Car accident at 15 weeks

So yesterday I was in a bad car accident I’m 15 weeks so I went to the ER they took a look and baby’s heart rate was at 149 BPM. But they informed me that my placenta lays low and they put me on miscarriage precautions. Any recommendations on what else I can do to make sure my bean stays in my belly for another 21 weeks? Any super foods?