RESUMEN
INTRODUCTION@#Expectant mothers may appear anxious even during healthy pregnancies. Unfortunately, little is known about antenatal anxiety, and affected women may remain undetected and untreated. This study aimed to examine the prevalence, incidence, course and associations of high state anxiety in routine obstetric care.@*MATERIALS AND METHODS@#This was an observational prospective cohort study at a large maternity unit. Obstetric outpatients with low-risk singleton pregnancies were recruited during first trimester consultations. Participants provided sociodemographic data and completed the State-Trait Anxiety Inventory (STAI) and Edinburgh Postnatal Depression Scale. The STAI was re-administered at each subsequent trimester.@*RESULTS@#Prevalence and incidence of high state anxiety among 634 completers were 29.5% (95% CI 25.6%-33.6%) and 13.9% (95% CI 9.9%-18.0%), respectively. Anxiety was persistent in 17.0% (95% CI 14.3%-20.2%) and transient in 26.3% (95% CI 23.1%-29.9%). Only persistently anxious participants had high mean second trimester state anxiety scores. Odds for anxiety of greater persistence increased by 29% (95% CI 24%-35%) per 1-point increase in first trimester depression scores, and decreased by 36% (95% CI 7%-56%) with tertiary education.@*CONCLUSION@#Antenatal anxiety symptoms are common even in normal pregnancies, especially among women with depression and lower education. Our study indicates value in exploring diagnostic criteria and quantitative measures for antenatal anxiety.