Getting pregnant at 20, is it acceptable?

It's not the norm in majority of countries nowadays but it's not extremely rare either. I mean, there's people getting pregnant even at 15-16 so...

I don't see anything wrong with it. As long as you're mentally ready and can provide a good environment for the newborn. 

My colleague is 21 and she's thinking of starting a family

If you have the money and have a father for the child, why not?

There are advantages to being pregnant when you are 20 years old. At an early age, the woman is typically quite healthy. There aren't likely to be any serious complications during the pregnancy or birth, which are often observed after the age of thirty. A healthy mother endures pregnancy more easily and has a better chance of giving birth to a healthy child. Especially if she takes the Best Prenatal Vitamins 2021.

After childbirth, a young body recovers more easily, the uterus contracts well, and the postpartum period goes by without problems.

It's better to give birth at 18 than have an abortion and never give birth. Unfortunately, today, due to many circumstances, many women postpone childbirth and have an abortion.