How do I convince my 16yr old pregnant Niece to breastfeed?

You don't. If you start badgering a 16 year old that she should breastfeed, you have any chance of her refusing to even hear about breastfeeding because she feels cornered. And it is fundamentally her choice anyway. She may be only 16, but SHE is going to be a parent.

You can ask if knows whether she wants to breastfeed, and you can offer to help her find information about her choice. That's where your involvement in this decision ends.

You can't convince her, but you can ask her view on the matter and discuss some resources with her if she is not certain. Often education is helpful if lack of knowledge is the issue. However, if she has some strong feeling about not breast feeding, you are not likely to change her mind.

In reality, the best you can do is discuss with her the reasons that she has for NOT wanting to breast-feed. If you can properly address her concerns as to why she doesn't want to breast-feed, then you may be able to convince her to breast-feed, at least for a little while. Ultimately, though, the decision is up to her.

Not your place to try and force her to breastfeed. Not everyone likes to breastfeed their kid, it's a personal choice

You don't. It's her choice. You can certainly discuss the research with her, and allowed her to make an informed choice, but you can't force her into your views.

Just found out the hospital will go over everything with her then she'll make her own decision.

You get yourself informed, then explain what you have learned to her. The final decision is hers. You could also talk to a lactation consultant, with her, to go over the pros and cons of breastfeeding versus using formula.

I have an 11 day old and still sore from Breast feeding if not want to do that why not ask her if she wants to pump? Less painful but still get breast milk from doing it.

You don't. As it is her choice, and her choice alone. She is the mother to that baby, and whatever decision she chooses to make, should be followed with support. Not criticism.

You dont. Its her child and her decision. Feeding Formula is not the WORST thing a parent can do to their child in the 18 years theyre responsible for them.