The Aim of This Study is to Gain Insight Into the Occurrence of Irritable Bowel Symptoms During Ovarian Stimulation in Individuals With PCOS and in Women Who Wish to Freeze Their Eggs. This Study Uses Questionnaires. (FIBS)

Fertility Treatment: Impact on Symptoms of Irritable Bowel Syndrome

This exploratory study investigates the impact of fertility treatments on symptoms of irritable bowel syndrome (IBS) in women. Specifically, the study focuses on two groups:

• Women with polycystic ovary syndrome (PCOS) who are starting their first IVF cycle.
• Women who choose social freezing (freezing eggs for social reasons).

Background and Rationale PCOS is an endocrine disorder with hormonal and metabolic abnormalities associated with reduced fertility. There are four PCOS phenotypes, of which phenotypes A and B are the "classic" forms. Social freezing is becoming increasingly popular as an option for women without a partner who want to preserve their fertility.

IBS is a common gastrointestinal disorder involving motility disorders and a disturbed gut-brain axis. There is an increased risk of anxiety and depression in IBS patients. Women with PCOS have a twofold increased risk of developing IBS. However, little is known about the effect of hormonal fertility treatments on IBS symptoms.

Objectives

• Primary objective: To investigate whether fertility treatments influence the prevalence and severity of IBS symptoms.
• Secondary objective: To investigate this change in IBS prevalence and severity in relation to:
• Changes in anxiety and depression scores.
• Changes in general gastrointestinal complaints.
• Subgroup analyses based on:
• Type of stimulation
• Duration of desire to have children
• Ethnicity
• PCOS type
• Hormonal and ultrasound response

Study design The study is a prospective, interventional exploratory study in which participants complete questionnaires before and after the hormonal stimulation phase.

• Start date : March 1, 2026
• End date of data collection: February 2027
• Participation locations: Fertility Clinic UZ Brussels
• Target sample size: 120 women (60 per group)

Data collected

Before treatment:

• Demographics (height, weight, ethnicity)
• Medical history related to fertility
• PCOS phenotype (in study arm)

After treatment:

• Hormonal values (FSH, LH, estrogen, progesterone)
• Number of follicles on ultrasound
• Number of eggs collected

Questionnaires:

• IBS-SSS (IBS symptom severity)
• Rome IV and III criteria (IBS diagnosis)
• GSRS (general GI symptoms)
• PHQ-9 (depression)
• GAD-7 (anxiety)

Measuring instruments

• Rome IV and III criteria: Diagnosis of IBS based on frequency and nature of abdominal pain and changes in bowel movements.
• IBS-SSS: Five dimensions of IBS symptoms, score between 0 and 500.
• GSRS: General gastrointestinal complaints in five domains.
• PHQ-9 and GAD-7: Validation instruments for depression and anxiety.

Data management

• Data is collected manually using paper questionnaires.
• Data is then entered into RedCap.
• Analysis is performed using SPSS.
• Strict compliance with GDPR and confidentiality guidelines.

Statistical Analysis

• Logistic regression: To determine the likelihood of meeting the Rome criteria before and after treatment.
• Multiple linear regression: To identify factors that influence change in IBS-SSS scores.
• Model selection: Based on AIC (Akaike Information Criterion).
• Separate analyses for PCOS and social freezing groups.

Study Overview

• Status: Not yet recruiting
• Conditions: PCOS (Polycystic Ovary Syndrome)
• Intervention / Treatment: Other: questionnaires

• Study Type: Interventional
• Enrollment (Estimated): 120
• Phase: Not Applicable

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Diagnosis of PCOS according to the 2004 Rotterdam criteria (only for the PCOS group and not for the social freezing group)
• Initiating their first cycle of IVF treatment (PPOS and freeze only protocol)
• Nulliparous
• ≥ 18 years
• Willing to participate in the study
• Understanding Dutch, French or English

Exclusion Criteria:

• - Known inflammatory bowel disorder
• Known major intestinal bowel disorder
• Known systemic or auto-immune disorder with implication for the GI system
• History of abdominal surgery (appendectomy and cholecystectomy allowed if >6 months earlier)
• History of gastro-enteritis in the past 6 weeks

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: PCOS group; Women with PCOS fill in questionnaires before ovarian stimulation and after.	Other: questionnaires; Questionnaires: Rome III and IV criteria, GSRS, IBS-SSS, PHQ-9 and GAD-7
Experimental: Social freezing group; Women who want to freeze their eggs fill in the questionnaires before and after ovarian stimulation.	Other: questionnaires; Questionnaires: Rome III and IV criteria, GSRS, IBS-SSS, PHQ-9 and GAD-7

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proportion of participants meeting IBS diagnostic criteria before and after ovarian stimulation	Assessed using Rome III and Rome IV criteria. The number of participants meeting IBS diagnostic criteria will be compared before (at consultation) and after (at oocyte retrieval) ovarian stimulation.	"From start of ovarian stimulation to oocyte retrieval, up to 14 days"
Change in IBS symptom severity before and after ovarian stimulation	Assessed using the IBS Severity Scoring System (IBS-SSS), a validated 5-item questionnaire. Total scores range from 0 to 500, with categories: remission (<75), mild (75-175), moderate (175-300), and severe (>300). The total IBS-SSS score will be compared before (at consultation) and after (at oocyte retrieval) ovarian stimulation.	From start of ovarian stimulation to oocyte retrieval, up to 14 days"

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in general gastrointestinal symptom severity before and after ovarian stimulation	"Assessed using the Gastrointestinal Symptom Rating Scale (GSRS), a validated 15-item questionnaire scored on a 7-point Likert scale. The total GSRS score will be compared before (at consultation) and after (at oocyte retrieval) ovarian stimulation."	From start of ovarian stimulation to oocyte retrieval, up to 14 days"
Change in depression levels before and after ovarian stimulation	Assessed using the Patient Health Questionnaire (PHQ-9), a validated 9-item questionnaire. Total scores range from 0 to 27."	From start of ovarian stimulation to oocyte retrieval, up to 14 days
Change in anxiety levels before and after ovarian stimulation	Assessed using the Generalized Anxiety Disorder scale (GAD-7), a validated 7-item questionnaire. Total scores range from 0 to 21."	From start of ovarian stimulation to oocyte retrieval, up to 14 days

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Association between clinical and demographic factors and IBS symptom severity	Subgroup analyses will be performed to assess differences in IBS symptom severity (IBS-SSS and GSRS) based on: type of ovarian stimulation protocol, number of prior fertility treatments, duration of infertility, ethnicity, PCOS subtype, hormonal profile during controlled ovarian stimulation (estradiol, progesterone, LH, FSH), and ultrasound findings	From start of ovarian stimulation to oocyte retrieval, up to 14 days

Collaborators and Investigators

• Sponsor: Universitair Ziekenhuis Brussel

Study record dates

Study Major Dates

• Study Start (Estimated): April 20, 2026
• Primary Completion (Estimated): March 1, 2027
• Study Completion (Estimated): May 1, 2027

Study Registration Dates

• First Submitted: March 6, 2026
• First Submitted That Met QC Criteria: April 13, 2026
• First Posted (Actual): April 16, 2026

Study Record Updates

• Last Update Posted (Actual): April 16, 2026
• Last Update Submitted That Met QC Criteria: April 13, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Urogenital Diseases; Genital Diseases; Endocrine System Diseases; Neoplasms; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Genital Diseases, Female; Ovarian Diseases; Adnexal Diseases; Gonadal Disorders; Ovarian Cysts; Cysts; Polycystic Ovary Syndrome; Health Care Quality, Access, and Evaluation; Investigative Techniques; Epidemiologic Methods; Data Collection; Health Care Evaluation Mechanisms; Quality of Health Care; Public Health; Environment and Public Health; Surveys and Questionnaires
• Other Study ID Numbers: 1432025000254

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No