Women medical experts, theologians and writers joined voices in rejecting a Los Angeles Times editorial by a prominent birth control advocate who criticized Catholic morality and claimed that nuns should take birth control for their health.

Marie Hilliard, director of bioethics and public policy at the National Catholic Bioethics Center, says hormonal contraceptives pose "substantial threats" to all women, including myocardial infarction, cerebral-vascular accidents, deep venous thrombosis and pulmonary embolism.

If the pill is so beneficial, she asked, "why are not all of us being prescribed them by our physicians, regardless of one's sexual behavior?"

"It is because there are documented risks by the National Cancer Institute that call for a prudential use of such hormones," she told CNA Jan. 5.

Florida-based medical doctor Rebecca Peck also rejected the proposal, saying that Catholic physicians, patients and religious sisters "should not be told to prescribe or use the Pill under the guise of 'preventative care' or 'good' medicine."

"It simply is not true."

In a Jan. 30 commentary in the Los Angeles Times, Malcom Potts contended that Catholic teaching on the immorality of contraception is based on "misunderstandings and theological errors."

He said that the use of the contraceptive pill has health benefits including a reduced risk of ovarian and uterine cancer and poses "no change" in breast cancer risk.

Potts, an obstetrician, reproductive scientist and professor of public health at the University of California-Berkeley, is also an abortion rights advocate who was the International Planned Parenthood Federation's first director of health.

He suggested that Pope Francis should "reverse" Pope Paul VI's 1968 encyclical on contraception, "Humanae Vitae." Commenting on the Little Sisters of the Poor's resistance to government mandates to provide contraceptives in their health care plan, he said the nuns would reduce their cancer risk by taking contraceptives.

Hilliard countered Potts by citing the National Cancer Institute, the U.S. government's main agency for cancer research. The institute said that the risks of endometrial and ovarian cancer appear to be reduced by oral contraceptives, but the risks of breast, cervical and liver cancer appear to be increased. Breast cancer risk was highest for women who started using oral contraception as teenagers.

Peck, who practices medicine in Ormond Beach and serves as assistant clinical professor at Florida State University's Daytona Beach Regional Campus, said Potts was right to note the reduction in endometrial and ovarian cancers.

However, this is "only a half-truth." These cancers are "relatively rare," she explained, with a 1 in 39 lifetime risk for endometrial cancer and a 1 in 72 lifetime risk of ovarian cancer.

In contrast, breast cancer is the "most common female cancer" with a lifetime risk of 1 in 8.

Proposals to give the birth control pill to religious sisters, who already face a somewhat higher breast cancer risk due to childlessness, would "substantially" increase their breast cancer risk.

While the contraceptive drug can provide relief of symptoms for women with endometriosis, acne and dysmenorrhea, Peck said, all women should receive "informed consent about the many harms of the pill" and about alternative treatments which don't increase risks of cancer or cardiovascular disease.

Potts' L.A. Times essay questioned whether the use of the pill was unnatural, arguing that women have many more menstrual cycles than they did in the past. Women who endure "the hormonal turmoil of hundreds of menstrual cycles" face a health risk, he claimed.

Hilliard, a registered nurse with a master's degree in maternal-child health, objected to Potts' depiction of modern women's hormonal cycles as unnatural.

She called it "interesting" how "Mr. Potts views the beauty of the female reproductive cycle as: placing women in a position of 'enduring the hormonal turmoil of hundreds of menstrual cycles,' as if our feminine nature is violative of us a women, when it is when that nature is exploited, mutilated, and abused that women are violated."

Theologian Angela Franks, who authored the 2013 book "Contraception and Catholicism: What the Church Teaches and Why," said that Paul VI's encyclical correctly recognized that sex is "by its nature oriented to creating new life."

She said the contraceptive pill is "morally problematic" because its use is "treating pregnancy like a disease and the healthy, fertile female body like a sick patient."

Janet Smith, a moral theology professor at Sacred Heart Major Seminary in Detroit, also criticized Potts, saying that the "deleterious effects of contraceptives on the culture look worse and worse the more one knows."

In addition to cancer risks, women who use contraceptives face an increased risk of depression and weight gain, reduced sex drive, and an increased likelihood of choosing incompatible mates. Out-of-wedlock births are also very high despite increased use of contraceptives, Smith added, while the majority of abortions are a result of "failed relationships or relationships made possible by contraception."

Smith noted that several women have died as a result of some newer forms of contraception, citing a January 2014 article in Vanity Fair about Erika Langhart. The 24-year-old woman died suddenly on Thanksgiving Day, 2011 of a massive double pulmonary embolism attributed to an occasional side effect of the NuvaRing contraceptive.

Potts' essay also cited the Pontifical Commission on Birth Control, which had initially advised Paul VI to declare the contraceptive pill morally acceptable.

Franks explained that Vatican commissions are "purely advisory committees" and Popes are "free to accept or reject such advice."

In the case of the Pontifical Birth Control Commission, she said, commission members "created the false picture of themselves as a secondary Magisterium."

Hilliard said that Paul VI issued "Humanae Vitae" after reviewing both the majority and minority reports of the commission and that the majority opinion offered the Pope "incredibly flawed reasoning."    

The commission's majority believed that it is natural to man "to use his skill in order to put under human control what is given by physical nature." According to Hilliard, this is in fact espousing the "chemical mutilation of a normal healthy function of women."

Smith also defended Paul VI's teaching, noting that "Anybody who has been paying attention to what is going on in studies of the effect of contraceptives on women and on society would be grateful that Paul VI rejected the findings of his special commission."

Catholic writer Simcha Fisher – author of 2013's "The Sinner's Guide to NFP" – said that Paul VI's encyclical was prophetic in predicting that widespread contraceptive use would result in greater marital infidelity, male indifference and exploitation of women, and government-imposed contraception as a way of "controlling" people.

"All of these things have come true," she said.