Frank AS, et al. - Using data from the Norwegian Mother and Child Cohort Study (MoBa), a prospective population-based cohort study, researchers evaluated the agreement between self-reporting and thyroid hormone replacement therapy (THRT) prescription records before and during pregnancy and used a group-based trajectory model (GBTM) approach for women with similar THRT prescription patterns in longitudinal trajectory groups from 6 months before 12 months after pregnancy. During the early pregnancy period, the agreement between self-reporting and prescription records was high. Based on the results of the GBTM, approximately one in two women with hypothyroidism had adequate adherence to prescribed THRT throughout pregnancy. In view of the possible consequences, evidence of low adherence is of concern in 5.8% of pregnant women with hypothyroidism.