P17 shot thoughts?

Ok I’m 12 weeks and I had a talk with my doctor today advice at 16 weeks starting p17 shots to help prevent prevent preterm labor. The only reason why my doctor wants me to consider it is because my last child I had three years ago was born premature at 32 weeks. My other two pregnancy before that were fine though and he thinks I may have had complications with preterm labor with my son because I had just had my daughter a year before like literally her birthday is May 18 2009 his birthday is May 11 2010 they are that close to each other in age. So I got a few weeks to decide if I want to take this shot every week for 20 weeks. Anyone else have these shots in the past or know anyone who has? What was your experience and does it really help? Thanks for any info I appreciate it.