Effectiveness of STOP-4P in Reducing Anxiety Among Pregnant Women Undergoing Amniocentesis: A Randomized Controlled Trial at Hung Vuong Hospital

Amniocentesis may cause short-term anxiety because pregnant women may worry about the procedure, possible pain or complications, fetal safety, and uncertainty about the test result. The waiting period before amniocentesis was chosen as the intervention window because these concerns are already present before the procedure. It also gives participants time to receive a brief psychological intervention with minimal disruption to routine clinical care.

At enrollment, participants in all three study groups are stratified according to the clinical indication for amniocentesis. Different diagnoses and indications may be associated with different levels of anxiety before the procedure. Stratification helps control these baseline differences and improves comparability among the groups within each stratum before the next group allocation steps.

The protocol also includes a non-randomized observational comparison group receiving routine care alone. This group is enrolled during separate prespecified study sessions. Including this group helps distinguish the added effect of STOP-4P from the effects of other study-related supportive activities and from routine care alone.

All participants are offered access to STOP-4P after the main post-procedure assessment has been completed. This delayed access allows participants who did not receive STOP-4P before amniocentesis to use it while waiting for the test result, without affecting the main study comparison.

Anxiety and well-being are not reassessed at the two-week follow-up because participants' emotional responses may be strongly influenced by the amniocentesis result, especially if the result is abnormal. The later follow-up therefore focuses on clinical information and the use of STOP-4P rather than on evaluating its main anxiety-reduction effect.