This is not a Birth Certificate but I note that Find A Grave via FamilySearch says:
Name: Emilie Clement Iznaga Maiden Name: Event Type: Burial Event Date: 1944 Event Place: Bronx, Bronx, New York, United States of America Photograph Included: Yes Birth Date: 30 Apr 1864 Death Date: 01 Nov 1944 Affiliate Record Identifier: 112422133 Cemetery: Woodlawn Cemetery
Citing this Record: "Find A Grave Index," index, FamilySearch (https://familysearch.org/pal:/MM9.1.1/QVG7-C7SS : accessed 20 March 2015), Emilie Clement Iznaga, 1944; Burial, Bronx, Bronx, New York, United States of America, Woodlawn Cemetery; citing record ID 112422133, Find a Grave, http://www.findagrave.com.
The birth date of 30 Apr 1864 is consistent with a number of immigration and passport records at FamilySearch which provide birth dates for Emilie Yznaga of:
- 1864 once
- 30 Apr 1864 twice
- 31 Oct 1864 four times
- 1865 once (spelled Emilia Yznaga)
It may or may not apply, but I suspect that relatives in their grief may struggle to remember a date when providing information for a death certificate at short notice, and have much more time to get it right when ordering a gravestone.