योनिलिंगस्वरूपेण शिवो जन्मनिरूपकः । तस्माज्जन्मनिवृत्त्यर्थं जन्म पूजा शिवस्य हि ८६ ।
Śiva exemplifies birth in as much as He has the form of both Yoni (vaginal passage) and Liṅga (Penis). Hence in order to ward off births the Janmapūjā is of Śiva alone.