Women are bitchier on The Pill.

SCOTUS was actually doing you a favour for The Sisterhood, American women.
The Pill literally makes you a hormonal bitch.

http://www.livescience.com/46937-the-pill-perception-other-women.html

Among the women in the study, the higher the dose of estrogen in the birth control they were using, the more likely they were to rank other women’s appearance as very important to them, the researchers found.

The results of the new study as well as previous research suggest that the way women rank other women’s traits is likely related to the hormones in the contraceptives they are taking, said study researcher Valentina Piccoli, of the University of Trieste in Italy. However, without measuring the women’s hormone levels in the blood, the researchers could not [yet] pinpoint exactly how the hormones may have affected the participants’ rankings of other women, she said. [every pill has side effects]

“This mechanism may be a direct result of the hormones ingested via contraceptive pill use,” or it could result from changes in the body’s natural hormone levels that occur in women using the contraceptive, Piccoli told Live Science.

Previous research has shown a relationship between the levels of estrogen in combined hormonal contraceptives and increased jealousy and so-called “mate-guarding behavior,” in which a person tries to ensure that his or her mate is not interested in pursuing other men or women. The new findings show that estrogen levels may be also be related to women’s paying more attention to potential female competitors, the researchers said.

Piccoli stressed that, in the new study, the researchers did not administer different doses of estrogen but only assessed the doses of the hormone that were in the contraceptives the women took. Therefore, the study does not show a cause-and-effect relationship between the different levels of estrogen and what the researchers have called “objectification” of other women, she said.

The researchers will next look at a larger sample of participants to better understand the results, she said.