Comparison of birth certificates and hospital-based birth data on pregnancy complications in Los Angeles and Orange County, California

Table 1 Matching rates based on different matching criteria

						Number	Percentage based on Memorial Care data	Percentage based on birth certificate data
Matched records						62200	85.79 %	86.98 %
		Matching Variables
	Types of matching	DOB of child	Delivery hospital	DOB of mother	Mother’s name
1. Exact match on four variables		Exact	Exact	Exact	Exact	59105	81.52 %	82.65 %
2. Exact match on three variables		Exact	Exact	Partial^a	Exact	2869	3.96 %	4.01 %
3. Exact match on three variables		Exact	Exact	Exact	Partial^b	120	0.17 %	0.17 %
4. Exact match on two variables		Exact	Exact	Partial^a	Partial^b	106	0.15 %	0.15 %
Unmatched records in Memorial Care data with non-missing matching variables						4162	5.74 %
Unmatched records in Memorial Care data with missing matching variables						6138	8.47 %
Unmatched records in birth certificate data						9312		13.02 %

^amatched by any two of the three fields: year, month, and day
^bmatched by the first three characters in both the first name and the last name of the mother

ISSN: 1471-2393