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PregnancyHITFLOWNCT04288479

Acute Effects of High Intensity Training in Pregnancy on Fetal Well-being and Blood Flow Distribution

A study testing Single high-intensity interval training session in people with Pregnancy, run by Norwegian University of Science and Technology at 1 site in Norway.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial summary

Pregnant women are recommended to be physically active ≥150 min/week, but <15% of Norwegian women attain this goal. Several well-designed studies on lifestyle interventions focusing primarily on exercise training in overweight/obese pregnant women have reported disappointing outcomes with regard to maternal glycemic… Read more about this study

Who is it for?
Ages 18 years and older, women only
Conditions the study is for
Pregnancy
What is being tested?
Single high-intensity interval training session
Could I receive a placebo?
No, everyone receives an active treatment
How many people
34 participants
Where
1 siteNorway
Study dates
23 Feb 2022to 23 Apr 2025
Phase
Interventional
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • Women only
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • pregnant, gestational week 22-36
  • singleton fetus
  • no known diseases
  • capable of cycling on an ergometer bike

Who cannot join

  • hypertension
  • gestational diabetes mellitus
  • any contraindication to exercise training

Trial locations and contacts

1 site in 1 country.

Norway1 site
  • Dept Circulation and Medical Imaging, EXCAR Exercise Lab

    Trondheim

Other trials in Norway

About this study

Official title: Acute Effects of HIT on Fetal Well-being and Blood Flow Distribution - a Pilot Study

Pregnant women are recommended to be physically active ≥150 min/week, but <15% of Norwegian women attain this goal. Several well-designed studies on lifestyle interventions focusing primarily on exercise training in overweight/obese pregnant women have reported disappointing outcomes with regard to maternal glycemic control, gestational weight gain and infant outcomes. Low adherence to the training program was found to be a problem; the participants did not enjoy the exercise program and had difficulties scheduling time to exercise. Pregnant women also report that they are not sure what exercises are safe during pregnancy.

High intensity interval training (HIT), defined as short periods of intense activity separated by low-intensity breaks, has proved to induce superior improvements in insulin sensitivity and fitness compared with continuous moderate intensity training in individuals at increased risk for cardiometabolic diseases. Even short-term (6 weeks) HIT with brief (15-60 sec) work-bouts and a total time commitment of <45 min per week, improves insulin sensitivity similar to that attained after 6 months of traditional endurance training.

Read more

HIT is feasible and enjoyable for individuals with low fitness level and with obesity.

HIT is therefore a highly potent intervention that elicits important changes in a range of clinically relevant health outcomes in reproductive-aged women.

This study will investigate fetal responses to a single bout of HIT. Preliminary data of the investigators suggest that HIT does not negatively influence fetal heart rate. Others have reported that uterine and umbilical blood flow are not changed during or following acute exercise. However, no previous study has determined the acute effect of HIT on uterine blood flow and there are no studies investigating the fetal blood flow distribution in response to exercise. Since the relative distribution of blood to the fetal liver is associated with newborn adiposity, fetal blood flow distribution in response to exercise can provide insight about the effect of maternal exercise on offspring health.

Conditions
Pregnancy
Being tested
Single high-intensity interval training session
Keywords
Exercise, High Intensity Interval Training, Pregnancy Outcome, Placental Circulation, Fetal Blood, Heart Rate, Fetal
Medical subject headings
Motor Activity

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • Single high-intensity interval training sessionBehavioural

    Also called HIT

    10 minutes warming up at low-to-moderate intensity, 8x30 seconds high intensity interval training with fetal heart rate measurement after each 30 second work-bout, 2 minutes recovery at low-to-moderate intensity. Continuous monitoring of maternal heart rate.

Study groups in NCT04288479
Study groupRoleWhat they receive
Doing a single HIT session in gestational week 22-36ExperimentalNot described
Receives: Behavioral: Single high-intensity interval training session

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. blood flow in fetal veins

    examined by Doppler ultrasound during 30 minutes

    Measured: 1 day

  2. blood flow in fetal arteries

    examined by Doppler ultrasound during 30 minutes

    Measured: 1 day

Secondary outcomes (7)
  1. maternal heart rate

    Measured: 1 dag

  2. Fetal heart rate

    Measured: 1 day

  3. Umbilical vein diameter

    Measured: 1 day

  4. Maternal systolic blood pressure

    Measured: 1 day

  5. Maternal diastolic blood pressure

    Measured: 1 day

  6. Maternal body weight

    Measured: 1 day

  7. Maternal height

    Measured: 1 day

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted28 Feb 2020
  2. Study start23 Feb 2022
  3. Primary completion23 Apr 2025
  4. Study completion23 Apr 2025

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase N/A
Primary purpose
Treatment
Allocation
Not applicable
Intervention model
Single group
Model description
before-after intervention effect measurement
Masking
None (open label)
Enrolment
34 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT04288479
Sponsor's protocol ID
62993
Acronym
HITFLOW
Status last verified
May 2025
First submitted
26 Feb 2020
Last updated
21 May 2025
Results posted
No
Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
No

Questions about this trial

What is this clinical trial studying?

A study testing Single high-intensity interval training session in people with Pregnancy, run by Norwegian University of Science and Technology at 1 site in Norway.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 4 inclusion and 3 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 21 May 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in Norway. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

blood flow in fetal veins (time frame: 1 day). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 21 May 2025.

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