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

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

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

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
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 Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

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

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
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

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
February 1, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
May 1, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
June 1, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
January 11, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 11, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
January 21, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
January 27, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 25, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
December 1, 2025

More Information

Terms related to this study

Keywords

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant 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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