Ehh I don't see it. There's no currently known physical mechanism for it. If you say that it has to do with naturalistic factors during birth, fine...but how does that tie into events that happen to you when you're 98 years old? What would be the mechanism for carrying the astronomical positions of the planets with you for your entire life? Shouldn't conception matter more?
Conception should matter more, but both Babylonian and Hellenistic astrologers were in agreement that the time of birth was in agreement with the time of conception. This seems plausible in a naturalistic way, nature gives birth at a time when it is ripe for doing so. This time is influenced by genetics and environment, and after conception/birth, vice versa, genetics and environment influence times of events.
I've seen some people posit that the mechanism is light. Ok cool. So how does that tie into using astrology to predict things like earthquakes and famines? I'd really like to understand the mechanism of a solar eclipse causing an earthquake.
That doesn't seem to be the case. Maybe the solar eclipse causes particular gravitational influence through the syzygy, or meteorological influence through the very short time of obscuration (maybe even this could be responsible for tectonic effects, although IIRC scientists have not found correlation between weather and earthquakes so far).
The Babylonians seemed to have saw what they were doing as omen watching. I contend that astrology, even today with everything that's been built on top of it, is still celestial omen watching....as uncomfortable as that might be to admit. Almost all of the significations of the planets derive from things like their appearance and speed. Mars signifies war because it's a bloody red planet, Saturn is malefic because it is dark and dull in the sky while Venus and Jupiter are bright and shiny. Even now on the cusp of the 2020's I think we're still doing omen watching, as sophisticated and "scientific" as it tries to look.
That is plausible. But a lot of significations in Hellenistic astrology were derived from their temperament and their supposed influences on the four elements in the atmosphere. Like for example, solar radiation does in fact cause hot weather, and hot weather does in fact increase violence - Anderson, C. A., Anderson, K. B., Dorr, N., DeNeve, K. M., & Flanagan, M. (2000). Temperature and aggression. In M. P. Zanna (Ed.), Advances in Experimental Social Psychology. San Diego: Academic Press.
As astrologers it might be best to leave the physics to the physicists and just get on with our weird craft.
Even if astrology was based on omens (which I do not think it is), the correlation of the omens and terrestrial events would be controlled by a third physical factor. Some have invented wild metaphysical speculations like synchronicity and gods that are less plausible than the natural subject, others have contended with psychological explanations of cold reading, but are afraid to say so, these have taken the guise of ''magical divination'' in the eyes of the vulgar, when the hypocrites meant something else, but they are always talking sideways to avoid being discovered and ostracized by the first fellows.