Combined hormonal contraceptives
11 November 2024

- I've been taking birth control pills for a long time, is this bad?
- There is a family history of breast cancer, can I take birth control pills?
- Is there a relationship between birth control pills and cancer?
- I have a lot of pain during my period, can birth control pills help me?
- I have very irregular and heavy periods, are birth control pills an option for me?
- Do I need to take breaks from taking birth control pills?
- Since I started taking birth control pills, I haven't had my period, is this normal?
- What are the routes of administration?
- Do birth control pills make you gain weight?
What do birth control pills contain?
Birth control pills contain estrogen and progesterone, the same hormones that the ovaries secrete each month.
This is the first thing we need to know: every month, due to stimulation from the hypothalamus and the pituitary gland, the ovaries start working, and one of their follicles starts to secrete estrogen until ovulation occurs, from then on, the ovaries also start to produce progesterone. If there is no pregnancy, both hormones decrease, we have our period, and we start again.
On the other hand, contraceptives are made from different versions of estradiol that are extracted from natural sources, such as sweet potatoes or soybeans in a laboratory.
Is there any relationship between contraceptives and cancer?
The WHO classifies contraceptives as class 1 carcinogens. Is this very serious? Let's see:
There are some cancers that are hormone-dependent, such as breast cancer or endometrial cancer, that is, these malignant cells that appear have receptors for estrogens and are stimulated by them. In this sense, the stimulus would be the same, whether this estrogen is produced by the ovary or comes from a contraceptive. Any estrogen could stimulate these cells, not only those manufactured in a laboratory, what happens is that the WHO does not classify hormones of ovarian origin as carcinogenic. For example, estrogens produced during pregnancy increase the risk of breast cancer by 5% and do not decrease to baseline values until 5 years later.
The risks and benefits of each treatment must be discussed individually with each patient, since each one is unique in their background, family history and motivation for taking or not taking contraceptives. The WHO has guidelines for evaluating risks, which can be consulted on the WHO website.
The WHO continues to recommend the use of contraceptives, so it is clear that it is not considered a carcinogenic risk factor similar to tobacco, for example.
What do studies say about the association of combined contraceptives with cancer?
Risk of breast cancer.
There are some studies that evaluate the relationship between combined contraceptives and breast cancer, showing an increase in risk in women while taking the pill that varies from 8-24% depending on the study. It seems like a lot, but, taking into account that the baseline risk is very low, the risk is very low: taking the highest percentage, this would mean that, for every 7,960 women who take contraceptives, there would be one extra case of breast cancer per year. In women under 35 years of age, this would imply 1 more case for every 50,000 women who take combined contraceptives.
In the study published in 2021 by Karlson et al, it is concluded that the increase in cancer risk with the use of combined contraceptives is very low, lower than the increase in risk associated with pregnancy
Endometrial cancer and ovarian cancer
Contraceptives reduce the risk of endometrial and ovarian cancer. In women who took combined contraceptives for more than 20 years, there was a 60% reduction in the risk of endometrial cancer and a 40% reduction in ovarian cancer. This reduction in risk is maintained 30-35 years after discontinuing use.
This protective effect is due to the presence of progesterone in contraceptives, which counteracts the effect of estrogen.
What are the benefits of contraceptives?
- They prevent pregnancy, a significant benefit, since an unwanted pregnancy affects many areas of health, both mental and physical. The number of abortions is reduced. In developing countries, birth control through the use of contraceptives is a factor related to the degree of autonomy of women.
- They reduce the volume of bleeding, thus managing to reverse iron deficiency anemia.
- They reduce pain during menstruation, dysmenorrhea.
- They reduce diarrhea associated with menstruation.
- They reduce pain associated with endometriosis and its progression.
- They improve premenstrual syndrome.
- They improve acne and hirsutism (excess hair).
- They have a protective effect on bone mineral density in adolescents or adults with hypoestrogenism (amenorrhea or lack of menstruation secondary to anorexia, for example).
What other risks can be involved in taking contraceptives?
They increase the risk of thrombosis. Estrogens, in particular, have a procoagulant effect, which is dose-dependent. This means that they encourage blood to form clots. In patients with risk factors: obesity, personal or family history of venous thrombosis, their use should be avoided. Contraceptives with a lower dose of ethylinestradiol equalize the risk of arterial thrombosis to that of the general population, although the risk of peripheral venous thrombosis persists. In pills containing low doses of ethylinestradiol, the risk of deep vein thrombosis depends on the progestogen they contain:
- There is a risk of hypertension induced by combined contraceptives. It is a rare event
- Acute myocardial infarction or stroke: only in the case of patients with hypertension and smoking, in which case, their use should be avoided.
- Hepatic adenoma. Estrogens can stimulate the growth of this type of benign tumor. Patients with a family or personal history of adenoma should not take them.
- Patients who have migraines, especially if they have aura, usually experience worsening of their symptoms with the use of contraceptives
What administration routes are there?
Combined contraceptives can be administered by different routes:
Oral: in the form of contraceptive pills. They are sold in different dosage forms: 21 tablets, 28 tablets, 24+4 tablets. This refers to the number of pills in the box and the number of pills without hormonal content, but with the idea of making use easier by making forgetting difficult.
Vaginal: in the form of a hormone-releasing ring that is inserted into the vagina
Transdermal: in the form of transdermal patches
What happens with bleeding when you take contraceptives?
In general, the use of combined contraceptives (which contain estrogen and progesterone) makes the amount of bleeding during menstruation much less, improving pain. In addition, it is an orderly cyclic bleeding.
However, during the first 3 months of use, a small intracyclic bleeding may occur. This bleeding between periods usually disappears after the first three months of use and occurs mainly because the estrogen dose is low and sufficiently controls the proliferation of the endometrium. If it persists beyond that, you should be checked/consulted again, have an ultrasound done to rule out other causes of bleeding, change to another preparation with a higher dose or change the administration route.
Another thing that can happen in 2% of patients in the first year is not having bleeding, that is, there are some women who do not have a period while taking contraceptives. This does not reduce the effectiveness of the contraceptive, and it is due to the fact that the dose of estrogen is insufficient to make the endometrium proliferate, or because the effect of the progestogen predominates. If this causes anxiety in the patient, she could change to another contraceptive with a higher dose, rest a cycle or change the method.
Do contraceptives cause weight gain?
Despite being one of the most feared side effects, especially among younger women, the studies carried out do not find a relationship between weight gain and the use of combined contraceptives.
Bibliography:
- WHO Medical eligibility criteria for contraceptive use. Fourth edition. Department of Reproductive Health, World Health Organization.
- Lina S. Mørch et al. Contemporary Hormonal Contraception and the Risk of Breast Cancer. N Engl J Med 2017; 377:2228-2239.
- Nicholas HB et al. Breast Cancer Risk After Recent Childbirth. A Pooled Analysis of 15 Prospective Studies. Annals of Internal Medicine. 2019;170:22-30.
- ACOG Hormonal Contraception and Risk of Breast CancerPractice Advisory. January 2018.
- PubChem Ethinyl Estradiol https://pubchem.ncbi.nlm.nih.gov/compound/Ethinylestradiol
- Carcinogenicity of combined hormonal contraceptives and combined menopausal treatment, 2005 statement WHO.
- Torgny Karlsson, Therese Johansson, Julia Höglund, Weronica E. Ek, Åsa Johansson; Time-Dependent Effects of Oral Contraceptive Use on Breast, Ovarian, and Endometrial Cancers. Cancer Res 15 February 2021; 81 (4): 1153–1162. https://doi.org/10.1158/0008-5472.CAN-20-2476
- https://www.aemps.gob.es/informa/notasinformativas/medicamentosusohumano-3/seguridad-1/ciudadanos/2013/ni-muh_fv_28-2013-anticonceptivos/
- Contracepción en la adolescencia. Documento SEGO. 2013
- European Medicines Agency 22/11/2013. http://www.ema.europa.eu
- https://www.who.int/es/health-topics/contraception#tab=tab_1
- https://www.aemps.gob.es/informa/notasinformativas/medicamentosusohumano-3/seguridad-1/ciudadanos/2013/ni-muh_fv_28-2013-anticonceptivos/#
- https://sego.es/documentos/ponencias/cursos/141/5.%20Reyes%20de%20la%20Cuesta%20Benjumea%20-%20Asesoramiento%20anticonceptivo%20y%20manejo%20clínico.pdf