Study raises doubts about safety of some forms of birth control pills

June 28, 2017 by Morgan Sherburne, University of Michigan
Pills. Credit: Public Domain

New research on how birth control pills affect the level of hormones in women's blood serum has found much higher levels of hormones in women who take birth control pills compared to women who don't.

The University of Michigan study was motivated by evidence that risk increases with hormonal exposure. The authors examined seven commonly prescribed birth pills and found that four formulations more than quadruple levels of progestin, a of the hormone progesterone, and another formulation resulted in a 40 percent higher exposure to ethinyl estradiol, a synthetic version of estrogen.

The study's lead author, human evolutionary biologist Beverly Strassmann, stresses that birth control has greatly improved women's lives. But, she says, it's also important to design birth control pills so that they don't contribute to risk for breast cancer. In American women, breast cancer is the most common type of cancer and the second leading cause of death.

"Not enough has changed over the generations of these drugs, and given how many people take hormonal birth control worldwide—millions—the pharmaceutical industry shouldn't rest on its laurels," said Strassmann, professor of anthropology and faculty associate at the U-M Institute for Social Research.

Progesterone and estrogen are both produced by the ovaries and their levels vary naturally over the course of the . The pill replaces these naturally released hormones with synthetic versions. The study's goal was to test whether the synthetic versions increased or decreased hormonal exposure compared to what women might get from their own ovaries.

"That this hasn't been answered is amazing, given that we already know that there's a correlation between hormonal exposure and ," Strassmann said.

Strassman's research pulled data from 12 different studies that measured the amount of estrogen and progesterone over the menstrual cycle in women who don't take the pill.

Strassmann and her co-authors then compared the total levels of estrogen and progesterone in these women to the total levels of synthetic hormones, progestin and estradiol, in women taking one of several commonly prescribed for 28 days. That information was taken from the package inserts for each contraceptive formulation.

The new study follows up Strassmann's previous research on menstruation and reproductive biology in the Dogon people of Mali, West Africa. Dogon women rarely practice control, have an average of nine pregnancies, and often breastfeed children to age 2 years.

Because pregnancy and breastfeeding suppress ovulation, Dogon women have only about 100 menstrual periods during their lifetimes. That number is a sharp contrast to the 400 periods experienced, on average, by Westernized who have about two children and seldom breastfeed for more than one year.

"The increased number of menses is associated with increased hormonal exposure and risk for breast cancer," Strassmann said. "It is critically important to know whether hormonal contraception further exacerbates this risk."

Explore further: Pregnancy not dangerous for women who had breast cancer

More information: Jennie L. Lovett et al. Oral contraceptives cause evolutionarily novel increases in hormone exposure: a risk factor for breast cancer, Evolution, Medicine, and Public Health (2017). DOI: 10.1093/emph/eox009

Related Stories

Pregnancy not dangerous for women who had breast cancer

June 4, 2017
Becoming pregnant after a diagnosis of breast cancer does not raise the risk of the cancer returning, said the largest study of its kind to date, released Saturday at a major cancer conference.

Contraception influences sexual desire in committed relationships

December 8, 2016
Sex is quite wonderful when the goal is to have children. But sex can also serve as a "glue" in a committed relationship.

Birth control pills pose small but significant stroke risk

September 18, 2015
Birth control pills cause a small but significant increase in the risk of the most common type of stroke, according to a comprehensive report in the journal MedLink Neurology.

Recent use of some birth control pills may increase breast cancer risk

August 1, 2014
Women who recently used birth control pills containing high-dose estrogen and a few other formulations had an increased risk for breast cancer, whereas women using some other formulations did not, according to data published ...

Hormonal contraceptives and hair dyes increase breast cancer risk

March 9, 2017
In her recent doctoral dissertation, researcher Sanna Heikkinen from the University of Helsinki and Finnish Cancer Registry evaluates the contribution of the use of hormonal contraceptives and hair dyes to the spectrum of ...

Hormonal contraception may raise depression risk

September 29, 2016
(HealthDay)—Women who use hormonal methods for birth control may have a higher risk of developing depression—and teenagers may be most vulnerable, according to a study published online Sept. 28 in JAMA Psychiatry.

Recommended for you

Mouse model aids study of immunomodulation

November 19, 2018
Because mice do not respond to immunomodulatory drugs (IMiDs), preclinical therapeutic and safety studies of the effects of IMiDs have not been possible in existing types of mice. This has led to an inability to accurately ...

Rapid response inpatient education boosts use of needed blood-thinning drugs

November 16, 2018
A new study designed to reach hospitalized patients at risk shows that a "real-time" educational conversation, video or leaflet can lower the missed dose rates of drugs that can prevent potentially lethal blood clots in their ...

Drug overdose epidemic goes far beyond opioids, requires new policies

November 7, 2018
Most government-funded initiatives to address the overdose epidemic in the United States have targeted opioids specifically and have neglected other drugs that are increasingly implicated in overdoses, such as cocaine and ...

Zebrafish larvae help in search for appetite suppressants

November 2, 2018
Researchers at the University of Zurich and Harvard University have developed a new strategy in the search for psychoactive drugs. By analyzing the behavior of larval zebrafish, they can filter out substances with unwanted ...

FDA OKs powerful opioid pill as alternative to IV painkiller

November 2, 2018
U.S. regulators on Friday approved a fast-acting, super-potent opioid tablet as an alternative to IV painkillers used in hospitals.

Amphetamine-related hospitalizations surged between 2003 and 2015

November 2, 2018
An analysis conducted by Hennepin Healthcare, University of Minnesota School of Public Health and University of Michigan researchers shows amphetamine-related hospitalizations increased more than 270 percent from 2008 to ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.