Calculating length of gestation from the Society for Assisted Reproductive Technology Clinic Outcome Reporting System (SART CORS) database versus vital records may alter reported rates of prematurity.
OBJECTIVE
To compare length of gestation after assisted reproductive technology (ART) as calculated by three methods from the Society for Assisted Reproductive Technology Clinic Outcome Reporting System (SART CORS) and vital records (birth and fetal death) in the Massachusetts Pregnancy to Early Life Longitudinal Data System (PELL).


METHODS
Historical cohort study.


METHODS
Database linkage analysis.


METHODS
Live or stillborn deliveries.


METHODS
None.


METHODS
ART deliveries were linked to live birth or fetal death certificates. Length of gestation in 7,171 deliveries from fresh autologous ART cycles (2004-2008) was calculated and compared with that of SART CORS with the use of methods: M1 = outcome date - cycle start date; M2 = outcome date - transfer date + 17 days; and M3 = outcome date - transfer date + 14 days + day of transfer. Generalized estimating equation models were used to compare methods.


RESULTS
Singleton and multiple deliveries were included. Overall prematurity (delivery <37 weeks) varied by method of calculation: M1 29.1%; M2 25.6%; M3 25.2%; and PELL 27.2%. The SART methods, M1-M3, varied from those of PELL by ≥ 3 days in >45% of deliveries and by more than 1 week in >22% of deliveries. Each method differed from each other.


CONCLUSIONS
Estimates of preterm birth in ART vary depending on source of data and method of calculation. Some estimates may overestimate preterm birth rates for ART conceptions.
Department of Obstetrics and Gynecology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire. Electronic address: judy.e.stern@dartmouth.edu.
Judy E
JE
Stern
Mass-General Hospital for Children, Harvard Medical School, Boston, Massachusetts.
Milton
M
Kotelchuck
Department of Obstetrics, Gynecology, and Reproductive Biology, Michigan State University, East Lansing, Michigan.
Barbara
B
Luke
Department of Community Health Sciences, Boston University School of Public Health, Boston, Massachusetts.
Eugene
E
Declercq
Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts.
Howard
H
Cabral
Bureau of Family Health and Nutrition, Massachusetts Department of Public Health, Boston, Massachusetts.
Hafsatou
H
Diop
D000328:Adult; D015331:Cohort Studies; D016208:Databases, Factual / Q000639:trends; D005260:Female; D006801:Humans; D007234:Infant, Premature; D008137:Longitudinal Studies; D008875:Middle Aged; D011247:Pregnancy / Q000502:physiology; D018873:Pregnancy Rate / Q000639:trends; D047928:Premature Birth / Q000175:diagnosis* / Q000453:epidemiology; D027724:Reproductive Techniques, Assisted / Q000592:standards* / Q000639:trends; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
ART; Gestational age; PELL; SART CORS; prematurity