Researchers at UC Irvine have discovered a connection between hormonal contraception and the way memory works in women:
The birth control pill, taken by more than 100 million women worldwide, appears to impact how the brain remembers events. Those taking the pill will recall more of the emotional aspects of an occurrence, while non-users will hold onto more factual details…the impact makes sense, according to the research team. Birth control pills work by suppressing the natural production of hormones estrogen and progesterone, which have already been associated with strong “left brain” memory skills — the part of the brain responsible for fact retrieval.
The findings may also contribute to a better understanding of PTSD:
[T]he findings could help lead to fuller answers about why women experience post traumatic stress syndrome more frequently than men, and how men remember differently than women. Men typically rely more on right-hemisphere brain activity to encode memory. They retain the gist of things better than details. Women on the pill, who have lower levels of hormones associated with female reproduction, may remember emotional events similarly to men.