Agreement between maternal interview- and medical record-based gestational age.

Agreement between maternal interview- and medical record-based gestational age was assessed by using data from a case-control study of childhood strabismus. The sample consisted of 383 cases of strabismus and their age-matched controls, diagnosed between 1985 and 1986 in Baltimore, Maryland, who were under age 7 years when diagnosed. Medical record-based gestational age was derived, in order of priority, from early ultrasound examination, time from the last menstrual period, pediatric examination, and obstetric examination. The intraclass correlation coefficient, kappa, and mean difference were used to compare agreement between maternal interview- and medical record-based gestational age by maternal and pregnancy characteristics and characteristics related to study design. Overall, 86 percent of mothers were within 2 weeks of the gestational age reported in the medical record. The intraclass correlation coefficient comparing maternal and medical record-based gestational age was 0.83 (95% confidence interval 0.80-0.86). Agreement was positively associated with shorter length of recall, low birth order, and having a neonatal illness related to prematurity. Agreement was poor among mothers of healthy preterm infants. There was a weak positive association between recall and some sociodemographic covariates. There was greater misclassification of prematurity in the controls than in the cases. The results suggest that, in general, women recall gestational age well, which supports the use of gestational age derived from maternal interviews.