Background: Despite the high prevalence of depressive and anxiety disorders among women with threatened abortion (TA), there is scant evidence regarding the efficacy of psychotherapies for this group Objectives: This research aimed to assess the effectiveness, acceptability, and feasibility of specific internet-based cognitive behavioral therapy (iCBT-Specific) and unified protocol (iUP) for women with a TA. Methods: In this semi-experimental study (from April to October 2023), after the treatment content was prepared, a total of 80 pregnant women with TA, over 18 years of age, having a gestational age of 5 - 12 weeks, from a hospital and two private clinics, who were diagnosed with depressive and anxiety disorders based on the short structured diagnostic interview (Mini-International Neuropsychiatric Interview), were selected. The participants were divided into two groups, undergoing iUP or iCBT-specific psychotherapies. All participants completed the Brief Symptom Inventory (BSI-18) to measure the levels of depressive and anxiety symptoms. Following eight weeks of internet-based therapy, consisting of eight 50-minute sessions, they completed the BSI-18 again, along with the Client Satisfaction Questionnaire (CSQ-8) and the System Usability Scale (SUS). Statistical analysis was performed using SPSS version 22 software, and t-test, paired t-test, and ANCOVA tests were used. Results: Both the iUP and iCBT-Specific models demonstrated high acceptability, and the average feasibility of treatment was above average for both models. In terms of acceptability and feasibility of treatment for women with TA, neither model proved to be superior (all P > 0.05). Both iUP and iCBT-Specific models were effective in reducing depression and anxiety in these women (effect size for within groups were respectively Eta = 0.370, Eta = 0.536). Also, in terms of improving depression and anxiety, there was no significant difference in the effectiveness of iUP and iCBT-Specific treatments (respectively P = 0.146, Eta = 0.027 and P = 0.221, Eta = 0.019) Conclusions: The iUP treatment can be recognized as a reliable alternative to the iCBT-Specific method for alleviating depressive and anxiety symptoms in women with TA. Also, our results help gynecologists to use iUP as an alternative treatment when there is no definitive diagnosis of the type of disorder.