Condition category
Circulatory System
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting
Publication status

Plain English Summary

Background and study aims
Heart rate variability reflects the responsiveness of the autonomic nervous system to environmental factors. In a stressful environment, the sympathetic nervous system dominates, reducing the heart rate variability. Lower heart rate variability is a risk factor for unfavorable outcomes of various diseases, a longer recovery, and sudden heart death in newborns. The aim of this study is to determine whether a newborn’s sleeping position affects their heart rate variability.

Who can participate?
Healthy newborns aged 1 to 28 days after birth

What does the study involve?
While the newborns sleep, the researchers measure heart rate variability in four sleeping positions, namely supine without and with tilt, and prone with and without tilt. At the same time they measure blood oxygen levels, heart and breathing rates, blood pressure and body temperature, and assess alertness.

What are the possible benefits and risks of participating?
The benefit of participating is the analysis of the newborn’s heart rhythm. If there are heart rhythm problems the researchers consult a pediatric cardiologist. There are no risks of participating.

Where is the study run from?
University Medical Centre Ljubljana (Slovenia)

When is the study starting and how long is it expected to run for?
September 2016 to September 2018

Who is funding the study?
University Medical Centre Ljubljana (Slovenia)

Who is the main contact?
Prof. Matjaž Klemenc

Trial website

Contact information



Primary contact

Prof Matjaž Klemenc


Contact details

Klementa Juga 16
+38 (0)653301141

Additional identifiers

EudraCT number

2020-000701-88 number

Nil known

Protocol/serial number

Nil known

Study information

Scientific title

The effect of sleeping position on heart rate variability in newborns


Study hypothesis

It is hypothesized that the parameters of heart rate variability might be more favorable for outcome in the supine position compared to prone, even more so with tilt.

Ethics approval

Approved 20/09/2016, National Ethics Committee of Slovenia (Štefanova ulica 5, 1000 Ljubljana, Slovenia; +386 (0)1 478 60 01;, ref: 0120-458/2016-3 KME 67/09/16

Study design

Cross-sectional cohort study

Primary study design


Secondary study design

Cross sectional study

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details to request a participant information sheet (


Cardiovascular and respiratory stable newborns who had no respiratory and/or haemodynamic support


After feeding, sleeping newborns were placed in a supine position with a 30˚head-up tilt of the bed for 30 min. ECG signals were recorded in four positions: the supine without and with tilt and prone with and without tilt by using an ECG Holter system (Vision 5L, Burdick, USA). Parameters were recorded in every position for at least 30 minutes, when the newborn was sleeping quietly. Simultaneously, the newborn’s alertness was assessed using a five-stage description. In all positions, the breathing frequency (BF) was counted (by visualizing the excursions of the thorax) and heart rate (HR) and blood oxygenation were measured by pulse oximeter (Intelli Vue MP 50, Philips, Germany) 10 min after changing the lying position of the newborn. Blood pressure (systolic and diastolic) was measured noninvasively using an inflatable cuff. Body temperature was measured by infrared non-contact frontal thermometer Veratemp + (Veratemp; USA).

Intervention type



Drug names

Primary outcome measure

Heart rate variability (HRV) measured by pulse oximeter for at least 30 minutes when the newborn was sleeping quietly in four positions

Secondary outcome measures

Parameters recorded in every position for at least 30 minutes, when the newborn was sleeping quietly:
1. Blood oxygenation measured using a pulse oximeter
2. Breathing frequency (BF) counted by visualizing the excursions of the thorax
3. Mean arterial blood pressure (MAP) measured using an inflatable cuff

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Stable cardiovascular and respiratory systems
2. No respiratory and/or hemodynamic support

Participant type

Healthy volunteer

Age group




Target number of participants


Total final enrolment


Participant exclusion criteria

1. Hypoxic ischemic encephalopathy (HIE)
2. Preterm birth
3. Infection
4. Neurological or congenital abnormalities

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

University Medical Centre Ljubljana
Neonatal Department of the Division of Paediatrics Bohoričeva ulica 20

Sponsor information


Ljubljana University Medical Centre

Sponsor details

Neonatal Department of the Division of Paediatrics
Bohoričeva ulica 20
+38 (0)65522 37 00

Sponsor type

Hospital/treatment centre



Funder type

Hospital/treatment centre

Funder name

University Medical Centre Ljubljana

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Results expected to be published in BMC Pediatrics.

IPD sharing statement
The datasets generated during and/or analysed during the current study are/will be available upon request from Matjaž Klemenc ( Raw data (ECG recordings) will become available from 01/05/2020 for the next 5 years. Access criteria: research in the field of heart rate variability in neonates, statistical analyses, data are anonymised, no ethical or legal restrictions.

Intention to publish date


Participant level data

Available on request

Basic results (scientific)

Publication list

2020 results in (added 23/10/2020)

Publication citations

Additional files

Editorial Notes

23/10/2020: The following changes were made to the trial record: 1. Publication reference added. 2. The total final enrolment was added. 13/03/2020: Trial's existence confirmed by National Ethics Committee of Slovenia.