Natural Family Planning (NFP) methods are suitable for all women, including:

• girls and very young women with irregular cycles,
• women of various ages who are planning a pregnancy or experiencing difficulty conceiving,
• women who wish to postpone childbearing and identify their fertile and infertile days,
• postpartum and breastfeeding women,
• women in perimenopause, when menstrual cycles often become irregular,
• and women who want to monitor their fertility for diagnostic or health‑related purposes.

There are no contraindications to using Natural Family Planning (NFP) methods at any age or in the presence of illness or chronic health conditions.

By contrast, contraceptive methods are generally intended for otherwise healthy women. Manufacturers list numerous limitations and contraindications, including the following:

• Combined oral contraceptive pills are contraindicated in cases of a family history of vascular disease, ischemic heart disease, heart valve disorders, hypertension, varicose veins, blood clotting disorders, familial hyperlipidemia, diabetes, liver disease, a history of pregnancy-related jaundice or trophoblastic disease, migraines, and breast or uterine cancer.
• Progestin-only pills carry similar contraindications, including cardiovascular disease in the family, ischemic heart disease, heart valve defects, hypertension, varicose veins, clotting disorders, hyperlipidemia, diabetes, liver disease, previous pregnancy-related jaundice or trophoblastic disease, migraines, and breast or uterine cancer.
• Contraceptive patches are not recommended for individuals with liver disease, a family history of cardiovascular disorders, circulatory system diseases, hypertension, prolonged immobility, smoking, severe obesity, anemia, or lupus.
• Intrauterine devices (IUDs) are contraindicated in cases of recurrent pelvic infections, anemia, unexplained irregular bleeding, suspected pregnancy, a history of ectopic pregnancy, congenital or structural abnormalities of the uterus, uterine fibroids or cysts, allergies to IUD components, as well as in women who have not given birth or who have compromised immune systems.

It is also important to remember that hormonal contraceptives should not be used to “treat” irregular menstrual cycles. These methods suppress the natural hormonal rhythm and impose an artificial cycle. The bleeding that occurs during pill-free intervals is not true menstruation but rather a withdrawal bleed caused by the sudden absence of progestins (synthetic progesterone analogues). After discontinuing hormonal contraception, the body often requires time to restore its natural hormonal balance.

The composition of hormonal contraceptives is designed to mimic the second (postovulatory) phase of a woman’s menstrual cycle – a phase characterized by a Pearl Index of 0, indicating natural infertility.

Hormonal contraception works primarily by suppressing ovulation or disrupting normal follicular development, altering the endometrial lining to prevent implantation of an embryo, and changing the quality of cervical mucus to limit sperm mobility within the uterus and fallopian tubes.

As a result, hormonal contraception leads to a temporary – and in some cases long-term – suppression of fertility. Certain forms may also exert an early abortive (anti-implantation) effect, as they prevent a newly formed human embryo from implanting in the uterine lining during the earliest stages of development.

The known mechanisms of action include:

• thickening of cervical mucus, which restricts sperm penetration into the uterus and fallopian tubes;
• disruption of ovarian follicle maturation or inhibition of ovulation;
• prevention of embryo (blastocyst) implantation by inducing atrophy of the endometrial glands and impairing proper development of the uterine lining;
• alteration of fallopian tube motility, including reduced muscular contractions and ciliary movement, which may prevent the embryo from reaching the uterus and implanting at its biologically programmed time (approximately 5-6 days after fertilization).

A commonly accepted claim – particularly promoted by contraceptive manufacturers – is that hormonal contraceptives do not have early abortive effects. This assertion is based on a specific definition of when human life is considered to begin: according to this view, life begins not at fertilization, but at implantation in the endometrium. Under this definition, hormonal pills and intrauterine devices (IUDs) are not classified as abortive, as they cause the embryo’s loss before implantation – described as occurring “before pregnancy begins”. As noted by Dr. Adam Kuźnik, for clarity this mechanism is more accurately referred to as an “anti-implantation effect” of hormonal contraception. Nevertheless, the biological outcome of this mechanism may involve the destruction of a human embryo that is only a few days old.

How do natural fertility awareness methods work?

Natural fertility awareness methods – also known as Natural Family Planning (NFP) – are not contraceptive in nature. Rather, they provide information about a woman’s fertility through careful observation of physiological signs such as changes in cervical mucus, cervical position and texture, and fluctuations in basal body temperature. These signs reflect the underlying hormonal changes of the menstrual cycle. By interpreting these signals, couples can adjust the timing of sexual intercourse in accordance with their family planning intentions. These methods are based on recognizing the woman’s individual fertility rhythm and allow for accurate identification of fertile and infertile days.

The foundation of fertility awareness lies in understanding cyclical hormonal changes and learning how to correctly interpret the associated physical symptoms. Clear and well-defined rules guide both the recognition of fertile days and the identification of periods of natural infertility.

Ultimately, it is up to both partners to decide how to use this knowledge—whether to postpone conception by abstaining from intercourse during fertile periods, or to pursue pregnancy by engaging in intercourse during times of peak fertility.

The use of Natural Family Planning (NFP) methods does not cause any side effects. These methods are not associated with discomfort or health risks and do not pose any threat to a woman’s well-being.

In contrast, the use of hormonal contraceptives is associated with a wide range of adverse effects, side effects, and potential health risks:

• The combined oral contraceptive pill may cause side effects such as nausea and vomiting, headaches and induced migraines, weight gain, decreased libido, spotting and abnormal uterine bleeding, skin changes, and mood disturbances, including a tendency toward depression.

Potential health risks include an increased likelihood of acute myocardial infarction, development of hypertension, venous thromboembolism, increased incidence of breast, cervical, and liver cancers, as well as a higher risk of diabetes and gallbladder disease.

• The progestin-only pill may cause side effects such as weight gain, nausea and vomiting, hair loss, worsening of premenstrual syndrome (PMS), osteopenia and osteoporosis, abnormal blood lipid profiles, skin changes, hirsutism (androgenic effects), hyperprolactinemia, mood changes and depression, reduced libido, vaginal inflammation, ovarian cysts, and transient breakthrough bleeding.

Additional adverse effects may include impaired liver, thyroid, adrenal, and kidney function, disturbances in carbohydrate metabolism and blood coagulation, as well as an increased incidence of ectopic pregnancies and ovarian cysts.

• Contraceptive patches may lead to nausea, vomiting, melasma (brown facial pigmentation), weight gain, reduced libido, vaginal dryness, mood deterioration, headaches, and transient breakthrough bleeding.

Associated risks include thromboembolic disease, coronary artery disease, arterial hypertension, stroke, jaundice, breast cancer, and amenorrhea.

• The intrauterine device (IUD) increases the likelihood of ectopic pregnancy tenfold due to impaired fallopian tube motility. There is also a risk of uterine perforation during insertion and possible expulsion of the device caused by increased uterine contractions triggered by prostaglandins.

In addition, the use of IUDs is associated with an increased risk of pelvic infections and infections of the surrounding tissues, the possibility of systemic infection, and abnormal or heavy uterine bleeding. Intermenstrual bleeding is common, and pelvic pain may intensify.

Natural Family Planning methods require developing an understanding of one’s own body – specifically the cyclical hormonal changes and their effects. They also require consistent adherence to the rules for identifying fertile and infertile days, as well as periodic sexual abstinence during potentially fertile phases. Failure to follow these guidelines or neglecting ongoing observations can reduce the effectiveness of the method.

It is important to take into account factors that may interfere with the interpretation of fertility signs, such as high stress levels, fever‑related illness, or disrupted sleep patterns. These factors most commonly affect temperature readings, although interpretation is still possible based on other observed indicators.

Contraceptives, contrary to appearances, also present various practical challenges. Many medications – including herbal preparations – can reduce their effectiveness. Unfortunately, few package inserts provide detailed information about which substances may diminish the efficacy of oral contraceptives. Any issues affecting absorption (e.g., vomiting or diarrhea) require dosage adjustment. Additionally, user errors such as irregular intake or missed doses can further reduce the effectiveness of oral contraceptives, often making it necessary to use an additional backup method (mechanical or chemical).

Contraception – from the Latin anticonceptio – refers to actions and methods intended to enable sexual intercourse without regard for fertility, removing its natural periodic limitations and aiming to prevent the conception of new life.

Divorce rates among couples who use contraception reach as high as 50%, whereas among couples who follow Natural Family Planning (NFP) methods, the rate is estimated at around 2%. This striking difference reflects contrasting lifestyles and attitudes. Couples who respect natural fertility and care for their mutual reproductive health often relate to one another in a fundamentally different way. Their relationships tend to be based on full acceptance of one another – including the sexual dimension of both woman and man – shared responsibility, mutual care, open communication, self-mastery, and an understanding of fertility as a gift rather than a burden.

One of the core differences between contraception and NFP lies in the sense of responsibility and the quality of the relationship between partners. Among couples using various contraceptive methods, there is often a tendency to shift or avoid responsibility – both toward one another and toward a potential child.

Statements such as “we’re only human” are frequently used to justify giving in to sexual impulses, implying that self-restraint is unrealistic or unnecessary. Yet life regularly presents situations in which temporary sexual abstinence is unavoidable – due to serious illness, high-risk pregnancy, or physical separation. These circumstances highlight the value of developing self-discipline and the ability to master one’s impulses.

Another commonly cited argument in favor of contraception is the appeal to “progress.” Artificial methods of preventing pregnancy are often described as modern because they appear convenient and require little reflection, decision-making, self-control, or accountability. Instead of relying on personal responsibility and trust in the body’s natural rhythms, responsibility is transferred to contraceptive methods that are, in fact, not 100% effective.

The argument of “freedom” is most often voiced by younger people who associate happiness primarily with sexual experience and seek to avoid limits or unforeseen consequences. Yet many couples ultimately find themselves dissatisfied despite this promised freedom and convenience. Relationships may become superficial, overly focused on physicality rather than emotional intimacy, and deprived of dept – leading to a continual search for new sensations, stimulation, and experiences.

The formulation of hormonal contraceptive pills is designed to mimic the second (luteal) phase of a woman’s menstrual cycle – a phase naturally characterized by a Pearl Index of 0.0, indicating infertility. The objective of these formulations is to create a synthetic hormonal environment that suppresses the highest levels of hormonal regulation in the female body, namely the hypothalamic–pituitary–ovarian (HPO) axis.

Hormonal contraceptives can be classified according to their composition as follows:

• The combined oral contraceptive pill contains both an estrogen component and a progestin component. The estrogen component inhibits the secretion of follicle-stimulating hormone (FSH), thereby blocking follicular development in the ovary and enhancing the effect of progestins. The progestin component – administered for 21 days per cycle – suppresses luteinizing hormone (LH) secretion and usually prevents ovulation. In addition, it reduces the quality of cervical mucus, alters the endometrial lining by disrupting its normal proliferative development due to sustained progesterone exposure, and interferes with fallopian tube motility as well as the transport of gametes and embryos.

Potential health risks associated with the use of combined oral contraceptives include an increased risk of acute myocardial infarction, the development of hypertension, venous thromboembolism, a higher incidence of breast, cervical, and liver cancers, and an elevated risk of diabetes and gallbladder disease.

Common adverse effects of the combined oral contraceptive pill may include nausea and vomiting, headaches and migraine exacerbation, weight gain, decreased libido, spotting and breakthrough bleeding, skin changes, and mood disturbances, including a tendency toward depression.

Contraindications to the use of combined oral contraceptives include a personal or family history of vascular disease, ischemic heart disease, heart valve disorders, hypertension, varicose veins, clotting disorders or familial hyperlipidemia, diabetes, liver disease, a history of pregnancy-related jaundice or trophoblastic disease, migraines, and breast or uterine cancer.

• The progestin-only pill (commonly known as the minipill) is effective for 24 hours and should be taken at the same time each day. Its mechanism of action is based on typical progestin effects, including thickening and reducing the quality of cervical mucus, impairing the endometrial lining’s ability to support implantation of a human embryo, and altering fallopian tube motility. During use, estradiol levels remain low, and the growth and maturation of ovarian follicles are diminished. Luteinizing hormone (LH) secretion is reduced, which interferes with proper corpus luteum formation and results in low progesterone levels. However, ovulation still occurs in approximately one-third of women using the minipill. Because natural menstrual cycles are not fully suppressed, the primary effect of this method is not the prevention of fertilization but rather the prevention of embryo implantation; therefore, it may function as an early abortifacient.

Potential harmful effects of the minipill include an increased risk of ectopic pregnancy and ovarian cysts, as well as disturbances in liver, thyroid, adrenal, and kidney function, carbohydrate metabolism, and the blood coagulation system.

Reported side effects of the minipill may include weight gain, nausea and vomiting, hair loss, worsening of premenstrual syndrome (PMS) symptoms, osteopenia and osteoporosis, abnormal blood lipid profiles, skin changes, hirsutism (androgenic effects), hyperprolactinemia, mood swings and depression, decreased libido, vaginal infections, ovarian cysts, and intermittent breakthrough bleeding.

Contraindications to the use of the minipill include a personal or family history of cardiovascular disease, ischemic heart disease, heart valve disorders, hypertension, varicose veins, blood clotting disorders or familial hyperlipidemia, diabetes, liver disease, a history of pregnancy-related jaundice or trophoblastic disease, migraines, and breast or uterine cancer.

• Hormonal contraceptive patches are transdermal preparations containing norelgestromin and ethinylestradiol. The patch is applied once every seven days for three consecutive weeks, followed by a one-week break. The continuous daily release of hormones through the skin results in stable blood hormone levels comparable to those achieved with combined oral contraceptive pills, but without the daily hormonal fluctuations associated with oral dosing.

The mechanism of action of contraceptive patches is similar to that of combined oral contraceptives. They inhibit ovarian follicle development and suppress ovulation, reduce the quality of cervical mucus, slow fallopian tube motility, and induce unfavorable changes in the endometrium.

Potential complications include venous thrombosis, coronary artery disease, hypertension, stroke, jaundice, breast cancer, and amenorrhea.

Undesirable side effects may include nausea and vomiting, melasma (brown facial pigmentation), weight gain, decreased libido, vaginal dryness, mood changes, headaches, and intermittent breakthrough bleeding.

Contraindications to the use of contraceptive patches include liver disease, a family history of cardiovascular disorders, circulatory system diseases, hypertension, prolonged immobilization, smoking, significant obesity, anemia, and systemic lupus erythematosus.

• Progestin-based contraceptives, which are available in the form of injections and subdermal implants. Subdermal implants, which are not approved for use in Poland, contain progestins that are released slowly over a period of up to five years. Injectable contraceptives are irreversible for 2–3 months, during which time the active substance cannot be removed from the body, even in the event of adverse effects. In theory, the return of normal biphasic menstrual cycles should occur within approximately eight months after discontinuation. In practice, however, spontaneous restoration of hormonal function often takes significantly longer. Users may experience irregular, unpredictable, light bleeding or complete amenorrhea. The effects of injectable contraceptives – particularly after the ninth week following administration – are similar to those of the progestin-only pill (minipill), and they are associated with comparable mechanisms of action and side effects.
• Postcoital hormonal preparations also exhibit anti-nidational (anti-implantation) effects and may therefore function as early abortifacients.

Suppression of ovulation through the administration of high hormone doses is effective only within a limited time window – specifically, during the several dozen hours preceding ovulation. In practice, women often take these high hormone doses without knowing which phase of their cycle they are in, and such doses may disrupt the physiology of several subsequent menstrual cycles.

Emergency contraception may be administered using various regimens, including: a high dose of progestins taken as soon as possible, followed by a second dose 12 hours later; ethinylestradiol administered twice daily for five days; or the Yuzpe method, which combines a progestin with ethinylestradiol and is repeated after 12 hours.

The chemical compounds used in these regimens contain very high concentrations of hormones, which increases the likelihood and severity of side effects.

High doses of hormones are typically administered within 72 hours after intercourse. Beyond this period, secretory transformations of the endometrial lining may already be sufficiently advanced that even large hormone doses are unable to prevent implantation. However, if implantation does occur, endometrial progesterone receptors may be blocked (as with agents such as mifepristone or ulipristal), leading to endometrial shedding together with the embryo.

• Intrauterine Devices (IUDs), commonly referred to as spirals>/b>, are inserted into the uterine cavity, typically during the final days of menstruation. They are usually made of plastic reinforced with an active agent such as copper, silver, gold, or platinum. Some types also contain a reservoir that gradually releases a progestin.

Mechanism of action: like any foreign body, an IUD induces a local inflammatory response within the uterus, leading to the accumulation of large numbers of leukocytes. These immune cells destroy sperm and alter the structure of the endometrial lining, thereby preventing embryo implantation.IUDs that release a progestin act like progestin-only pills: they thicken cervical mucus, modify the endometrial lining, and suppress ovulation in only about 25% of users. During the first months of use (and in some cases up to a year), an IUD may also act as a mechanical barrier that limits sperm access to the fallopian tubes. Over time, however, as the device remains in the uterine cavity, its contraceptive effect becomes primarily anti-implantation (anti-nidational) in nature. This mechanism may function as an early abortifacient by inducing inflammatory changes in the uterine lining that prevent implantation.

Effect on the uterine lining: The IUD exerts its effect by damaging the endometrium. Fertilization may still occur normally in the fallopian tube, but implantation is prevented due to endometrial alterations, resulting in the death and subsequent expulsion of the embryo. Copper-containing IUDs additionally reduce sperm motility and slow the embryo’s transport through the fallopian tubes, which may increase the risk of ectopic pregnancy.

Complications associated with IUD use include: a tenfold increase in the risk of ectopic pregnancy due to impaired fallopian tube motility, uterine perforation during insertion, spontaneous expulsion of the device caused by prostaglandin-induced uterine contractions, increased risk of infections of the reproductive tract and surrounding tissues, systemic infections, abnormal or heavy menstrual bleeding, intermenstrual bleeding, and intensified pelvic pain.

Absolute contraindications for IUD insertion include: recurrent genital or pelvic infections, anemia, irregular bleeding of unknown origin, suspected or confirmed pregnancy, a history of ectopic pregnancy, congenital uterine anomalies or structural abnormalities, uterine fibroids or ovarian cysts, hypersensitivity or allergy to the active components of the device, nulliparity (not having given birth), and immunodeficiency.

• Antiprogestins – the substance used in this group is mifepristone (RU-486), which is not registered or approved for use in many countries.

Mechanism of action: it binds to progesterone receptors, thereby blocking the action of progesterone, a hormone essential for the maintenance and development of a human embryo. It also increases uterine contractility. After administration, a process known as luteolysis occurs, leading to the disruption of the corpus luteum that supports the embryo. Within approximately 72 hours, the decidual lining separates from the uterine wall, resulting in bleeding and the expulsion of the embryo together with the endometrium.

“Any other medicinal product suspected of even minimally promoting cancer development would be immediately withdrawn from the market,” says obstetrician-gynecologist Piotr Gratkowski. “Given that hormonal pills are listed among carcinogenic agents, permitting their continued sale is, at the very least, questionable.”

Despite extensive lists of contraindications, hormonal contraceptives continue to be promoted as the only “modern” solution. Particularly concerning is their use among adolescent girls, in whom the hypothalamus–pituitary–ovary axis is still developing. In adult women, these drugs interfere with the natural hormonal balance, potentially disrupting normal reproductive processes and contributing to fertility problems later in life.

Article based on the following sources:

• “Mechanism of Action of Hormonal Contraceptives. A Comparison of Information Found in Patient Leaflets and Academic Textbooks” by Małgorzata Prusak, Życie i Płodność, No. 3/2009
• “On Hormonal Contraception” by Dr. Elżbieta Siwiak, INER Scientific Notebooks, Issue No. 3/2005
• “Contraception – Questions and Answers” by John Guillebaud, Medycyna Praktyczna, Kraków, 2005