A new pilot program in London will make the birth control pill available next month, through pharmacists, without a prescription. It's a big shift from December 1955, when scientists made the first presentation that progesterone can stop women from ovulating, and many states had laws banning the use of contraception.
Despite nearly 50 years of access to the pill, some women are clueless about side effects that doctors might not bother sharing, and some that are just being discovered.
"Doctors in general tend to hesitate to suggest things to the patient," said Dr. Nanette Santoro, director of reproductive endocrinology at the Albert Einstein College of Medicine in New York City and a member of The Endocrine Society.
"These are things that wouldn't have a major health impact."
Santoro said, with limited time in appointments, doctors focus on the major side effects that can pose a health risk: the risk of blood clots among smokers, high blood pressure, and stroke with some migraine headaches, for example.
But Santoro knows of many less-pressing and idiosyncratic side effects from the pill that don't always make it into the doctor's talk.
Women on the pill may suffer a lackluster sex drive, mood swings, or even extra sinus pressure, she said.
"Some women may notice their sinuses are a little stuffier," Santoro explained. "It speaks to the bigger point that pills do affect the mucus production of the body."
That means mucus, whether on the cervix or in the nose, can become thicker.
This August, research began to confirm another strange connection between the birth control pill and a woman's nose.
In a study of about 100 college students in the U.K., scientists found that the pill may change how women find a man's scent sexually attractive.
The study collected body odor from volunteers and put it in jars for the ladies to smell. Among the 200-300 different chemical compounds in sweat, researchers tried to draw a connection to the woman's reaction to the sweat and a by-product in the sweat from the major histocompatibility complex (MHC) genes, which contribute to the body's immune system.
Since the late 1990s, research has shown that women find the scent of a man more attractive if he has MHC genes that are different from their own, and less attractive if he has similar MHC genes.
But that all may change two months after a woman goes on the pill.
"In the pill-using group, there was a significant shift in their preference for men who had more similar odors," said Craig Roberts, a co-author of the August MHC study appearing in the "Proceedings of the Royal Society B," and a lecturer at the University of Liverpool in the U.K.
Roberts said the women in the control group who didn't take the pill only started to find men with different MHC genes more attractive in the second round of body odor sniff tests.
"It's an odd thing to do, smell odors in jars," Roberts said. "We don't know the effects in the real world, but it does carry implications for women who are using the pill, and you can extrapolate from this very artificial laboratory study quite a long way."
For example, "They may choose someone they may not choose otherwise," he said. In theory, Roberts said a woman may choose a man while she's on the pill and feel fine, but subconsciously find her mate less attractive if she goes off the pill.