White-Coat Hypertension in Early Pregnancy and Risk of Hypertensive Disorders: Consistency Across Blood Pressure Phenotyping Strategies

Background White-coat hypertension in pregnancy has been associated with adverse maternal and perinatal outcomes in recent meta-analyses, but substantial heterogeneity in diagnostic criteria limits interpretation. Whether this association is consistent across different blood pressure phenotyping strategies remains unknown. Methods We conducted a retrospective cohort study of 320 pregnant women evaluated before 20 weeks in a specialized hypertension-pregnancy clinic. Blood pressure phenotypes were defined under three classification models of increasing complexity, from home monitoring alone to complete ambulatory monitoring. Women on antihypertensive treatment before 20 weeks were classified as sustained hypertension regardless of measured values. Agreement between models was assessed by Cohen’s kappa; multivariable models were adjusted for maternal age, body mass index, parity, previous hypertensive disorders and aspirin use. Results White-coat hypertension was consistently associated with higher odds of hypertensive disorders of pregnancy across all models (adjusted odds ratio 2.08–2.23; 95% CI 1.01–4.93). Whole-cohort agreement between models was high (kappa 0.878–0.943) but fell to 0.729–0.881 among the 194 untreated women, of whom 24 (12.4%) were reclassified between Models 1 and 3. No association was detected between white-coat hypertension and adverse fetal outcomes (odds ratio 0.74–1.00 across models), although events were few in either group. Conclusions White-coat hypertension diagnosed before 20 weeks is consistently associated with an increased risk of hypertensive disorders of pregnancy, regardless of the classification strategy used. Home blood pressure monitoring is therefore a reasonable first-line tool for phenotyping in early pregnancy, although among untreated women the choice of strategy relabels about one in eight.