Melatonin in Pregnancy (MEL-P2)

May 4, 2026 updated by: University of Aberdeen

Investigation of Melatonin Production in Pregnancy: a Pilot Study to Define the Contribution of the Placenta

Melatonin is well known for its role in the sleep-wake cycle and is synthesised in response to low light levels from the pineal gland. In our previous study it was found that serum melatonin levels increased dramatically during pregnancy, such that levels were up to 100 fold higher in the third trimester compared to healthy non-pregnant women. The placenta contains the enzymes which are involved in synthesising melatonin but it is unclear if this is the source of the high levels in pregnancy. Severe pre-eclampsia has been reported to be associated with low levels of melatonin. In this study its is proposed to measure serum melatonin immediately before and after delivery and in cord blood and relate the levels to those in the placenta itself. This will contribute to the potential role for melatonin as a biomarker for obstetric disease and potentially as a therapeutic agent in future. This observational pilot study aims to measure serum and placental melatonin levels (as the major metabolite 6-hydroxymelatonin sulphate) in pregnant women undergoing elective Caesarean section.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

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

Background Melatonin, a substance produced by the pineal gland, is well known for its role in the sleep-wake cycle but it is less well known as an effective antioxidant. It is able to access all parts of the cell, and can cross the blood-brain and placental barrier.

Melatonin has been reported to be synthesised in the placenta and may have both receptor mediated and non-receptor mediated protective functions during pregnancy. Severe pre-eclampsia has been reported to be associated with low levels of melatonin in the placenta although it is not known if the placental melatonin contributes to circulating levels.1,2 Despite this, melatonin levels have been proposed as a biomarker of pre-eclampsia. More information on the role of melatonin and metabolism of melatonin in pregnancy would inform planning of larger research studies to investigate the potential role for melatonin as a bio-marker for obstetric disease and potentially as a therapeutic agent in future.

Melatonin is synthesized endogenously from serotonin via two steps; the first, rate limiting step is arylalkylamine N-acetyltransferase mediated acetylation of serotonin to N-acetyl serotonin. The second step is methylation of N-acetyl serotonin via the enzyme hydroxyindole O-methyltransferase (also called N-acetylserotonin O-methyl-transferase).3,4 Interrogation of our database of next generation sequencing analysis of 80 human foetal livers revealed that the genes encoding these enzymes were not present although those encoding related acetyltransferases were. We can conclude that the human foetal liver is not a site of melatonin synthesis.

Our previous work found melatonin levels do however increase markedly during pregnancy and are up to 50-100 times higher than non-pregnant women in the third trimester (Figure). The physiological role of these elevated melatonin levels remains a supposition and the relationship of melatonin levels in the placenta with the maternal and foetal circulations at different stages of pregnancy are unclear. Melatonin synthesizing enzymes have been found in human placental tissue, however it is not clear whether placental production of melatonin is directly related to the elevated circulating maternal melatonin levels.

The production of melatonin is catalysed by specific enzymes and although these enzymes have been found in placental tissue, it is not known if the high melatonin levels in pregnancy come from the placenta and what the role of this melatonin is. It is proposed to measure melatonin in placentas and maternal/cord blood from women undergoing planned Caesarean section. The results should enable defining as to whether the placenta is a major source of melatonin and how the pattern of production changes in pregnancy. The blood samples taken from women having a Caesarean section and the umbilical cord will provide information about the role of melatonin at delivery.

If melatonin levels in the maternal circulation falls after delivery and placental tissue melatonin levels are well above limits of detection, then a firm conclusion that the placenta is the source of elevated maternal melatonin would be justified. This observational pilot study aims to measure 6-hydroxymelatonin sulphate levels in blood from women undergoing Caesarean section and umbilical cords, and from placental tissue.

This is an observational pilot study to investigate 6-hydroxymelatonin sulphate levels in blood from pregnant women immediately before and after delivery, from umbilical cord blood at the time of delivery and in samples of placental tissue.

Healthy pregnant women will be recruited at the pre-Caesarean section pre-assessment clinic.

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 (Actual)

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.
15

Contacts and Locations

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

Study Locations

  • United Kingdom
    • If Already Stated Select NOT Listed
      • Aberdeen, If Already Stated Select NOT Listed, United Kingdom, AB25 2ZD
        • University of Aberdeen/NHS Grampian
    • Lowland Scotland
      • Ellon, Lowland Scotland, United Kingdom, AB25 2ZB
        • Aberdeen Maternity Hospital

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

16 years to 45 years (Child, Adult)

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Healthy pregnant women scheduled for elective Caesarean section

Description

Inclusion Criteria:

  • Scheduled for elective caesarian section
  • Singleton pregnancy
  • Aged 16-45
  • Taking no regular medication other than pregnancy related vitamins or supplements

Exclusion Criteria:

  • Pregnancy non-viable
  • Twins or higher multiple pregnancies
  • Outside age range
  • Diabetes or pre-existing hypertension, chronic kidney disease or autoimmune disorders

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

  • Observational Models: Case-Only
  • Time Perspectives: Prospective

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
Measure Description
Time Frame
6-hydroxymelatonin sulphate in serum
Time Frame: 24 hours after delivery
Change in serum 6-hydroxymelatonin sulphate levels after delivery
24 hours after delivery

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
6-hydroxymelatonin sulphate in serum
Time Frame: Immediately after delivery
Serum 6-hydroxymelatonin sulphate levels in umbilical cord blood after delivery
Immediately after delivery
6-hydroxymelatonin sulphate in placental tissue
Time Frame: Immediately after delivery
Serum 6-hydroxymelatonin sulphate levels in placental tissue after delivery
Immediately after delivery

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.
University of Aberdeen

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
NHS Grampian

Publications and helpful links

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Helpful Links

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 (Actual)

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.
June 6, 2018

Primary Completion (Actual)

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.
August 31, 2018

Study Completion (Actual)

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.
March 30, 2019

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).
July 10, 2018

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.
July 31, 2018

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.
August 1, 2018

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.
May 8, 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.
May 4, 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.
February 1, 2021

More Information

Terms related to this study

Additional Relevant MeSH Terms

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.
  • 2-020-18

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

IPD Plan Description

Reasonable requests for access to anonymous IPD (biochemical data) will be considered

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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