The tiny amygdala buried deep in each half of our brains has a lot to do with our emotions and our emotional memories. And sex hormone levels drive a lot of the amygdala's responses, as you may have noticed when a dirty athletic sock on the kitchen table set off bottle rockets just before your period.
Nicole Petersen (UCLA and UC Irvine) and Larry Cahill (UC Irvine) wondered what happens when we dramatically lower circulating sex hormone levels by replacing them with their analogs in birth control pills. So they used functional magnetic resonance imaging (fMRI), the favorite tool of today's behavioral neuroscientists, to compare what happens to women who cycle naturally or under the control of a daily pill as the researchers sadden, anger, or disgust them.
(Don't you wish you could get paid to do such things?)
Here's the takeaway: while you're on the pill, you are harder to upset. Very likely, given what else scientists know about the amygdala, you are also likely to remember less about the upsetting event.
To which I would add: warn your spouse not to take personally what happens when you first quit the Pill. And maybe consider in this new light your can't-let-go-of-it memory of something crummy your husband did while you were pregnant. Maybe the comparative intensity of the memory has little to do with the actual event.
Here's the abstract for the report in the September 2015 issue of Social Cognitive and Affective Neuroscience: http://scan.oxfordjournals.org/content/10/9/1266.abstract.