- Objective: evaluate prophylactic effects of synbiotic supplementation and psychobiotic diet on antenatal depression and pregnancy-related anxiety in women with GDM without baseline psychiatric disorders.
- Design: randomised, controlled three-arm parallel trial of 102 pregnant women, assigned 1:1:1 to synbiotic, psychobiotic diet or placebo from 28 weeks to four weeks postpartum.
- Outcomes and analysis: primary antenatal depression and pregnancy-related anxiety at 38 weeks; secondary postpartum measures, metabolic and neonatal outcomes; modified intention-to-treat and per-protocol analyses.
BMJ Open. 2026 Sep 16;16(9):e118047. doi: 10.1136/bmjopen-2026-118047.
ABSTRACT
BACKGROUND: Gestational diabetes mellitus (GDM) is one of the most prevalent metabolic disorders during pregnancy and may lead to various short-term and long-term complications for both the mother and the fetus. It is also associated with psychological disorders, such as anxiety and depression, the prevalence of which is reported to be two to four times higher than that among healthy pregnant women. Psychobiotics may improve cognitive and emotional function through modulation of the gut-brain axis. Therefore, this study was designed to evaluate the prophylactic effects of synbiotic supplementation and a psychobiotic diet during pregnancy in women with GDM who do not have clinically significant depressive symptoms or psychiatric disorders at baseline. The primary outcomes are antenatal depression and pregnancy-related anxiety at 38 weeks of gestation; secondary outcomes include postpartum depression and anxiety at 4-6 weeks after birth, maternal metabolic indices at 38 weeks of gestation and selected maternal and neonatal outcomes assessed immediately after birth.
METHODS AND ANALYSIS: This is a randomised, controlled, three-arm parallel trial. A total of 102 pregnant women diagnosed with GDM between 24 and 28 weeks of gestation will be randomly assigned (1:1:1) to one of three groups: a synbiotic capsule (Group 1), a psychobiotic diet (Group 2) and a placebo capsule (control group). Allocation will be performed using block randomisation, stratified by parity. Regardless of group assignment, all participants will receive a standardised healthy diet education session in accordance with the Iranian Ministry of Health protocols. The intervention will be administered from the time of GDM diagnosis (28 weeks of gestation) until 4 weeks postpartum. Outcomes will be assessed through maternal and neonatal medical records, laboratory analyses, the Edinburgh Postnatal Depression Scale, Revised Pregnancy-Related Anxiety Questionnaire, Postpartum Specific Anxiety Scale-Research Short Form and a 3 day dietary food record. Data analysis will be performed according to the modified intention-to-treat approach. Additionally, a per-protocol analysis will be conducted for participants with an adherence rate of ≥90%.
ETHICS AND DISSEMINATION: The study protocol has been approved by the Ethics Committee of Tabriz University of Medical Sciences (IR.TBZMED.RCE.1404.565). Findings will be disseminated through peer-reviewed journals and presentations at relevant scientific conferences.
TRIAL REGISTRATION: IRCT20220926056046N7.
PMID:42749371 | DOI:10.1136/bmjopen-2026-118047
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