From PTS dictionary
Gabbhavakanti - conception
Gabbha - (1) a cavity, a hollow, or, seen from its out-
side, a swelling] interior, cavity, an inner room, private chamber, bedroom,
cell.
(2) the contents of the womb, i. e. the embryo, foetus: dasa māse °ṁ kucchinā pariharitvā having nourished the foetus in the womb for 10 months
Avakkanti (f.) [fr. avakkamati] entry, appearance, coming down into, opportunity for rebirth S ii.66 (nāmarūpassa); iii.46 (pañcannaṁ indriyānaṁ); Pug 13 (= okkanti nibbatti pātubhāvo PugA 184); Kvu 142 (nāmarūpassa); Miln 123 (gabbhassa).
Suttas that use the term
Idha, bhante, ekacco asampajāno mātukucchiṃ okkamati; asampajāno mātukucchismiṃ ṭhāti; asampajāno mātukucchimhā nikkhamati. Ayaṃ paṭhamā gabbhāvakkanti.
The translation used Ven. Sujato: conception
Rhys Davids: descension
(DN 28)
Tiṇṇaṃ kho pana, bhikkhave, sannipātā gabbhassāvakkanti hoti… Yato ca kho, bhikkhave, mātāpitaro ca sannipatitā honti, mātā ca utunī hoti, gandhabbo ca paccupaṭṭhito hoti—evaṃ tiṇṇaṃ sannipātā gabbhassāvakkanti hoti.
The translations given for gabbhassāvakkanti
Ven. Bodhi : the descent of the embryo
Ven. Sujato: an embryo is conceived
I. B. Honour : conception
(MN 38)
From Milindapañña;
Kukkuṭānaṃ, mahārāja, vātena gabbhāvakkanti hoti. Balākānaṃ meghasaddena gabbhāvakkanti hoti.
King, Hens get descension through the wind. Cranes get descension with thunder.
This phrase from the milindapañña is controversial. If gabbhāvakkanti means conception; the physically conceiving an embryo above phrase makes no sense.
Gabbhassāvakkanti and gabbhāvakkanti have a same meaning?
What are the meanings of gabbhāvakkanti and gabbhassāvakkanti?