This question came up in the Online 10-day Retreat Nov 3, 2020, guided by Delson Armstrong. Day 5 was part of a daily 30-minute discussion on the suttas, the Dhamma talk and reflections.
Slightly edited to improve readability
Birth can be looked at in two different ways. That is to say, death is just determination of life, the termination of the bodily processes, and the mental processes. That's the dissolution of the body, let's make sure that we're clear on that, first and foremost.
Birth can be seen as birth of action, which is the Kamma coming into play, where you are having a sense of self that you are doing something. That's the birth of action in one regard, and that happens continuously through just one lifetime. It can happen a trillion times because of the different actions that are happening with the intention, and so on and so forth.
Then the birth of, let's say, a being. Being is basically bhava, which is really the accumulated tendencies. When you see the idea of a sense of self, it's really all just this bundle of Kamma. It's a bundle of different associations, a bundle of different ideas and concepts and mindsets, that create the sense of self. It's all of these tendencies that you take together and that's the accumulated tendencies that creates this sense of being. But you take that all away and there is no being, there is no permanent being there. It's always changing, so when you have that sense of being and act from that sense of being. there is the birth of action.
In the case of rebirth on the macro level, where you're looking at Dependent Origination from that viewpoint, there is the being that is being conceived in the womb, in the case of a human birth. In the previous life, what happens is because of the Formations that arise at the point of death, in the deep layers of mind, there is craving or attachment to one of those Formations.  The consciousness that is carried forward through those Formations, then intends for rebirth. That creates the intention for rebirth. Then, those Formations are carried forth by that consciousness, which spontaneously links at the point of conception, which will then create the mentality and materiality. Which is in this case the fetus that grows in the womb. And there is already a sense of being and the Formations are starting to grow, and different Formations are starting to come into being, based on the experience of the fetus in the womb. So, there is still craving, there is still clinging because of the sensory inputs that start to arise when the sixth sense bases start to become developed, during the nine-month process of the conception of that being, of the making up of that being. That is ‘being’, that is becoming. Now that being is becoming, that's the process of becoming a bhava. And then, birth happens, which then creates the birth of that being into this world, into this physical world. That's one way to look at it through the process of macro level rebirth.
There's a comment here in the chat that says: Even earlier than the fetus, the Buddha talks about the descent in the womb.
Basically, that's referring to when the consciousness that arises because of taking the previous Formation as personal and craving for it. That carries forward the consciousness, which will then descend into the womb. That will create, at conception, that being, that sense of being. But as soon as that consciousness takes root in that new mentality-materiality at conception, that consciousness dissipates and a new consciousness arises, based on the experience of that being. Even within the womb, already at conception, there's trillions of arising's and passing away's of consciousnesses going on within that womb. It's not the very same consciousness that continues to be experiencing things within the womb. It's just that consciousness keeps arising and passing away in that fetus as well.