Hi all. I had FFS years ago (almost 10 now! Where does the time go?) with an FFS specialist. I had complications and ended up needing major craniofacial surgery (with a different doctor) in 2014 to fix the issue. I am happy to say I am now completely healed and have as good a result as could be expect considering the issues.
Anyway, while I never had hair loss before surgery I did have a high hairline, and like most people when I had my forehead reconstruction done I had a "scalp advancement" at the same time because it was said to be feminizing. This pulled my hairline forward at least an inch and left a linear scar (also revised later) all along my hairline. I wear my hair with a fringe so I really didn't think too much more about it until it came time to have my revision surgery. I was plotting a new hairstyle, and my friend found one we liked, but he then said "Well, it might not work for you, you have a low forehead." And I thought, do I? When I pulled my hair back and really looked at my face I decided that, yes, I did. It was within the range of being acceptable, but I definitely didn't want my hairline ANY lower and told the revision surgeon as much before my procedure. He did a great job of reducing the scarring, as as promised he left my hairline basically where it had been after the first procedure.
This got me interested in how other people who had had FFS looked, and when I checked out a lot of "after" pics I was rather taken aback by what I saw. In too many cases (and this is just my opinion, feel free to disagree with me) scalp advancement surgery had been performed too aggressively or even in cases where it should not have been performed at all. I saw several women who already had low, low hairlines (which can be a masculine trait, not a feminine one) who had their hairlines yanked even lower, leaving them with a very bizarre and unattractive look. One poor woman, who's hairline was low to begin with, ended up with a tiny forehead and a hairline that started about 2 inches above her eyebrows. In other cases prominent surgeons (two in particular, but I will not name names) routinely isolated a strange island of hair in the central hairline and pulled it about as far forward as it would go, creating a very severe window's peak and leaving the rest of the hairline with an exaggerated recession. No only did this not look feminine (to me) but it did not look like any normal hairline I have ever seen. Even in the best cases, scalp advancements tend to leave a very straight-across frontal hairline but don't really do anything for the M-shaped recession most people assigned male at birth have.
It has been pointed out by others (one woman in particular, but I forget who) that many times it's not so much how "low" your hairline is that makes you look feminine but the SHAPE. Many women seem to have a higher central hairline but overall have an inverted "U" shape to the forehead, with no recession at the sides. Men, on the other hand, tend to have a lower central hairline but then have recession back over the temples. Merely lowering the hairline in every case is NOT feminizing and can actually make one look more masculine. In my opinion, in many cases surgeons would do better to leave the central hairline alone and work on using transplants or something to fill in the thinning sides and create a more feminine shape.
Obviously this is kind of a case-by-case thing; some people, even people assigned female at birth, do have very high hairlines that throw off their facial proportions. In that case it makes sense to lower the hairline so the forehead doesn't seem too expansive for the rest of one's features. I did have a high forehead before, and though had I the chance to do it over I would tell the surgeon not to lower my hairline SO much, I don't regret having it done. Unfortunately I had some hair loss due to surgery/scarring around the temples, and for years I've been considering having transplants to just a small area on either side to give me more of an inverted "U" and hide the scarring. I just think women considering FFS should be aware of this issue and really do some reading up on facial proportions BEFORE submitting to a scalp advance, as as I mentioned they are not always feminizing and can have the opposite effect. It is possible to leave the hairline unchanged or even raise it higher during forehead surgery (through the same incision) so it pays to know what you want ahead of time and have a lot of communication with your doctor so you are both on the same page.
Obviously these are just my observations, but I think if you look at a lot of pictures of female vs. male hairlines you will see what I mean. To each their own, though, and what matters most is what makes YOU happy.