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

US approves first generic competitor to Mylan's EpiPen

August 16, 2018
US regulators Thursday approved the first generic alternative for the EpiPen, a life-saving emergency allergy medicine, two years after soaring prices for the original version owned by Mylan stoked controversy.

Study: What patients really think about opioid vs non-opioid medications for chronic pain

August 14, 2018
Prescriptions of opioids for chronic pain has increased dramatically since the 1990s in spite of their known harms. Despite a shortage of scientific studies on the long-term effectiveness of opioids such as morphine, oxycodone ...

Doctors nudged by overdose letter prescribe fewer opioids

August 9, 2018
In a novel experiment, doctors got a letter from the medical examiner's office telling them of their patient's fatal overdose. The response: They started prescribing fewer opioids.

Benzodiazepine and related drug prescriptions have increased among young people in Sweden

August 7, 2018
The prevalence rate of prescriptions for benzodiazepines and benzodiazepine-related drugs (BZD)—medications used to treat anxiety, insomnia, epilepsy and other neuropsychiatric conditions—increased by 22% between 2006 ...

Unwise opioids for wisdom teeth: Study shows link to long-term use in teens and young adults

August 7, 2018
Getting wisdom teeth removed may be a rite of passage for many teens and young adults, but the opioid painkiller prescriptions that many of them receive could set them on a path to long-term opioid use, a new study finds.

Behavioral nudges lead to striking drop in prescriptions of potent antipsychotic

August 1, 2018
A study led by Columbia University's Mailman School of Public Health has found that letters targeting high prescribers of Seroquel (quetiapine), an antipsychotic with potentially harmful side effects in the elderly, significantly ...

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.