Evaluation of L-Arginine Supplementation on the Improvement of Uterine Artery Pulsatility Index in Color Doppler Ultrasound in Pregnant Women with Increased Uterine Artery Resistance

Investigating the Effect of L-Arginine Supplementation on Improving Uterine Artery PI in Color Doppler Ultrasound in Pregnant Women with Increased Uterine Artery Resistance

A double-blind parallel-group controlled clinical trial involving 70 patients.

In this study, participants at Arak University of Medical Sciences are randomly allocated into two groups, intervention and control, using block randomization with blocks of size 4. Random selection of blocks and assignment patterns within each block are performed using the Sealed Envelope software to ensure allocation concealment, preventing predictability of participant assignment to groups.

Pregnant women aged 18 to 50 years with increased uterine artery resistance, willing to participate in the study and without drug allergies to L-arginine.

Intervention Group: Participants in this group will receive daily treatment consisting of 80 mg aspirin, 1000 mg L-arginine capsules (Carn Double Strength) twice daily, and one 500 mg L-arginine capsule (Carn) once daily, totaling 2500 mg of L-arginine per day, starting from the diagnosis of increased uterine artery resistance (between weeks 12 to 24) for a duration of 6 weeks. Control Group: Participants in this group will only receive daily treatment with 80 mg aspirin.

Pulsatility Index (PI) of the uterine artery; Resistance Index (RI) of the uterine artery; Birth weight of the newborn; Apgar score at birth (at the first and fifth minute); Gestational age at delivery; Occurrence of preeclampsia; Intrauterine growth restriction (IUGR)

Participants will be allocated into two intervention and control groups in the order of entry, based on a randomization sequence that will be generated in advance. This sequence is unpredictable and the arrangement is entirely random. Sample allocation will utilize a random block size of 4 using block randomization software. Initially, all possible combinations of A and B within the 4-block will be generated. Subsequently, one block will be randomly selected and its allocation pattern will be used for participant assignment. This selected block will then be placed in the main container and another block will be chosen repeatedly. All these procedures will be conducted using software called Sealed Envelope. This method ensures concealment, meaning the allocation of individuals to groups will be unpredictable. The researcher will not be able to predict which group the next participant will be assigned to.

This study will be conducted as a double-blind trial to ensure patient blinding. Initially, in the control group, capsules similar in appearance to the intervention capsules (matched in color and size) will be prepared and administered to participants. Additionally, in the intervention group, placebo tablets made from starch will be given, resembling the control capsules. Therefore, none of the participants will be aware of which group they are assigned to or which medications are being administered. The medications will be prepared and placed in containers by the respected supervisor (primary advisor), and these containers will be handed over to the respective assistant. Consequently, the obstetrics and gynecology assistant involved in the thesis will not have any knowledge of the type of medications inside the containers and will not know the grouping of the patients. Thus, blinding of the researcher is maintained throughout the study.