Background This study aims to examine adult separation anxiety in pregnant women and its relationship with dysfunctional attitudes from the perspective of cognitive theory. Methods The sociodemographic data, Adult Separation Anxiety Questionnaire (ASA-27), and Dysfunctional Attitudes Scale-Revised (DAS-R) questionnaire were utilised to examine the correlation between sociodemographic factors and the ASA and dysfunctional attitudes in women attending antenatal obstetric clinics. Results The study included 190 pregnant women. Of these, 45.8% (n=87) had significant adult separation anxiety disorder (ASAD) symptoms. There was no significant difference between the ASAD (+) and ASAD (-) groups in terms of sociodemographic characteristics (p>0.05). However, a significant association was found between ASAD and the gestational period (p=0.02). DAS-R scores were higher in patients with ASAD symptoms (p<0.001). Positive correlations were observed between DAS-R and perfectionism or achievement and between DAS-R and the need for approval or dependency (p=0.001). DAS-R and gestational week showed potential as predictors of ASAD positivity (Area under the ROC curve (AUC)=0.725 vs. 0.632, respectively). Conclusion Pregnancy can be a sensitive period for the development of separation anxiety in adults. The development and treatment of separation anxiety in adults may benefit from cognitive-behavioural interventions that address dysfunctional attitudes during pregnancy.