Significant Risks of Oral Contraceptives (OCPs) Why This Drug Class Should Not Be Included in a Preventive Care Mandate Rebecca Peck, M.D., C.C.D., and Charles W. Norris, M.D.* Dr. Rebecca Peck is a board-certified family physician, certified clinicaldensitometer, and Marquette Method NFP teacher. Dr. Peck may becontacted at rbamer2@yahoo.com. Dr. Norris is a retired obstetrician/gynecologist and a graduate of the Georgetown University School ofMedicine, class of 1957. He may be contacted at chazno@comcast.net.Abstract Pregnancy is not a disease. But more fundamentally, neither ishuman fertility. They are normal physiologic processes of the sexu-ally mature person. By classifying pregnancy and fertility asdisease states, certain entities are able to position contraceptionas “the cure.” Currently, these same organizations want to includeoral contraceptive counseling and medications in the new nationalhealth-care plan under a preventive care mandate. But it is thephysician’s role to counsel patients on preventive care measures.We understand that these evidenced-based screenings help tochange risky behaviors and catch disease in its earliest stages,thereby reducing patients’ overall morbidity and mortality. How-ever, we believe that patients incur substantial health risks when
* Grateful acknowledgement to Benjamin Peck, M.D., Chris Kahlenborn, M.D.,
The Linacre Quarterly 79(1) (February 2012): 41–56.
2012 by the Catholic Medical Association. All rights reserved.
0024-3639/2012/7901-0006 $.30/page. February 2012Significant Risks of Oral Contraceptiveschoosing oral contraceptives (OCPs). This paper reviews the majorrisks of OCPs. The authors presume that the prevailing widespreadacceptance and promotion of OCPs indicates general agreementwithin the medical community that OCPs are good for the patient(or at least not significantly harmful). Therefore, this paper concen-trates on the studies which show increased harm and risk to thepatient choosing to use OCPs. We have concentrated our efforts onthree major areas: increased rates of cardiovascular disease, breastcancer, and human papillomavirus (HPV) or cervical cancer. If fer-tility and pregnancy are not disease states, and are, in fact, normalconditions associated with healthy individuals, OCPs fail the most
important test of preventive medicine: they increase risk of disease
instead of decreasing it. Patients should not be misled or confusedinto believing that what they are taking is “good for them” and is ofthe same beneficial effect as other preventive measures.Introduction
Primary care physicians spend a substantial part of their clinical
time counseling patients on preventive care. Some examples of these
items include: providing information on diet and exercise; giving smok-
ing cessation counseling; performing diabetes and cholesterol screen-
ings; obtaining mammograms, Pap smears, and bone densitometry; and
administering immunizations. The rationale behind such preventive
screenings is to reduce morbidity and mortality by changing risky behav-
iors and by catching disease in its earliest stages.
Currently, there are several entities that want to include oral con-
traceptive counseling and medications within a preventive care platform.
This proposal is ill-advised for several reasons. Firstly, oral contracep-
tives (OCPs) have their own significant risks, namely, an increase in car-
diovascular events (such as an increase in venous thromboembolism,
pulmonary embolism, myocardial infarction, and stroke) especially in
older women and smokers.1 Secondly, OCPs increase the risk of the
world’s most frequently occurring cancer, breast cancer.2 Thirdly, OCP
use leads to an increase in human papillomavirus (HPV) infection and
an increase in cervical cancer, which is the second most common cancer
worldwide.3 Therefore, OCPs fail the most important test of preventive
medicine: they increase the risk of disease instead of decreasing it.
Pregnancy is not a disease. But more fundamentally neither is
human fertility. Rather, our fertility is a completely normal part of the
physiology of the sexually mature person and is the only normal physio-
logic function medical providers treat as if it were a disease by chemical
suppression, manipulation, or surgical elimination. If, for example, a
physician were to suggest to a woman that he should treat her cardio-
vascular, respiratory, or even her neurologic functioning as he seems
perfectly willing to treat her fertility—mind you, a perfectly normal phys-
iologic process—she would not walk, but run out of his office! Further-42
more, as one of the functions of oral contraceptives is to suppress ovula-
tion and, therefore, a woman’s fertility, is it advisable or even reason-
able for physicians to prescribe a “medication“ which, as its function,
suppresses a perfectly normal physiologic process? We believe not.
This paper will focus on the medical harm caused by OCPs. Since
the birth control pill is so widely prescribed, we do not focus on those
research studies which support its use. Instead, we analyze the current
research available, which shows increased morbidity and mortality in
three key areas: 1) increased cardiovascular events, 2) increased breast
cancer rates, and 3) increased HPV and cervical cancer rates. This paper
will not explore the various side effects of “the Pill,” such as depression,
migraine headache, and weight gain, although these very real concerns
may be one of the reasons why the number of women continuing use of
OCPs is only 68 percent at the end of the first year of use.4 There are also
other serious risks of OCPs, such as an increase in liver tumors, espe-
cially in women with concomitant hepatitis infection, which will not be
Increased Cardiovascular Morbidity and Mortality
Cardiovascular morbidity and mortality first reported in OCP users
were related to the ethinylestradiol content. Since the 1960s when “the
Pill” was introduced, the estrogen dose has been continually reduced. As
different progesterone compounds were used, cardiovascular risks have
been correlated with lipid profile changes. Progestins with androgenic
properties, for example, have been partially responsible for these cardio-
vascular events reported in OCP users. In order to minimize the inci-
dence of adverse drug reactions and to induce beneficial changes in lipid
patterns, new progestational molecules devoid of androgenic properties
have been recently synthesized. These compounds are the so-called
“third-generation” progestins and were thought to have lower cardiovas-
cular risks when they first came out.6 Unfortunately, this has not been
the case, as there are some well-known class action lawsuits against phar-
maceutical companies making such OCPs known as Yaz and Yasmin.
The incidence of venous thromboembolism (VTE) among healthy
women is low but increases with age.7 Oral contraceptives are associated
with a three to five times higher risk of VTE.8 The risk appears to be pro-
portional to the estrogen dose and the type of progestin used. According
to a recent Danish study, over two thousand women were studied for six
years (10.4 million woman years were recorded), with the research
focused on the venous thrombotic events per type of progestin used.
Compared with OCPs containing levonorgestrel and with the same dose
of estrogen and length of use, the rate ratio for OCPs with norethisterone
was 0.98, with norgestimate 1.19, with desogestrel 1.82, with gestodene
1.86, with drospirenone 1.64, and with cyproterone 1.88. They con-
cluded that for the same dose of estrogen and the same length of use, theFebruary 2012Significant Risks of Oral Contraceptives
new generation OCPs using desogestrel, gestodene, or drospirenone
were associated with a significantly higher risk of venous thrombosis
than the older generation OCPs using levonorgestrel. In a separate study
published in The Lancet, researchers determined that the excess risk for
nonfatal VTEs linked to this new generation of OCPs to be 16/100,000
woman years. In contrast, the older generation OCPs had rates of around
4.3/100,000 woman years. In fact, as of September of 2011, the FDA was
still “concerned about the potential increased risk of blood clots with the
use of drospirenone-containing birth control pills.”9 The FDA has com-
pleted a review of two 2011 studies that found a two to three times
greater risk of VTEs for women who use birth control and held a meet-
ing December 8, 2011, to discuss the risks and benefits of OCPs that
contain drospirenone.10 And a few years previously on January 18, 2008,
the FDA updated the label on the Ortho Evra Patch to reflect the Boston
Collaborative Drug Surveillance Program data which showed that
women on the patch had higher risk for VTE.11
Pulmonary embolism risks are also higher in patients that use
OCPs. This is, in fact, because VTE and pulmonary embolisms are sim-
ilar phenomena, whereby clots can break off from the existing clot in
the leg (which is defined as a VTE) and subsequently travel to and
become lodged in the lungs. As stated above, pulmonary embolism is
related to the estrogen dose and the type of progestin. A Lancet study
noted that OCPs containing desogestrel or gestodene are associated
with higher risks of fatal pulmonary embolisms than are those contain-
ing levonorgestrel. This is consistent with most previous studies com-
paring the effects of second-generation progestins on VTE.12 As an
aside, the Ortho Evra patch is another form of hormone delivered by
transdermal application and has been associated with increased rates
of pulmonary embolism. This patch has also made the headlines lately.
The presumed mechanism is that the patch delivers a higher dose of
estrogen into the circulatory system by avoiding the “first-pass” metab-
The risk of VTE associated with hereditary thrombophilias (such
as Factor V Leiden mutation, hereditary deficiencies of antithrombin III,
protein C, protein S, plasmingoen, factor XII and dysfibrinogenemia) is
further increased with OCP use. The risk of VTE in women who have
Factor V Leiden and use OCPs is thirty-five times higher than women
who do not have the mutation and who do not use OCPs. Factor V Lei-
den and some of these other hereditary deficiencies are like “ticking time
bombs.” The women may not know that they carry the mutation until
they take OCPs. Due to the extreme cost of screening for these muta-
tions, it would not be feasible in a cost-restricted health-care environ-
ment to screen every patient for this mutation. Currently, when a VTE
occurs in a patient using OCPs, the recommended blood tests for hered-
itary thrombophilias is carried out. Physicians should perform a detailed
family history on every patient presenting for OCPs; and if there is a his-44
tory of multiple family members with VTE, such hereditary conditions
should be suspected. Unfortunately, in the current rushed health-care
environment, complete family histories (and informed consent) are
The risk of myocardial infarction is extremely rare among repro-
ductive-aged women. Use of low dose OCPs increases the risk of myocar-
dial infarction by 200 percent. However the risk of myocardial infarction
in OCP users who smoke (under age thirty-five) is increased tenfold over
that of nonsmokers who take OCPs. For women over the age of thirty-
five who smoke, the increase of risk is even higher.14 According to the
Oxford Family Planning Association study, oral contraceptive use in
smokers increased the risk of fatal ischemic heart disease.15 According
to the WHO Collaborative Study of Cardiovascular Disease and Steroid
Hormone Contraception, current use of OCPs is associated with an
increased risk of myocardial infarction among women with known car-
diovascular risk factors and among those who have not been effectively
screened, particularly for blood pressure.16 Older women who smoke
have excess risk associated with OCPs (400/100,000 woman-years).
Another study showed that hypertensive OCP users were at higher risk
for stroke and myocardial infarction than hypertensive non-OCP users.17
The risk of idiopathic cardiovascular death for women using OCPs
was examined by researchers using two separate studies analyzed from
the U.K. General Practice Research Database. They found that there
were fifteen unexpected idiopathic cardiovascular deaths in the follow-
ing proportions: 4.3/100,000 for levonorgestrel OCPs, 1.5/100,000 for
desogestrel OCPs, and 4.8/100,000 for gestodene OCPs.18
The risk of stroke in young women is rare, but substantially
increased in users of OCPs. Risk is associated with higher estrogen doses,
advanced age, and smoking. The risk of stroke in women with migraines
who use OCPs is also increased significantly by smoking.19 The risk of
hemorrhagic stroke in women thirty-five years and older who smoke and
are taking OCPs was 2.2 times higher than non-users.20 The estimated
risk of stroke with higher-estrogen dose OCPs was associated with an
Increased Breast Cancer Risk
According to the National Cancer Institute Surveillance Epidemi-
ology and End Results, breast cancer is the most common female can-
cer in the U.S. and worldwide. According to rates obtained from 2005
to 2007, the lifetime risk that a woman will develop breast cancer is
12.15 percent (or 1 in 8 women). Another way to look at the data is to
say that 122.9/100,000 women will develop breast cancer per year
Cervical cancer prevalence varies depending upon where the
patient lives. For example, in Eastern Africa, cervical cancer is the leadingFebruary 2012Significant Risks of Oral Contraceptives
cause of death from cancer, while in developed countries, the rates are
lower. Worldwide, the International Agency for Research on Cancer
(IARC) estimates that 15.3/100,000 women will develop cervical can-
cer worldwide per year. In Africa, the rate increases to 25.2/100,000
women.23 According to the SEER data, in the U.S., 8.1/100,000 women
will develop cervical cancer. For blacks, this rate increases to 10.1/
100,000 women and for Hispanics, 12.0/100,000 women.24
A recently published study analyzed global breast and cervical can-
cer rates from 187 countries over the period from 1980 to 2010. Results
showed that the global breast cancer incidence increased from 641,000
cases in 1980 to 1.64 million cases per year during 2010, an annual rate
of increase of 3.1 percent. The global incidence of cervical cancer also
increased during the study period, from 378,000 to 454,000 cases per
year, an annual rate of increase of 0.6 percent. The authors conclude
that in developing countries in the reproductive age groups, breast and
cervical cancer are significant problems of a similar importance to major
global priorities such as maternal mortality.25 One should ask why breast
and cervical cancers are rising so rapidly. It is interesting to note that
contraceptive use has increased worldwide overall during this period but
substantially over the decade from 1995 to 2005 in the less developed
Uterine and ovarian cancers occur at higher rates in the U.S. than
they do worldwide, but they still lag way behind breast cancer, which is
by far, the most frequently occurring cancer in the U.S. and worldwide.
The incidence of uterine cancer is 23.5/100,000 women. The lifetime
risk of developing uterine cancer is 2.58 percent (or 1 in 39 women).27
Ovarian cancer incident rates are 12.8/100,000 women. The lifetime
risk of developing ovarian cancer is 1.39 percent (or 1 in 72).28
Why are these rates important? Because many studies promoting
the benefits of OCPs in the literature tout lowered risks of uterine and
ovarian cancers, yet minimize the increase in risk of breast and cervical
cancers caused by these same OCPs. Since the incident rate of breast
cancer is six times higher than that of both uterine and ovarian cancers,
it is important to highlight this point.29 Even small increases in the rela-
tive risk (RR) of breast cancer caused by OCPs translate into much larger
increases in absolute risk of breast cancer.
In 1972, a series of animal research studies showed that an oral
contraceptive appeared to cause metastatic breast cancer in monkeys,
which rarely develop breast cancer.30 A study in 1981 found that women
who took OCPs for four years prior to their first full-term pregnancy
(FFTP) had a 125 percent increased risk of breast cancer before age
thirty-two.31 In 1993, the Cancer and Steroid Hormone study (CASH)
showed a 40 percent increased relative risk in women taking OCPs
before their first full-term pregnancy.32 Dr. Chris Kahlenborn’s meta-
analysis in Mayo Clinic Proceedings analyzed thirty-four case-control
studies of OCPs and premenopausal breast cancer and found that the46
use of OCPs was associated with an increased risk of premenopausal
breast cancer in general (odds ratio 1.19), but when OCPs were used
before FFTP, the risk went up to 1.44.33 The association between OCP
use and breast cancer risk was greatest for women who had used OCPS
for more than four years (odds ratio 1.52).34
In a very recent study at Harvard, 116,608 patients were enrolled
in a prospective cohort study which found that current use of OCPs
carries an excess risk of breast cancer with levonorgestrel accounting
for much of the risk.35 Another population-based case control study
examined the relationship between use of OCPs and breast cancer;
and among women in a cohort younger than forty-five years old, they
found that OCP use for six months or longer was associated with a rel-
ative risk of 1.3 with the RR rising to 2.2 for users of ten or more
years.36 In another case control study (the Case Control Surveillance
Study), the relative risk of breast cancer for OCP use over one year or
more was 1.5. The famous “triple-negative breast cancer (TNBC)”
study which came out in 2009 showed that OCP use greater than one
year was associated with a 2.5-fold increased risk of triple-negative
breast cancer. Among women younger than forty years of age, the RR
of triple-negative breast cancer associated with OCP use greater than
The largest meta-analysis, comprised of fifty-four epidemiologi-
cal studies (Collaborative Group on Hormonal Factors in Breast Can-
cer), included 53,297 women with breast cancer and 100,239 controls.
Women who were currently using OCPs had an increased RR of breast
cancer (RR 1.24); and women who had used OCPs before the age of
twenty had an elevated risk for breast cancer over subsequent years
The Black Women’s Health Study from 1995 to 2007 results indi-
cated that OCPs increased the RR to 1.65 with a greater effect for estro-
gen negative than estrogen positive cancer.39 Another retrospective case
control of African American women showed that OCPs also conferred a
significantly increased risk of breast cancer.40
Regarding the risk of breast cancer based upon the hormonal con-
tent, a U.S.-based case-control study evaluated rates of breast cancer
and estrogen and progesterone formulations. They found that women
who recently used OCPs containing more than 35 mcg of ethinylestra-
diol were at higher risk than users of lower dose preparations (RR ϭ 1.99
and 1.27 respectively). They also found that this relationship was more
marked among women younger than thirty-five years of age. They also
found significant trends of increasing breast cancer risk for pills with
higher progestin and estrogen potencies.41
There are several studies which show an increased rate of breast
cancer for women who have used both OCPs as younger women and then
are re-exposed as older women when they take hormone replacementFebruary 2012Significant Risks of Oral Contraceptives
therapy (HRT). The RR increases to 2.77 for women who use both
There are now several randomized control trials that show the use
of HRT increases the risk of breast cancer for postmenopausal women.43
An important point to note is that the compounds that comprise HRT
(estrogen and progesterone derivatives) are similar to compounds found
in OCPs. The HRT data showed an increase in postmenopausal breast
cancer after just five years of use. Young women, with susceptible breast
tissue (those who have not had their first full term pregnancy yet), are
exposed to stronger estrogen and progesterone derivatives for much
longer periods of time. All of the case control studies cited in this paper
showed an increased relative risk of breast cancer in younger women
who used OCPs before their first full-term pregnancy, and for those that
It is normal for physicians to warn their postmenopausal patients
of the risks when discussing HRT. Why are we, the medical community,
warning older women of the risks of HRT but not cautioning the younger
women about these hormones? Some young women start OCPs right
after menarche, while their breast tissue is highly susceptible to the
effects of carcinogens.44 The International Agency for Research on
Cancer classified estrogen and progesterone as Class I carcinogens
in 2005.45 According to Angela Lanfranchi, M.D., breast surgeon, the
breast goes through a series of phases whereby tissue matures and devel-
ops. It is not until the woman has reached at least 32 weeks of her first
pregnancy, that those breast cells become fully matured. After the breast
cells have matured to this level, they are “protected” to some extent
against carcinogenic influences. Therefore, exposing young women’s
breasts to years of carcinogenic hormones, before they have their babies,
This important issue will need to be clarified with randomized con-
trolled trials. Why have no randomized controlled trials been performed
to date? One reason may be that it would not be in the best interest of
the pharmaceutical industry to perform such expensive studies, espe-
cially if we examine what happened with the HRT experience. Up until
2002, physicians mistakenly recommended HRT to postmenopausal
women for cardiovascular health benefits and cancer protection. Once
the results of the Women’s Health Initiative were publicized in the main-
stream media, prescriptions for HRT dropped by half in just a couple of
months. There are currently over one hundred million prescriptions for
OCPs filled worldwide. In light of the revelations from the Women’s
Health Initiative, the impact of the fallout of studies of OCPs and breast
Finally, there are several problems with the existing cohort studies
which show that OCPs are not harmful and are not associated with
increased risks of breast cancer. Dr. Chris Kahlenborn and others have
documented several problems with statistical tools like “person-years”48
and the use of cohorts of women who were not exposed to OCPs as young
women before their first full-term pregnancy.47 Dr. J. Brind found, in his
analysis of the RCGP oral contraception study, that the widely touted
12 percent reduction in the risk of any cancer was largely an artifact
resulting from a biased exclusion criteria. When he analyzed the data, he
found that there was an increase in breast cancer risk, peaking between
fifteen and twenty years after cessation of use instead of disappearing ten
years after cessation of use, as others have reported.48 These findings
underscore the need for reanalyzing the OCP/breast cancer research. Increased Rates of Human Papillomavirus (HPV) and Cervical Cancer
The use of OCPs has been associated with an increased risk of cer-
vical intra-epithelial neoplasia (CIN) and cervical cancer.49 OCPs most
likely act as a co-factor in the development of this disease. Oral contra-
ceptives are classified by the International Agency for Research on Can-
cer as a cause of cervical cancer.50 There are many possible reasons why
OCPs increase the rates of cervical cancer. Although HPV appears to be
the strongest factor in the causation of the disease, not all women with
HPV develop cervical cancer. Oral contraceptives have been postulated
to be one mechanism whereby HPV exerts its oncogenic effect on cervi-
cal tissue. The OCPs may bind to HPV DNA to either increase or sup-
press transcription of certain genes.51 Other studies show that OCPs (and
other factors such as smoking) may accelerate the cervical maturation
process, representing increased cell proliferation and thus a possible
greater vulnerability to HPV.52 Still other studies show that long-term
use of OCPs may lead to a more frequent persistence of HPV.53
In a 2007 meta-analysis that appeared in The Lancet, 16,473
women with cervical cancer and 35,509 without cervical cancer were
reanalyzed centrally. The relative risk of cervical cancer is increased in
current users of OCPs and declines after cessation. Ten years of using
OCPs from around age twenty to thirty years is estimated to increase the
cumulative incidence of invasive cervical cancer by age fifty from
7.3/1,000 to 8.3/1,000 in less developed countries and from 3.8/1,000 to
4.5/1,000 in more developed countries.54 Another earlier meta-analysis
showed that long duration use of OCPs is associated with an increased
risk of cervical cancer also.55 Still, another large prospective cohort study
of 47,000 women showed that those who had used OCPs had a signifi-
cantly higher rate of cervical cancer than never-users.56
A population-based cohort study of over 10,000 women showed
positive correlation of HPV prevalence with older age and current use of
OCPs. This study occurred in South Africa where cervical cancer rates
Data from a hospital-based case-control study collected between
1979 and 1988 in ten participating hospitals in eight countries wereFebruary 2012Significant Risks of Oral Contraceptives
analyzed to determine whether OCPs alter the risk of cervical cancer.
Risk increased with duration of OCP use, was highest in recent and cur-
rent users, and declined with time since cessation of use.58 Other studies
confirmed that the risk of HPV infection was strongly and independently
associated with increasing numbers of sexual partners in a lifetime, use
The Preventive Care Mandate
The new government contraceptive mandate requires that we, as
physicians: 1) treat a normal physiologic function, fertility, as if it were a
disease; 2) consider OCPs as preventive medicine; and 3) as we have
demonstrated, violate our Hippocratic Oath to “do no harm.”
Regarding the premise that fertility is not a disease, we have a sci-
entific culture that has always compared the risks of contraception to
the risks associated with pregnancy. Why has this convention been so
successfully used? Shouldn’t the risks of contraceptives be compared to
the non-pregnant state? In other words, when we evaluate the risk of
VTEs with OCPs, for example, why is this compared to the risk of VTE
during pregnancy instead of during the non-pregnant state? Is it because
the problems associated with OCPs will then appear smaller than they
otherwise would? And, is it also because pregnancy and fertility have
successfully been positioned as disease states rather than natural phases
in the reproductive cycle of a human being? Perhaps a more appropriate
comparison would be between OCPs and modern methods of delaying
pregnancy (such as natural family planning).
If the goal of a government is to prevent pregnancy, as it is in
China, for example, then contraceptive counseling is preventive medi-
cine. But in the U.S., fertility seems to be defined by physicians as a
“disease” if the woman does not want to become pregnant and the
“cure” if she has been struggling with infertility and is finally able to
achieve pregnancy. How can fertility be simultaneously disease and
cure? If the physician offered contraceptive counseling to an infertile
woman struggling to achieve pregnancy, this would be considered
strange medicine indeed,— almost a form of harassment from the poor
woman’s standpoint. But shouldn’t preventive medicine standards
And what about the physicians’ oath to do no harm? In addition to
all the real harms of OCPs presented in this paper, are we really going to
discuss all of the other risks of premarital sex with our patients, such as
the very real risk of contracting various sexually transmitted diseases
(STDs) with their use of those same OCPs? Are we going to discuss the
role of premature sex and acquisition of HPV leading to cervical cancer?
Are we going to discuss the use of condoms along with the OCPs? How
about the risk of condom rupture with condom use? Even if physicians
feel ethically that they cannot “impose” their Catholic morality upon50
their patients, they can rightly insist that their patients be given ade-
quate and complete informed consent about all of the risks of oral con-
traceptives. More importantly, they can certainly take the opportunity
to educate their patients on abstinence and NFP (natural family plan-
ning). There are no harmful risks or side effects from the use of absti-
Conclusion
Preventive medicine is the backbone of any medical system.
Patients must have confidence that the measures physicians are recom-
mending are going to be beneficial for their health. Oral contraceptives
increase rates of cardiovascular morbidity and mortality, as well as
increasing the rates of breast and cervical cancers. Patients need com-
plete informed consent on all of the possible risks of OCPs. Complete per-
sonal and family histories need to be ascertained by health-care providers
to ensure that adverse events do not occur. Patients do incur health risks
when choosing oral contraceptives. They should not be misled or con-
fused into believing that what they are taking is “good for them” and has
similar beneficial effects to other evidence-based preventive measures.
1 See notes 8, 12, 15, 16, 17, 18 below. And see V. Cogliano et al., “Carcinogenic-
ity of Combined Oestrogen-Progestagen Contraceptives and Menopausal Treat-
ment,” IARC Monograph Working Group, Lancet Oncology 6 (2005): 552– 554;
A. Blanco-Molina and M. Monreal, “Venous Thromboembolism in Women Tak-
ing Hormonal Contraceptives,” Expert Review of Cardiovascular Therapy 8
(2010): 211– 215; O. Lidegaard et al., Hormonal Contraception and Risk of
Venous Thromboembolism: National Follow-up Study, British Medical Journal
339 (2009): b2890; K.M. Curtis et al., “Contraception for Women in Selected
Circumstances,” Obstetrics and Gynecology 99 (2002): 1100– 1112; H. Jick
et al., “Risk of Idioipathic Cardiovascular Death and Nonfatal Venous Throm-
boembolism in Women Using Oral Contraceptives with Differing Progestagen
Components,” Lancet 346 (1995): 1589– 1593. 2 See notes 5, 32, 33, 34, 35, 36, 37, 38, 40, 41, 42, 48 below. And see Cogliano
et al., “Carcinogenicity of Combined Oestrogen-Progestagen Contraceptives and
Menopausal Treatment”; Practice Committee of the American Society for Repro-
ductive Medicine, “Hormonal Contraception: Recent Advances and Controver-
sies,” Fertility and Sterility 82 (2004): 520– 526; E. White et al., “Breast Cancer
Among Young U.S. Women in Relation to Oral Contraceptive Use,” Journal ofthe National Cancer Institute 86 (1994): 505– 514; L. Rosenberg et al., “A Case-
Control Study of Oral Contraceptive Use and Incident Breast Cancer,” AmericanJournal of Epidemiology 169 (2009): 473– 479; C. Sweeney et al., “Oral, Injected
and Implanted Contraceptives and Breast Cancer Risk Among U.S. Hispanic and
Non-Hispanic White Women,” International Journal of Cancer 121 (2007):
2517– 2523; R. Ghiasvand et al., “Risk Factors for Breast Cancer Among YoungFebruary 2012Significant Risks of Oral Contraceptives
Women in Southern Iran,” International Journal of Cancer 129 (2011): 1443–
1449; L. Rosenberg et al., “Oral Contraceptive Use and Estrogen/Progesterone
Receptor-Negative Breast Cancer Among African American Women,” CancerEpidemiology, Biomarkers and Prevention 19 (2010): 2073– 2079; H. Lyytinen
et al., “Do the Dose or Route of Administration of Norethisterone Acetate as a
Part of Hormone Therapy Play a Role in Risk of Breast Cancer: National-Wide
Case-Control Study from Finland,” International Journal of Cancer 127 (2010):
185– 189; J.J. Schlesselman, “Cancer of the Breast and Reproductive Tract in
Relation to Use of Oral Contraceptives,” Contraception 40 (1989): 1– 38; J.H.
Johnson, “Weighing the Evidence on the Pill and Breast Cancer,” Family Plan-ning Perspectives 21 (1989): 89– 92; L. Rushton and D.R. Jones, “Oral Contra-
ceptive Use and Breast Cancer Risk: A Meta-analysis of Variations with Age at
Diagnosis, Parity and Total Duration of Oral Contraceptive Use,” British Journalof Obstetrics and Gynecology 99 (1992): 239– 246; I. Romieu, J.A. Berlin, and
G. Colditz, “Oral Contraceptives and Breast Cancer. Review and Meta-analysis,”
Cancer 66 (1990): 2253– 2263; E. Lund et al., “Hormone Replacement Therapy
and Breast Cancer in Former Users of Oral Contraceptives: The Norwegian
Women and Cancer Study,” International Journal of Cancer 121 (2007): 645–
648; M.A. Rookus and F.E. van Leeuwen, “Oral Contraceptives and Risk of
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Communications Office, Banyu Pharmaceutical Co., Ltd., Public Relations, Ono Pharmaceutical Co., Ltd. New Data Released at ADA Showed that Initial Combination Therapy with sitagliptin and Metformin Led to Significant Improvement in Markers of Beta Cell Function in Patients with Type 2 Diabetes (Second Report) Merck & Co., Inc, Whitehouse Station, New Jersey, U.S.A. presented
Ley Nº 16.107 (del 31 de marzo de 1990) Banco de Previsión Social Dispónese Ajuste Fiscal Tributario y de aportación Artículo 1 Sustitúyese el literal A) del Título 10 del Texto Ordenado de 1987, por el siguiente: "A) Básica del 22% (veintidós por ciento)" El aumento de la tasa dispuesto por la presente disposición, tendrá vigencia a partir del primer d