Phaladeepika
केचिद्यथाधानविलग्नमन्ये शीर्षोदयं भूपतनं हि केचित् । होराविदश्चितनकाययोन्योर्वियोगकालं कथयन्ति लग्नम् ॥ २॥
As regards the correct determining of the Lagna of birth, some opine that it is the time of Adhana or impregnation; others say that it is the time when the head (of the infant) emerges; some others say that it is the time when the child (falls to) touches the ground; while other experts in Astrology hold that it is the time when the child gets itself completely separated from the mother's womb.
english translation
kecidyathAdhAnavilagnamanye zIrSodayaM bhUpatanaM hi kecit । horAvidazcitanakAyayonyorviyogakAlaM kathayanti lagnam ॥ 2॥
hk transliteration by Sanscript