Oral Iron in Pregnant Women: How Often to Take It and Its Side Effects and Tolerability (IRONFIT)

January 25, 2026 updated by: Bnai Zion Medical Center

Iron Supplementation Frequency and Tolerability in Pregnancy

The goal of this prospective observational study is to examine the frequency of gastrointestinal side effects associated with oral iron supplementation during pregnancy. The main question it aims to answer is:

Does intermittent oral iron supplementation result in fewer gastrointestinal side effects compared with daily supplementation in pregnant women? Pregnant women who are prescribed oral iron as part of their routine medical care will take ferrous sulfate on an alternate-day schedule for one week. If no significant gastrointestinal side effects are reported, they will then take ferrous sulfate daily for an additional week and will be followed for one month. Participants will be contacted by the study investigator to report gastrointestinal side effects, and routine blood tests will be used to assess changes in hemoglobin and iron stores.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

This prospective observational study will be conducted in pregnant women who are prescribed oral iron supplementation as part of their routine prenatal care. The study is designed to reflect standard clinical practice and does not introduce any investigational treatment or deviation from accepted management.

Following enrollment, participants will receive oral ferrous sulfate in accordance with common clinical recommendations. The study includes two sequential exposure periods: an initial alternate-day dosing phase followed by a daily dosing phase, provided that no significant gastrointestinal intolerance is reported during the first phase.

At baseline, relevant demographic and pregnancy-related information will be recorded, including maternal age and gestational age at initiation of iron therapy. Baseline laboratory values related to iron status (including hemoglobin and iron stores) will be documented if obtained as part of routine care.

Participants will be instructed to take oral iron according to the prescribed schedule and to continue their usual diet and prenatal care. No dietary restrictions will be imposed as part of the study. Information regarding timing of iron intake, concomitant food consumption (including dairy products), and adherence will be collected through participant self-report.

Participants will be contacted by the study investigator at predefined time points during the supplementation period. Structured interviews will be used to assess gastrointestinal side effects, including constipation, abdominal pain, nausea, vomiting, diarrhea, bloating, and heartburn. Participants will be asked whether symptoms are new, worsened, or unchanged compared with baseline.

At one month after initiation of iron supplementation, participants will undergo follow-up blood tests as part of routine clinical monitoring to assess hemoglobin concentration and iron stores.

Study Type

Observational

Enrollment (Estimated)

50

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Israel
      • Haifa, Israel
        • Bnai Zion Medical Center
        • Contact:
        • Principal Investigator:
          • Diana Shair Nakhleh, MD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Pregnant women attending our high-risk pregnancy clinics (in Bnai Zion medical center)

Description

Inclusion Criteria:

  • Pregnant women aged 18-50
  • Indication for oral iron treatment as determined by the treating physician, in accordance with standard clinical practice
  • Baseline iron store levels measured prior to initiation of oral iron therapy

Exclusion Criteria:

  • Women taking ferrous sulfate 80 mg Tardiferon
  • Gastrointestinal diseases such as colitis
  • Women who received intravenous iron during pregnancy
  • Women who received blood transfusions during pregnancy
  • Women with anemia due to causes other than iron deficiency
  • History of bariatric surgery
  • Allergy to ferrous sulfate

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Incidence of gastrointestinal side effects in response to iron intake
Time Frame: Over the first 2 weeks of supplementation, with structured follow-up at week 1 and week 2
Over the first 2 weeks of supplementation, with structured follow-up at week 1 and week 2

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Bnai Zion Medical Center

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

February 1, 2026

Primary Completion (Estimated)

May 1, 2026

Study Completion (Estimated)

June 1, 2026

Study Registration Dates

First Submitted

January 11, 2026

First Submitted That Met QC Criteria

January 11, 2026

First Posted (Actual)

January 21, 2026

Study Record Updates

Last Update Posted (Actual)

January 27, 2026

Last Update Submitted That Met QC Criteria

January 25, 2026

Last Verified

December 1, 2025

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • BNZ 013424

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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