For instance, new advancements with IVF have opened the doors to embryo selection based on intelligence and IQ. The company Genomic Prediction uses polygenic risk scores to catch embryos which "are genetic outliers, giving prospective parents the option of avoiding embryos with a high chance of an IQ 25 points below average".

Furthermore, MIT predicts that selecting embryos for intelligence could boost babies' IQ by 15 points.
Enhancement, especially when it comes to increasing the intelligence of future humans, is therefore in line with the principle of beneficence. 

Robert G. Edwards, who pioneered the invention of IVF, was a leader of the Eugenics Society of Britain.
Negative eugenics is is when "undesirable traits" are weeded out of society through forced sterilisation or genocide. Post-WW2, this was seen as too extreme. Instead, positive eugenics were seen as the better alternative. This approach focuses on selectively breeding favourable traits so that they eventually overtake all others.
As someone who subscribed to this ideology, Edwards, in creating IVF, gave eugenicists a tool that would aid in accomplishing their goals. He even stated that he wanted IVF to be used non-medically. So, while IVF isn't inherently eugenic, its unintended consequence is that it is necessary for modern eugenics.  

Parents hope their child succeeds in life and, if given the ability to do so, would give their child any advantages possible. But what we deem as advantageous can be problematic, especially in terms of physical traits. It is important to take into account that no one is immune from prejudice. When it comes to enhancement and picking certain features, "'[t]hese kinds of decisions can feed into...discrimination, not fight against it’'".  
In reality, selecting any superficial trait over another could not really be "enhancing" a person, since beauty is subjective. But what is cause for concern is that people consider certain features to be superior than others in the first place. Especially when those trait preferences are often rooted in racism, using IVF in this manner would reinforce those ideas.

Regardless of the stance someone takes regarding IVF and the extent to which it should be used, it is undeniable that the technology is evolving and becoming increasingly popular. A potential unintended consequence would be the practice becoming common among an uninformed public. Instead, promoting IVF for enhancement (which is very attractive to people) will help to educate the masses and encourage the responsible use of IVF.

After researching this subject, my personal opinion is that IVF and PGD should not be used for the purpose of selecting non-medical traits.
My main concern with IVF for enhancement is how it can be used to perpetuate various forms of discrimination.
Though parents having preferences for certain features isn’t necessarily a problem at the individual level, historically, the extent to which some may go to attain these traits has been extreme. To achieve their vision of racial purity, eugenicists want to selectively breed out humanity’s “undesirable traits”. To them, a tool like IVF would be helpful in accomplishing this, and the fact that its creator openly subscribed to this ideology is a big red flag.
Another unintended consequence of IVF is how it can perpetuate sexism. IVF can contribute to prenatal sex discrimination as sex is very easy to screen for. We’ve already seen the consequences of this technology being adopted for this use, as it creates a shortage of women and an oversupply of men. 
These negative impacts demonstrate the way that, when used for enhancement, IVF violates critical bioethical principles.
The consequences of using IVF for enhancement, to me, massively outweigh its benefits. I think that IVF even being available to parents is already upholding their reproductive freedoms, and to limit the use of this technology just to screening out illnesses would not infringe on their bodily autonomy. 
Now, the question becomes what is considered a disease versus a superficial characteristic, given that not all conditions fall obviously into either camp. Where do we draw the line?
While this is up to personal opinion, I think that anything that threatens the health or well-being of the child could be designated as an illness that IVF could be used for. But traits that are otherwise neutral and would not endanger the child's health should be off-limits. 
To put it simply, just because we can does not mean we should.