Should my aliens repair external defects?

[caters]

This is 1 thing that I haven't been able to decide on. Whether or not external defects get repaired. Now of course cleft lip and cleft palate which are external defects get repaired but what about other external defects? For example a baby could be missing an entire arm and just have a shoulder on that side.

This is just 1 baby that is missing an arm, in this case, its right arm. And it was born that way.

But should my aliens repair all external defects or just leave them as they are?

I know that they repair all internal defects like for example having 1 ventricle in the heart with no ventricular septum.

Forming a ventricular septum is relatively fast. Even forming a whole lung is relatively fast.

But forming an arm is much more complicated. They would have to form all these in proportion:

• Bones
• Muscles
• Tendons
• Ligaments
• Arteries
• Veins
• Cappilaries
• Nerves
• Skin
• Lymph vessels
• Lymph nodes

 That is a lot and it could take years to form an arm and then hours to attach the arm and make sure it is working. But they can't just let the baby be in surgery for years, that is impractical. Besides the aliens don't have formula so the babies have to be breastfed or they die. No matter how much pain it is for the baby or the mom, they have to get breastmilk into the baby. Of course there is 1 exception to this. Babies born with a digestive system defect like a volvulus or atresia or pyloric hypertrophy and stenosis won't be breastfed until the defect is fixed. But otherwise, the baby must be breastfed.

  And there are a lot of things that could go wrong in surgery or after surgery. The baby could bleed out due to a microscopic size hole in the blood vessels and even if the baby didn't bleed to death, it would most likely lead to Iron Deficiency Anemia. The baby could become cyanotic in that arm due to a blood vessel mismatch, the arm could be permanently numb, and the list of complications just goes on and on.  

While some things like Iron Deficiency Anemia are easy to treat, other things like numbness are so complicated to treat that it isn't worth it.  

So should my aliens repair all external defects despite the complications that could result and the time it takes or should they just leave them as is(except for cleft lip and cleft palate which always get repaired)?