Probabilistic linkage of assisted reproductive technology information with vital records, Massachusetts 1997-2000.

To assess the validity of probabilistic linkage (PL) in combining national surveillance data on assisted reproductive technology (ART) with Massachusetts birth and infant death data, for the purpose of monitoring maternal and child health outcomes of ART. A study conducted in 2006 utilized direct identifiers to match Massachusetts birth records with records on ART procedures performed to Massachusetts residents in fertility clinics located in Massachusetts and Rhode Island, achieving a linkage rate of 87.5%. The present study employed PL using the program Link Plus, without access to direct identifiers. The primary linking variables were maternal and infant dates of birth, and plurality. Ancillary variables such as maternal ZIP code and gravidity helped resolve duplicate matches and capture additional matches. PL linked 5,390 (87.8%) of 6,139 deliveries, correctly identifying 96.4% of the matches previously obtained using deterministic linkage methods. PL yielded a high linkage rate with satisfactory validity; this method may be applied in other states to help monitor the maternal and child health outcomes of ART.