1 Gita Sloka Every Day - Chapter 14 - Gunatraya Vibhaga Yoga - Sloka 3

The entire content of this mail is from Swami Adidevananda's translation of Ramanuja's  Gita  Bhashya and Swami Chidbhavananda's Bhagavad Gita, both published by Ramakrishna Mission

How is the cycle of birth kept up? The answer comes..

The Process of Birth 3-4

1 Gita Sloka  Every Day - Chapter 14 - Gunatraya Vibhaga Yoga - Sloka 3

Uddhava laments Krishna's Leaving

Mama yonih mahat brahma tasmin garbham dadhami aham I

Sambhavah sarva bhutanam tatah bhavati bharat II sloka 3

मम योनिः महत् ब्रह्म तस्मिन् गर्भं दधामि सहं I 
संभवः सर्व भूतानां ततः भवति भारत II श्लोक 3

My womb is the Mahat Brahma (prakriti); in that I place a germ; thence O Bharata, is the birth of all beings.

In that great brahman forming my womb, I lay the germ. The non-sentientprakriti is alluded to it in the text "Earth, water, fire, air, ether, manas, buddhi and ahankara"- thus my prakriti is eight-fold. (7.4.5). This prakriti is designated here as the great brahman  by reason of its being the cause of modifications like the Mahat, Ahankara etc. In the srutis also, here ans there even, the prakriti is mentioned as great brahman, as in, "He who is all knowing, all wise, whose austerity consists of knowledge - from him are produced this Brahman as also food, ie. the universe of name and form. The higher prakriti, which is the mass of sentient selves, the life principle, is here expressed by the term garbha, the source or womb in which all living things originate. I lay the germ, constituting the mass of conscious things, in that prakriti which forms the womb. From that conjunction of the two, brought about by my will is brought forth the origin of all entities from Brahma down to the tuft of grass.