Of course if they need an abortion after 15 weeks it’s generally due to health related problems or problems accessing healthcare.
there's financial implications too. as we heard this morning, abortions aren't cheap. $600 + other fees and expenses. ~40% of the country can't handle a several hundred dollar expense out of the blue. i'm going to posit that women most likely to have abortions (afaik generally younger and poorer) heavily fall into that percent. and younger women are also less likely to realize they may be pregnant until they're deeper into a missed cycle.
so, there's lead time to realize that a person is pregnant, there's lead time to then save money, there's also arranging one's schedule to get off work, travel to provider, more time for any waiting periods and procedural hurdles that states have already implemented, etc. and that's assuming a pregnant person immediately decides they're going to have an abortion.
now, most abortion happen by the 21st week. abortions after that are generally due to complications. no idea how many abortions happen between 15 and 21 weeks. but for those that happen toward the end of that period, moving to 15 might cut the maximum lead time in half for a lot of women.