Janaashucha is the period of impurity after birth in family. Manu Smriti prescribes Janashucha for the period of 10,12,15,30 days for the four Varnas respectively
A Brahmana shall be pure after ten days, a Kshatriya after twelve, a Vaisya after fifteen, and a Sudra is purified after a month. ManuSmriti 5.83.
Applicability of Ashucha for Sapindas is upto 7 Generations in Family tree.
But the Sapinda-relationship ceases with the seventh person (in the ascending and descending lines), the Samanodaka-relationship when the (common) origin and the (existence of a common family)-name are no (longer) known. ManuSmriti 5.60
The Applicability of Ashucha is to the all the Sapindas according to verse 5.61
As this impurity on account of a death is prescribed for (all) Sapindas, even so it shall be (held) on a birth by those who desire to be absolutely pure. Manu Smriti 5.61
In very next verse i.e. 5.62 the smriti contradicts itself saying that Ashucha period is only for Parents of the new born jiva connecting it with all sapindas who need absolute purity.
(Or while) the impurity on account of a death is common to all (Sapindas), that caused by a birth (falls) on the parents alone; (or) it shall fall on the mother alone, and the father shall become pure by bathing; Manu Smriti 5.62
Which verse should be used to decide Janana(Birth) Ashoucha period in family? Is it okay if we ignore Janan Ashucha as its only applicable to Parents?