In Paraguay, no specific legislation currently outlines in vitro embryos and ARTs (17), leading to a lack of legal protection for embryos that have not yet been implanted (15, 16). This has resulted in a lack of clarity regarding the scope of constitutional rights.

Paraguay's regulatory framework is articulated based on constitutional norms that guarantee the protection of the right to life, reproductive rights, and access to reproductive health plans. International treaties, incorporated into domestic laws, constitute a component of these regulations. The rights and principles enshrined in these instruments serve as guides for protecting life during the early stages of development (Table 1).

The Constitution guarantees the right to life from the moment of conception, as stipulated in Article 4. This protection is reinforced by the incorporation of international treaties ratified by law, including the American Convention on Human Rights (ACHR) (18, 19), International Covenant on Civil and Political Rights,² and Convention on the Rights of the Child.³ However, the precise meaning of the term “conception” remains a topic of contemporary debate, particularly regarding its exact beginning, which is crucial for rendering rights effective (22).

The Paraguayan Civil Code acknowledges the inception of a natural person from the moment of conception, albeit without delineating the precise instant at which this occurs. In the absence of any explicit reference to ‘in the mother's womb’ in the Civil Code to denote conception, the domestic legal doctrine has endeavoured to bridge this interpretive gap. Consequently, it can be inferred that human life conceived via IVF is legally safeguarded (23).

It has been argued that the conception of a new human being should be viewed as the moment when fertilisation occurs, either inside or outside the mother's womb, through ARTs in a laboratory (23). This perspective holds that the embryo, whether implanted or not, has personhood and is entitled to legal protection, albeit in a limited and conditional manner, because it must be born alive. Therefore, the destruction of embryos is equivalent to that of human life (24–27).

Paraguay's judicial system has been subject to contentious issues. In 2018, an amparo⁴ action was initiated, which led the courts to examine the legal safeguards for the embryo in the case of ‘Amparo promoted by MCGG v PG Director of Clínica G’. The plaintiff's main request was to compel the clinic to continue with IVF treatment, which had been halted because of the male donor's refusal to proceed with the final stage of embryo implantation into the mother's uterus. The Adolescent Criminal Appeals Chamber of the Capital, resolved to grant the protection action, promoted and, consequently, forced the clinic to continue the embryo implantation procedure. The Chamber argued that the National Constitution establishes the right to life from conception, interpreting the term conception as the moment of fertilisation of the oocyte with sperm. Therefore, denying embryo implantation in the mother's womb would be an attack on the right to life (29).

The Chamber conducted an exhaustive analysis of domestic legislation, commencing with the Constitution, which safeguards the right to life from the moment of conception. Subsequently, it referred to the Penal Code, wherein it equates the terms ‘embryo’ and ‘foetus’ for the purpose of protecting the right to life, thereby establishing that anyone causing the death of an embryo would be subject to the criminal offence of abortion.

Additionally, the Court cited the Civil Code and the Code of Childhood and Adolescence, which grant protection to unborn individuals from the time of conception. The Court provided an interpretation of the term ‘conception,’ asserting that it should be defined as the moment of fertilisation, irrespective of whether it occurs within or outside the mother's womb (30). Considering this interpretation, the Court decided that conception had already occurred in the case under examination.

After thoroughly examining the issue of the commencement of the right to life, the Court attended to the claim made by the male donor that his readiness to revoke informed consent for treatment should be considered. In this regard, the Court employed the Estoppel⁵ judicial device to fortify the irrevocability of informed consent, grounded in the fact that the male donor, who agreed to undergo treatment by signing a contract, was obligated to engage in conduct consistent with this commitment.

Finally, the Court decided to grant a protective order and ordered the clinic to proceed with the implantation of the embryos in the petitioner's uterus. This ruling highlights the balance of rights between the right to life on one hand, and the right to privacy and not wanting to be a father, on the other, offering a conclusion that could contrast with the position assumed by Paraguay, specifically regarding that of the Inter-American Court of Human Rights (IACtHR) in the ruling Artavia Murillo vs. Costa Rica.

Regarding the analysis of the doctrine and the preceding ruling, it is evident that conception is linked to fertilisation. This indicates that life begins at the instant the oocyte is fertilised by sperm and is not contingent upon whether this occurs spontaneously or through artificial means in the laboratory. An in vitro embryo is categorised as analogous to the classification of unborn individuals in the Paraguayan Civil Code. This designation implies that the embryo is entitled to rights commencing from the moment of conception, under the condition that it is born alive.

The legal status of human in vitro embryos ranges from being considered a person to being viewed as mere property. The concept of an embryo as a person from conception is debated, with some arguing that life is a continuum from conception to death and that the transition from potential person to person occurs at birth (32).

The perspective that human life commences at the moment of conception, which is characterised by the fusion of male sperm and female oocyte, is a prominent viewpoint in the domain of reproductive rights. This perspective emphasises the emergence of a distinct biological entity with a unique genetic legacy (33) entitled to legal and ethical protection from the moment of conception. This viewpoint significantly influences the legal and political discourse regarding the rights of the embryo and its protection, particularly in debates surrounding ARTs, cellular research, and reproductive rights. The significance of this perspective is evident in its impact on shaping the laws and policies related to the inception of human development.

Another relevant aspect of this discussion is the nesting perspective, which posits that human life commences at the moment of embryo implantation in the uterus, a process that occurs between days 8 and 9 after fertilisation (34) (Figure 1). This stage signifies the onset of pregnancy, which can be identified by the presence of the human chorionic gonadotropin hormone in women (3).

Advocates of the nesting perspective argue that, with nesting, the new individual acquires traits that define uniqueness or the quality of being unique, and individuality or the quality of being one (35). Prior to nesting, an embryo can divide and produce identical individuals (monozygotic twins) (27), and a large number of embryos can be discarded naturally (36). Therefore, there is a certain possibility of development only after implantation, and with this, the embryo becomes a subject of protection. The coexistence of an embryo and its mother is necessary for the embryo to have the elements required for its development and growth; this condition occurs only at the time of implantation (3, 37).

The central nervous system formation offers a unique perspective on this debate, arguing that a pivotal moment in human life is linked to the formation of the primitive nervous system, which is a process that occurs after nesting. This development occurs during the gastrulation phase, when the embryo transforms from a bipartite structure consisting of the epiblast and hypoblast into a three-layer configuration composed of the ectoderm, mesoderm, and endoderm. During this transition, the first signs of nervous system formation are evident (38).

Advocates contend that the inception of cerebral activity signifies the initiation of human existence because the capability of the brain is a distinguishing characteristic of human beings in relation to other life forms. Experts typically concur that this stage occurs approximately 14–15 days after fertilisation (3, 27).

Proponents of granting protection posited that the embryo, with its potential for human life, should have the same status as a child or adult (39). Conversely, critics have argued that since an embryo is composed of cells, it should not be considered a person until implantation in the womb, and thus should not be conferred a special protected status. This reflects the tension between viewing the embryo as potential human life and as a cluster of cells (40).

The Warnock Report⁶ (WR) of the United Kingdom serves as a prominent illustration of applying the central nervous system formation in a legal context (41). This report was produced by a panel of experts commissioned to provide recommendations on ART. WR centres on the significant question of the embryo's status, eliciting different viewpoints. The decision to use the formation of the “primitive streak” in the early embryo as a basis for the 14-day rule was a key decision. This rule has been used as a guideline for experimental research in this field for decades (42).

WR declined to address the ontological question of whether an embryo becomes a person or provides a definitive response. Instead, it emphasises the need to treat embryos ethically (43). The report argued that the embryo should be legally protected from day 14 of gestation (14-day period post-fertilisation), which coincides with the emergence of the primitive streak of the nervous system (12). The primary consequence of this conclusion is that scientific research is permissible with embryos that develop up to day 14 of gestation and forbids research on embryos after the 14th day of existence (44, 45).

WR justified the 14-day restriction by presenting both utilitarian and scientific arguments. Utilitarian arguments emphasised the potential advantages of research, whereas scientific arguments were largely influenced by the advice of embryologist Dr. Anne McLaren, who believed that individual human life begins around the time when the appearance of the primitive streak of the brain is observed (46). However, WR recognised that the 14-day limit was an arbitrary compromise designed to alleviate public concerns and provide scientists with the necessary time and conditions for experimentation (43, 47).

Legal systems exhibit significant diversity in their approaches to defining and regulating the legal status of embryos. This diversity is shaped by a combination of scientific, ethical, religious, and socio-political factors that influence both statutory laws and regulatory practices.

Countries such as Austria, Canada, France, Germany, Japan, the Netherlands, and Singapore leave room for interpretation within regulatory guidelines, allowing flexibility in application. This strategy can lead to ambiguity but also enables adaptation as new medical knowledge emerges. Other countries maintain minimal or no formal regulations regarding ARTs, where professional bodies may issue guidelines but lack legislative authority (7, 48).

Australia's ART Act 2024 is being implemented in stages. The primary objective is to enhance public confidence by introducing increased oversight, transparency, and safeguards. The legislation prioritizes the welfare and interests of individuals undergoing ART procedures and emphasizes the well-being of ART-conceived individuals (49).

Switzerland initially had restrictive ART laws prohibiting the culture of more than three zygotes. This led to the transfer of cleavage-stage and multiple embryos to avoid the risk of no embryo being available for transfer on day 5, resulting in high rates of multiple births. In 2017, Swiss ART regulations became more permissive, allowing up to 12 zygotes to be cultured and cryopreserved as blastocysts. This has led to an increase in single and blastocyst embryo transfers, reducing multiple births. Legislative change also caused an increase in both fresh and frozen embryo transfers and a shift from cleavage-stage to blastocyst transfers (50).

In the Philippines, the Reproductive Health Law is among the most controversial pieces of legislation. In a country with a predominantly Catholic population, various religious and conservative groups have questioned its constitutionality and actively sought to delay or block its implementation. While reproductive health care is defined as access to a full range of methods, facilities, services, and supplies that support reproductive health and well-being by addressing related issues, it does not include any mention of ARTs in its provisions (51).

In regions such as Muslim-majority countries, religious doctrines exert a pronounced influence, and ART regulation has been shaped by both legislative actions and fatwas⁷, which serve as guidelines within Sunni Muslim contexts. While these fatwas have guided regulatory developments for subsequent regulations, their dissemination and implementation have varied widely (53).

Understanding Paraguay's legal stance for the protection of in vitro embryos requires contextualisation within comparative legislative models. Different jurisdictions have addressed embryo protection through ‘value-oriented,’ ‘procedure-oriented,’ or ‘hybrid’ regulatory approaches (54). A comparative analysis reveals variation in how legal systems protect in vitro embryos, allowing for a more precise assessment of Paraguay's position within the global spectrum of reproductive rights legislation. Here, we selected the United Kingdom, Spain, Argentina, and Italy to represent the three regulatory approaches (Table 2).

These approaches differ based on specific legal elements (55, 56): (i) legal status of in vitro (non-implanted) embryos, (ii) access to and practice of ARTs, (iii) informed consent requirements, (iv) embryo donation policies, (v) embryo cryopreservation regulations, (vi) disposal of surplus embryos, (vii) use of embryos for scientific research and experimentation, and (viii) pre-implantation genetic diagnosis protocols.

The United Kingdom and Spain apply ‘procedure-oriented’ approaches, influenced by WR and subsequently undergoing legislative reforms (57). Italy exemplifies a ‘value-oriented’ approach, emphasizing the protection of in vitro embryos. Argentina, on the other hand, has embraced a regulatory framework that aligns with the ‘hybrid’ approach. However, it remains in its nascent stage and is somewhat limited in scope compared to other jurisdictions.

The Artavia Murillo v. Costa Rica ruling of 2012 by the IACtHR was a significant legal decision regarding the protection of in vitro embryos, considering various perspectives on the beginning of human life and the use of ARTs (Table 3). This case began with Executive Decree 24029-S issued by Costa Rica's Ministry of Health on 3 February 1995 which authorised and regulated the practice of IVF exclusively for married couples (58).

The decree was challenged because it violated the right to life, leading the Supreme Court of Justice of Costa Rica to declare it unconstitutional and ban IVF treatment. This ruling also prohibited ARTs in Costa Rica. Consequently, many couples were forced to suspend treatment or seek treatment abroad.

IACtHR decision in Artavia Murillo v. Costa Rica was significant in protecting women's procreative autonomy and reinforcing an interpretation of the ‘right to life’ that favours procreative autonomy. It revoked a previous decision by the Constitutional Chamber of Costa Rica which banned IVF (59). The ruling emphasised reproductive rights as a human right and placed women's rights over embryo rights. It differentiated between fertilisation and conception, arguing that the legal protection of an embryo from conception does not apply between its creation by fertilisation and implantation in utero (6).

Costa Rica was the only country in Latin America that completely banned access to IVF, citing embryos’ right to life. This position was challenged by the IACHR and later by the IACtHR (60). Its influence on other Latin American countries, including laws regarding the beginning of life and ARTs, has been noted (61, 62).

The primary issue with which the IACtHR grapples is the interpretation of Article 4.1 of ACHR, which pertains to the right to life protected from the moment of conception. Article 1.2 of the ACHR defines a person as a human being. The central question is whether in vitro embryos can be considered humans (2). The IACtHR went into the interpretation of the terms, ‘conception’ and ‘in general.’ It asserted that given the absence of a consensus at the beginning of life, the term “conception” should be understood as the moment of implantation. Therefore, it is inappropriate to apply Article 4.1 of the ACHR before this event occurs.

The IACtHR highlights that scientific evidence distinguishes between two crucial moments in embryonic development: fertilisation and implantation. Only after the completion of the second event could conception be considered to have occurred. Fertilisation of the oocyte results in a cell with sufficient genetic information for the potential development into a human being, and the lack of implantation into the maternal uterus nullifies the possibility of development.

Regarding the expression, ‘in general,’ the IACtHR maintained that it allows for exceptions to be made to the principle of protecting the right to life from conception. The IACtHR further supported its argument by emphasising that the right to life is not an absolute right that justifies the complete denial of other rights and that the protection of life is gradual and incremental, varying depending on the degree of development.

The Supreme Court of the Nation in Argentina adopted a unique stance on the issue of conception, asserting that it occurs at the moment of fertilisation (63). Consequently, the Court determined that the embryo should be recognised as an individual from that instant onwards. This interpretation adhered to lower court rulings (64, 65) until the implementation of the new Civil Code in 2015 (66) and Law 26862/2013 (67), which established the regulations for access to ARTs.

After the enactment of these regulations, there has been a trend towards granting embryos special protection without assigning rights until implantation. Argentine courts adopted the same interpretation as the IACtHR in Artavia Murillo vs. Costa Rica, granting rights to the embryo from the moment of implantation, and national norms established the revocability of informed consent until the moment of implantation (68).

On the other hand, the Constitutional Court of Spain has examined the constitutionality of legislation pertaining to abortion (69), embryo and foetal donation and use (70), and ARTs (71). In these deliberations, it adhered to a consistent line of interpretation; while denying the unborn child⁸ the ownership of the right to life, it acknowledged that it deserves special protection as a constitutionally protected legal entity. Consequently, the legality of permissible embryo experimentation has been upheld, provided that it is conducted in accordance with human dignity and sanctioned research on embryos under specific conditions.

The United Kingdom's judicial system, as established in Evans v. United Kingdom, does not consider the embryo as a person with rights protected under the Convention for the Protection of Human Rights and Fundamental Freedoms (73). This viewpoint aligns with the notion that legislation should allow couples to undergo IVF treatment and that couples have the power to revoke their consent at any time before embryo implantation. This approach was later supported by the European Court of Human Rights in its ruling on 7 March 2006 which emphasised that the determination of the beginning of the right to life was within the discretionary scope of the Member States.

According to British jurisprudence, an embryo lacks autonomous rights or interests, and is neither capable of claiming, nor has the right to life claimed in its name, in accordance with Article 2 of the European Convention (74). This understanding highlights the absence of a violation of European regulations in this regard, reflecting the intricacy and diversity of approaches to the regulation of reproductive rights and the protection of the embryo in the European legal framework.

In 2009 and 2014, the Italian Constitutional Court declared unconstitutional the norms of Law 40/2004 that provided in ART the obligation to obtain and implant up to three embryos per reproductive cycle and the prohibition of heterologous fertilisation (75, 76).

In Paraguay, the lack of specific regulations on ARTs has created a significant challenge in forming a legal framework that protects the rights of individuals using these technologies. The domestic legal hierarchy places the Constitution of the Republic of Paraguay as the highest authority, followed by the international treaties ratified by law (77).

The Constitution recognises a supranational legal order that guarantees human rights, peace, justice, cooperation, and development in various spheres (77). Within this framework, Paraguay incorporated the ACHR into its domestic law (78) and accepted the contentious jurisdiction of the IACtHR (79).

The IACtHR introduced the ‘doctrine of conventionality control’ in its rulings, beginning with Myrna Mack Chang v. Guatemala (80–82), and further developed in Almonacid Arellano v. Chile (83) and Trabajadores Cesados del Congreso v. Peru (84). This doctrine allows judges in signatory states to compare domestic laws with international treaty obligations, requiring them to prioritise treaty norms when conflicts arise. In cases where a domestic norm contradicts an international provision, judges may set aside national laws to uphold treaty obligations.

The IACtHR emphasised that upon ratifying an international treaty like the ACHR, states must ensure that domestic laws do not undermine the treaty's dispositions. This involves interpreting national laws in line with the ACHR, as interpreted by the IACtHR, which serves as the ultimate authority on the Convention's meaning (83).

In Paraguay, there are divergent views on applying conventionality control, particularly when a constitutional provision appears to be incompatible with ACHR or IACtHR interpretations. Proponents argue that Paraguay's Constitution endorses a supranational order, requiring alignment with international treaties as per the Vienna Convention ratified by Law No. 289 (85), mandating compliance with treaty obligations. This interpretation supports the modification⁹ of the Constitution to confer constitutional status on international human rights treaties (86).

Critics of conventionality control argue that it lacks normative support within domestic law, where the Constitution is supreme, and assert that international courts should not override constitutional primacy (87). Additionally, conventionality control may pose practical challenges for local judges, who lack the authority to disregard national laws in favour of international ones (87, 88).

In ‘Amparo promoted by MCGG v PG Director of Clínica G ‘ (29), the Paraguayan courts declined to apply conventionality control, adhering strictly to domestic laws rather than following the IACtHR guidelines in Artavia Murillo v. Costa Rica regarding the right to life.

Both, the ACHR and Paraguay's Constitution, broadly recognise the protection of the right to life from conception, yet the definition of ‘conception’ varies, affecting the scope of legal protection. According to the interpretation of domestic courts and the local doctrine, conception is defined as the moment of fertilisation, conferring personhood status on in vitro embryos, and indicating a value-oriented approach.

Adopting the interpretive standards set in Artavia Murillo v. Costa Rica, Paraguay could consider conception to occur at implantation, potentially allowing for ART procedures during the pre-implantation stages. This highlights the challenge of balancing embryo personhood with the use of ARTs.

Comprehensive guidelines for embryo storage, research, and donation are necessary to facilitate the use of ARTs. Domestic laws should also address consent, filiation, and civil liability in cases of embryonic harm or loss to ensure the protection of all parties involved. A particular challenge in regulating ARTs involves the development of legal processes to resolve conflicts between the rights of ART users and in vitro embryos.

The only legal case concerning ARTs in Paraguay involved an amparo action. This type of action does not result in a final decision, allowing for further litigation with expanded terms and evidence. To handle ART-related disputes effectively, procedural law should evolve to provide mechanisms for timely and thorough judicial responses, promote access to justice for all parties, and ensure comprehensive consideration of evidence and arguments.

Even as Paraguay continues to address local legal and ethical hurdles in regulating ARTs, certain emerging technological challenges demand attention. To navigate through these evolving issues, Paraguay must foster national debate involving politicians, judges, medical professionals, bioethicists, and researchers. Such dialogue is critical for developing adaptive frameworks that balance ethical considerations, constitutional principles, and implications of scientific progress.

The proposal to extend the culture period of human embryos in the laboratory from 14 to 28 days has the potential to significantly reshape our understanding of human development (41, 89) and necessitate a reassessment of the moral value attributed to embryos during the earliest stages (90).

Genome-editing technologies represent a dual-edged sword in embryonic research. While these tools hold immense clinical promise, they also introduce putative risks, such as off-target effects, which require careful oversight (91).

Additionally, the development of human embryo models derived from stem cells, which can mimic stages beyond the 14-day post-implantation period (92), blurs the lines between naturally occurring and laboratory-produced embryos, creating a regulatory gray area.

The advent of unisexual reproduction has raised various legal considerations,¹⁰ and the possibility of producing nonviable embryos using synthetic DNA¹¹ technology has raised more questions about the moral status of human embryos.

Breakthroughs in artificial womb technology, initially designed to improve outcomes in premature infants (95, 96), open new possibilities but also provoke debates about parental rights and the legal status of entities developing within these systems. The terminology used to describe these entities has also come under scrutiny and some researchers argue that terms like ‘neonate’ are inappropriate due to their implication of live birth, leading to the proposal of alternatives, such as ‘foetonates’ or ‘foetal neonates’ (97).

These discussions require clear definitions and updated legal frameworks to address possible implications. It is essential to conduct a comprehensive regulatory review to balance potential benefits with respect to human dignity (98).