Are Human Fetuses Parasites? (revised 5.6.19)


Occasionally abortion-choice advocates refer to fetal humans as parasites. We know what they are getting at. The child-in-utero is dependent on the mother, drains her energy, eats her food, etc. But, is “parasite” the right idea here? Are fetal humans really parasites?

No, fetal humans aren’t really parasites.

“Parasite” is a different relation entirely from the mother-child relation. That said, there is a strained sense in which fetal humans can be considered “parasites,” but it’s not really fair or consistent to treat them as literal parasites because in the biological sense children-in-utero aren’t parasites. We know this for several reasons.

Problems with the Biological Sense of Parasite

1. Fetal humans are the same species as their parents.

Tapeworms or hookworms or leeches can all be parasites as they are not the same species as the host animals they infest. Pregnant human mothers carry human children. Their pregnancy always refers to human offspring. Being the same species, the child is not a parasite in the normal biological sense of “parasite.”

2. Standard references uniformly categorize fetal humans as homo sapiens.

Supporting the last point, no textbook or standard reference in embryology or fetology categorizes the human fetus as a parasitic organism but as a fellow member of the genus and species: homo sapiens. Literally and strictly speaking, that means fetal humans, from conception onward, are a member of the human race, and a part of the human family. Calling them “parasites” wrongly implies they are some harmful outside invader when, in reality, the fetal human is exactly where natural, healthy, human procreation placed him.

3. Parasites are inherently harmful to their host while the child-in-utero is not inherently harmful to the mother.

The normal or “natural” disposition of parasites is harm, danger, and disease for the host. that’s just how parasites work. If any parasite were to cease being harmful to it’s host, it would no longer be a parasite but a symbiote with mutually beneficial relationship to it’s host, or they would be cohabitants coexisting without benefitting or harming each other.

Now some pregnancies incur medical complications, and can risk the mother’s health or life, but that’s not an intrinsic or normal part of every pregnancy. Consider, for example, how some car rides end in a traffic accident. Just because some car rides lead to a crash that doesn’t make every car ride an inevitable car accident. The danger from parasites is normal and intrinsic with every parasitic relation. Every parasite is harmful to it’s host. For any pregnancy to count as a parasitic relation, every pregnancy would have to be a harmful parasitic relation.

4. Parasites are parasitic regardless of their developmental stage.

Parasites are defined by their draining/harmful relation to their host, and not by their stage of development. They are parasites regardless of their developmental stage. Parasitic worms like tapeworms, flukes, hookworms, and pinworms, survive just fine as larvae or adults, inside of human digestive tracts. Other smaller parasites (parasitic protozoa) likewise exist in a parasitic relation to their host in the body regardless of their stage of development. the same applies to ectoparasites like ticks, mites, leeches, and fleas. They are parasitic across several developmental stages including adulthood. If children-in-utero start as parasites in the womb, they’d need to be parasites even after birth and on to adulthood since parasites don’t stop being parasites just because they “aged-out” of the system. Parasites are parasites whether they are eggs, larvae, babies, or adults.

5. Fetal humans don’t fit into the three categories of parasites.

As mentioned above, there are three types of human parasites: protozoa, parasitic worms (helminths), and ectoparasites. Fetal humans aren’t protozoa or worms. And since they gestate entirely inside the womb, they can’t be ecto-parasites, that is, external parasites, like lice, mites, and ticks. So fetal humans don’t fit into the the established categories of parasites.

6. Not all dependence is parasitic.

Across much of the animal kingdom, and all of human society, offspring are dependent on their elders. Later in life, the senior members are dependent on the younger members. “Dependence” is not a sufficient criteria to qualify someone as a parasite. If we redefined “parasite” to include all dependency relations, that would indict most everyone since civilization itself is deeply interdependent across all social strata. Spreading the word “parasite” that thin is revisionary, and problematic – draining the word of it’s normal and classic usage, while insulting pretty much everyone for not being radically independent. Meanwhile, it’s the normal convention of society, whether human or other higher order animals, for young members of the species to be deeply dependent on their family and community. That’s no parasitism, that’s just society.

7. Mammalian mothers are psychologically built to have a healthy nurturing relationship with their gestating child.

The relation of mother and child is intrinsic. It’s a basic physiologically normal and healthy family relationship that includes conception, gestation, birthing, weening, and rearing of the child. And, for what it’s worth, it’s natural. The human body isn’t built specifically to birth parasites, as if the mother’s mammary glands are sized just right for suckling hookworms. Parasites are opportunistic, they can invade and leech off resources in the digestive tract, the bloodstream, or the skin. But fetal children can survive only in the mother’s womb, until viability when they can survive outside of the womb.

8. Humans need fetal offspring, but host species don’t need their respective parasites for thriving and survival.

Humans can thrive and survive just fine without any tapeworms, leeches, or parasitic microbes. But the human race would go extinct if we had no fetal humans. While parasites serve no greater good for the human race, children-in-utero are our only hope for survival as a species. The mother-child relation, in pregnancy, is the fundamental means of reproduction, the primary relationship for sustaining the human race. That’s the opposite of a parasite. Parasites prevent the host from thriving, harming, crippling and sometimes killing them before moving on to another victim. The parasite’s survival is a zero-sum exchange with the host. If the parasite thrives, the host does not. If the host thrives, the parasite does not.

9. Mother-child relations are symbiotic, not parasitic.

The relational dynamic between mother and child is more symbiotic than parasitic. The mother and child both stand to benefit from the relationship. The benefits of pregnancy aren’t just abstract ideas about “fulfillment,” “purpose,” and “family.” Studies are showing a range of practical benefits of pregnancy including improved cognitive function, reduced painful menstrual cramping, greater compassion/empathy towards others, and even reduced risk of certain diseases like breast cancer, ovarian cancer, and heart disease.

But fetal humans are still parasites in some sense, right? 

Now that we’ve seen that fetal humans aren’t parasites in the normal, literal, sense of the word “parasite.” The English language is still flexible enough to where we can justifiably categorize any dependent relationship as “parasitic.” Your uncle Karl might be a parasite off of Grandma Bessy. And Jimmy might be a “social parasite” leeching off and accomplishments of others, without contributing anything positive himself.

In this loose, non-biological sense of “parasite” babies, in the womb or out, are parasitic –whether preborn or not–in the sense that they feed off of the nutrients fed to them through their mothers, and they are utterly dependent on their mothers. But even then, “parasite” is a poor choice of words because it implies only harm toward the mother when, in reality, she stands to benefit physiologically and relationally if she’s willing to carry that child to term. Nevertheless, if we are only focusing on the “dependency” aspect of parasites, fetal humans, babies, toddlers, and teenagers are all parasites.

In that strained sense of parasitism, human beings stay parasitic through much of their life. Parents of teenagers can attest to how their children are not fully functional adults without their insight, care, and provision. Handicapped adults or senior adults can also be deeply dependent on others, even harming their respective “hosts” by needing more of them than can be provided.

So the case can be made that people at most any stage of life are capable of being parasitic, even if, strictly and biologically speaking they aren’t parasites.

Problems with the Colloquial Sense of Parasite

1. Loaded Word Fallacy: “Parasite” is part of rhetoric strategy attempting to dehumanize and degrade children-in-utero so it’s easier to morally justify killing them.

Now, where does this exercise get us? It is a well-known aim of pro-life advocates to emphasize all the dignifying terms for the human fetus–baby, child, human, human being, boy/girl, person, etc. Meanwhile, pro-choice advocates are known to emphasize demeaning terms for the human fetus–such as fetus, tumor, a clump of cells, or parasite.* Presumably, if we grant one of these dignifying or demeaning titles for the human fetus we risk granting the whole batch of correlated terms – either humanizing or dehumanizing the fetal human. one has granted some of its correlate ideas.

Parasites are weed-like animals, unwanted, unsightly, something to be rid of. Insults, however, do nothing to change the biological status of a human being–and biologically the human fetus is literally a human being. Even if a human being were parasitic, he or she would still be a human being potentially carrying all the innate rights therein, whether that human is your brother-in-law, your great grandmother, or the child in your wife’s womb.

The “parasite” affiliation runs the risk of a “loaded word” fallacy, proving nothing in directly logical terms but instead slandering the preborn child with connotations of “weed,” “unwanted,” “harmful,” and “deadly.”

2. Insufficient Cause: Even if a human was acting as a parasite, that alone isn’t enough to justify killing a fellow human being.

To justify killing a human being, something more than “parasite” would need to be established, such as “deadly assailant” or “murderer” or “rapist.” That case can be made if the child represents a distinct medical threat to the mother’s life, such as with tubal pregnancies or other complicated pregnancies. The baby is instrumentally threatening the mother’s life, and so it would not be a loaded word but an apt description to call that preborn child–instrumentally deadly to the mother.

Perilous pregnancies are unfortunate but real, and when they happen that child’s presence threatens the life of the mother, and might be justifiably aborted on the grounds of self-defense. Those sorts of cases are widely admitted justifications for killing a human being, but apart from tubal pregnancies (and similar cases) the death penalty just doesn’t apply. The child is not a “Murderer” or a “rapist” or a “traitor.” He (or she) does not deserve the death penalty. Those terms don’t apply.

3. Disanalogy: The mother-child relation is substantially different from a burglar/trespasser/malicious-intruder/etc.

One might argue that the child is a “trespasser” and it’s legal in many states to shoot and kill a trespasser. It’s not legal, however, to kill a person whom your actions are the natural and historic means of inviting onto your property. Sex has been nature’s way of inviting a baby into the womb since time immemorial. The baby is not a trespasser, he’s an invited guest. Even with contraceptive practices, one is still inviting a child into one’s “home” despite the fencing and locked door. Sometimes that child still gets in the house, since you’ve still performed the natural actions that sometimes place that developing child in utero – through no fault of his own. That child was forced into existence, and placed in-utero, without any choice in the matter.

4. Non-Sequitur or Ad Absurdum: Either fetal “parasites” should all be killed because they are harmful (ad absurdum) or parasitism doesn’t support the pro-choice position (non-sequitur)

The “parasite” affiliation is also a non-sequitur or an ad absurdum argument. Non-sequitur means “does not follow.” The pro-choice position does not follow consistently with the “parasite” accusation. But it does align with some absurd outcomes which most pro-choicers don’t support.

Even if we granted the pro-choice rhetoric of “parasite”, it doesn’t follow logically to a pro-choice position since all human beings go through a parasitic stage in utero and therefore should be destroyed. Parasites are bad and should be killed or at least expelled as soon as possible. But pro-choice advocates aren’t trying to get every mother to abort. They just think mothers should have the choice to abort if they wanted to. But if fetal humans are parasites then all pregnant mother’s should abort their children just like everyone should get vaccinated.*

It does no good to distinguish between “wanted” and “unwanted” children-in-utero either. Parasitism is a relationship, not a desire. The parasite is a parasite even if the host is morbidly content letting that blood-sucker drain the life from her. A parasitic relation defines the parasite, and it’s entirely irrelevant whether the mother wants the child or doesn’t want the child-in-utero. That child-in-utero, if a parasite, should be killed for the mother’s own good.

5. Dependent Children should be loved and cared for, not killed.

We can admit that children, born and preborn, are very dependent human beings, desperately needing their parents. But just as puppies and kittens need extra love and care, so do baby humans. Their dependence is a reason to love them tenderly and care for them selflessly. Their dependence hardly excuses neglecting and killing them, as implied by this pro-choice lingo.


*And for anti-vaxers, they should take whatever measures are practically equivalent to preventing measles, mumps, etc. The point is not about the legitimacy or illegitimacy of vaccination in particular, but about the importance of disease prevention generally.

About intelligentchristianfaith

Married man. Teacher. Theologian. Philosopher. Workout nut. Prefer cats to dogs. Coffee buff. Transplant to Texas. Carolina Panthers fan. Perpetually pursuing the world's best burger.
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3 Responses to Are Human Fetuses Parasites? (revised 5.6.19)

  1. eyeontheuniverse says:

    “babies–whether preborn or not–cannot be parasites because, first, they are of the same species as their parents’

    OED definition “An organism that lives in or on another organism (its host) and benefits by deriving nutrients at the host’s expense.”
    “An organism that obtains nourishment and shelter on another organism.”

    Where are you getting a definition that specifies different species?


    • Eyeon, “By definition, parasites are those animals which occupy the last niche [in the list of terrestrial, aquatic, and biotic], i.e. live in or on another species, their host. Parasitism is a form of symbiosis, an intimate relationship between two different species.” ( Another medical source from UPENN agrees pointing out how the parasitic relation is between two species. Other sources, offering less detail, have been known to point out their harmful relation to their host (see “parasite” and “parasitism” in this health resource).

      The OED is a good general dictionary, but when it comes to medical, legal or philosophical definitions, the respective sort of dictionary is more appropriate.


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