Udumbura branch around the neck of his wife with a string of three twisted threads. This is done along with the recital-"Rich in sap is this tree; like the tree rich in sap, be thou fruitful". Again Baudhyana recommends use of sprouts in lie of the Udumbura branch. The next step of the "Simantonnayana" is the husband asks the wife to look at the mess of rice, sesame and ghee and to see into it the offsprings, cattle, prosperity and long life for him. According to some authorities, few Brahmin ladies will sit beside the pregnant mother and will utter, "Be mother of heroic sons, be mother of living sons". He also prays saying that may she perform the functions of progeny in such a good way as she sews the clothes etc, with the needle which does not pierce the fingers at the time of sewing. After this the husband asks the two lute players, "Sing ye the King, or if anybody else is still more valiant." Then follows the next stanza, "Soma alone is our King. May this human tribe, dwell on the bank, O (river) whose dominion is unbroken."

Aryans, being a militant race still wishes for heroic sons during the "Simantonnayana" ritual. By reciting the above stanza they try to create a heroic atmosphere and influence the child in the mother`s womb. The ceremony ends by a feast of Brahmins. But the mother remains silent till the stars appear in the sky. After that, she touches a calf, an act indicative of a male issue, then utters the Vyahrtis, Bhus Bhuvah Svah and the lady breaks her silence.

The "Simantonnayana" ritual continues by giving the full respect and entertainment to the participants of the ceremony. The ladies should see off the ladies and the gents should see the gents off as the ceremony ends.