Not to be snippy, but if the answer was easy, I wouldn't have asked it here. I haven't found a birth record for the Priscilla born in 1717. The only birth record I've seen for a Priscilla born to Nathaniel and Deborah Patten is for the child born in 1713, who died in 1714.
It's tempting to attach my Priscilla to Nathaniel; it was common then for parents to name the next child of the same sex after a child who died, so that part would fit. The problem is that my Priscilla was born when Nathaniel was between wives. Deborah died in 1716 and my Priscilla was born in 1717. Even that wouldn't matter, though, if I could find a birth record, because the calendar shift means a record can be off by one year. It could be that Deborah died soon after giving birth to Priscilla.
What I was hoping to find, failing a birth record, was a mention of her in one of the many genealogies written about these early families.