I admit, I lean toward "hysterectomy, ovaries left in place" as being much more effective (tubals sometimes undo themselves; agents could conceivably bribe or otherwise achieve reversal surgery on the sly; and from what I've read ablation often doesn't completely/permanently eliminate menstruation). My own take on it would involve removing the uterus and implanting a device to bolster oestrogen levels - this being, after all, a universe where fully-functional biomechanical arms exist, and therefore a subdermal slow-release sex-hormone supply would be a piece of cake, technically speaking.

I've seen plenty of fics and meta based on the "scan" image of Bucky which suggest that Bucky has similar implants, generally containing adrenaline and/or incapacitating drugs; why can't the Red Room adapt that to keep their sexpionage agents looking young and sexy? (We pretty much have these now, as birth-control implants! So why can't the Red Room have a more advanced version and have it much earlier? The MCU clearly has a technological development timescale that differs significantly from our universe, so it works for me.)

Or, if we're going with the comics-canon where the Widows have had some serum-esque enhancements, then that's enough handwavium for me. If Steve can freeze solid without suffering cellular destruction and Bucky can fall of a thousand-foot cliff without dying, Natasha can lose a uterus without hitting menopause.

And do I think the movie writers thought about this for more than two seconds? Nope!

Heh, yes, this is ultimately my suspicion, too! :D
Ultimately,