The foetus-parasite fallacy

Misconceptions: Is a foetus a parasite? 

Yes this is how I have decided to start my first article-with a silly question. For a long time I have been one of those who linked pregnancy with carrying a parasite. That may be due to my love of shocking others with that correlation, being childish or my fear of pregnancy. 

But going back to the question. Is a foetus a parasite? Just a wanted (sometimes...) parasite. 

According to the CDC a parasite is 'an organism that lives on or in a host organism and gets its food from or at the expense of its host'.  One of the three classes of parasites is protozoa (such as Cryptosporidium) which are 'microscopic, one-celled organisms that can be free-living or parasitic in nature', and 'are able to multiply in humans, which contributes to their survival' to cause 'serious infections to develop from just a single organism'.  How does that not sound like a foetus! 

1) Throughout pregnancy, the foetus relies entirely on the mother to supply it with nutrients and all that good stuff.

2) A zygote is microscopic, similar to a single celled parasite. 

3) The zygote then divides and keeps on dividing, increasing size. Until the blastocyst stage, the cells that make up this morula are the same. This division is therefore similar to Cryptosporidium asexual (merogony) reproductive cycles. 

4) Ectopic pregnancies can lead to infections!

The development of an embryo- Fertilization to Blastocyst

Does this mean that a foetus can be seen as a parasite and I'm not wrong in correlating the two? 

Guess what I AM WRONG. Before I go into why I am wrong let me rant. 

Everything can be linked/correlated/showed with some silly experiment, explanation etc however that does not mean it is right. Through researching topics I am interested about online, I have realised how much false information is loitering online. Everyone can link something to another just like I have above, however correlation does not equal causation (yes that has been brought up). We all know it, yet when something is written in a 'scientific article' manner it is seen as legitimate. In simple terms, do not trust everything you read. Research properly. This is particularly aimed at the ANTI-VAXXERS online. Treat yourself by educating yourself a bit more. Rant over. 

Back to the real issue. On my journey of exploring why and how a foetus is not a parasite, this is what I found. A FOETUS IS NOT A PARASITE (FOR MANY REASONS let the list begin).

1. A parasite is an invasive organism of one species that lives in or on an organism of another species and receives nourishment from the host. A foetus however originates from an internal same species source. 
2. Parasites are generally harmful and unneccesary to the hosts, foetuses may make a pregnant woman experience adverse health effects, but not nearly to the same level that a parasite generally does. Post birth, a baby is usually advantageous to mother as it brings hormonal and chemical changes that are benificial. 
3. When a parasite invades a host making direct contact, the host tissue will usually respond by encapsulating the parasite in order to cut it off from other surrounding tissue. In the case of a fetus, the placenta composing of the chorion developed from the fetal blastocyst and the decidua developed from the uterine lining. This creates a lining tissue that connects indirectly, rather than cuting off contact with the foetus, distributing nutrients between mother and foetus to ensure health of both suggesting a symbiotic relationship. Easy peasy. No competition. 
4. Parasites usually elicit a surge of antibodies as an immunological response. With the foetus, a mother’s trophoblast will block these antibodies so as not to reject the foetus. The trophoblast and maternal immune system have evolved and established a cooperative status, helping each other for the success of the pregnancy. This reaction is only found in the embryo-mother relationship.
5. A parasite will usually weaken the cellular reproductive capacity of the host. For a fetus, the effect is the opposite.
6. Although not always the case, many parasites remain within the host for life. This certainly isnt what a foetus does as it develops and grows to be sassy baby after birth. 

Of course there are exceptions to these rules of differential species, reducing prospects of host survival etc which can be seen in the jellyfish narcomedusae (the baby jelly fishes get nourishment and safety from their mothers, them leaving to gain nourishment from another species. However some can remain and get their nutrients from adult jellyfish. This however is the baby not the foetus that turn into parasites) and japanese folliage spider (they uses their mother as food, eating her alive for dinner). 

Japanese Folliage Spider

However, a human foetus is NOT equivalent to a parasite.