Thoughts on Makena?

I had my first baby on October 28th and her due date was December 4th, 34 weeks and 5 days. My water broke that morning and then she was here healthy and strong. since she was early, she had to be in the nicu to get her eating right before sending her home. no complications the whole pregnancy, labor was a smooth natural 5 hours and she didnt have any major complications. i definitely want to have more kids, but my doctor said to look into the makena shot to possibly keep from another preterm. What are your thoughts?