Sawyer, Martha, of Josiah, [baptized] July 22, 1764.
↑Source:Pearce genealogy : being the record of the posterity of Richard Pearce, an early inhabitant of Portsmouth, in Rhode Island, who came from England, and whose genealogy, p. 53, suggests that the birth date is 1757. The imprecision indicates this is probably an estimate but no justification for the date or the resulting birth order is given (i.e., using the order named in a probate document, etc.) This source may have had some reason to come up with the birth order it presents, but it does not appear to have paid much attention to birth dates, and simply appears to have spaced the children out every 2 years. Thus, it puts Josiah, Jr. in 1755, even though there is a record of his birth in June 1756, so he would fall half way between Priscilla in 1753 (birth recorded Mar 1754) and Martha in 1757 (birth not recorded, baptism in 1764), continuing on with John in 1759, Sarah in 1761, and more.
July 1764 is only 9 months after Isaac's birth in Oct 1763, and Martha's birth does not fit well between Isaac and her baptism. This may suggest that her baptism could have been some years after her birth. But, at least part of 1757 is ruled out as a possible birth year, due to proximity to Josiah's birth June 1756, and may not be much more attractive as an alternative. Without evidence, choosing one or the other, or even coming up with a third possibility, seems arbitrary.