ETSEA – “ESPRiT Twins at School Entry Age”

The ETSEA study is a follow up to the ESPRiT study - a unique and important study into child health and well-being in Ireland that involved eight major maternity hospitals across the island of Ireland, and collected extensive data on the antenatal and perinatal growth and health of a cohort of twins born between 2007 and 2009.

The ETSEA study began in 2012 and is being carried out by researchers in the School of Public Health, Physiotherapy and Population Science in University College Dublin.  It is following the ESPRiT twins as they turn five years of age and start their first year of formal schooling.  For the ETSEA study, we are assessing the twins’ health, level of activity, how they get on with other children and adults, and their home and school environment.

Study Design

The ETSEA study is one of the first twin studies in the world that has prospectively measured prenatal development and in addition, followed up with assessments of early childhood development and environment. This design allows us to explore the role of the postnatal environment in the association between children’s prenatal and postnatal development.

Identifying factors that can influence development at this early age is particularly important as previous studies have shown a possible link between development of individuals at age 5 and their health status when fully grown.

Current Status

To date, almost 99% of mothers of same-sex twin pairs (n=496) have agreed to take part in at least one part of the study.  Data for the study are collected by a number of means:  Mothers complete a questionnaire for each twin at two different time points (the questionnaire ask about the child’s health, behaviour, sleeping and eating patterns); Researchers visit the twin's home to collect anthropometric data, measuring each child’s height, weight, head and waist circumference and finally, teachers answer questions about the child’s behaviour and wellbeing in the classroom setting.

The home visits takes place when the child is 5 years 4 months old (+/- 1 month).  As at March 2014, 85% of the home visits that were scheduled had been completed.  Home visits will continue until the end of the study in March 2015, when the last of the twin pairs turn 5 year 4 months of age.  In total, 96% of parents have consented to allow us to approach their children's school principal, 95% of whom have agreed to ask the teacher to participate.  Over 92% of teachers who have been approached have completed and returned online questionnaires.

We’d like to take this opportunity to thank everyone who has taken part in the ETSEA study to date!  We really appreciate your time and help in collecting these important data.

Dissemination of Research

It is hoped that initial analyses will begin in Autumn of 2014.

Any queries or requests for further details may be directed to:

Visit the ETSEA study website here.

Presentations and Posters 


Mental Health in Twins at School Entry Age - Effects of Prenatal & Early Childhood Environment. Perinatal Ireland Study Day:  A State of the Art Meeting on Multiple Pregnancy and Fetal growth Restriction  Rotunda Hospital, March 2014.

Monozygotic twins' discordance in birth weight and mental health at school entry: ETSEA Study Oral Presentation F. Cronin, UCD Health Sciences Centre: GP Study Day and Workshop, October 2013. 


Developing the Mini Zygosity Measure (MZM) for Twin Research. Poster Presentation, F. Cronin, Faculty of Public Health Medicine Winter Scientific Meeting, December 2013.  

Development of the Mini Zygosity Measure (MZM) for use in Twin Research. Poster Presentation, F.Cronin, L. Philpott & R.E. Tremblay, Psychological Society of Ireland Annual Conference, November 2013 (Winner of Student Poster Merit Award)

Monozygotic twins’ discordance in birth weight, and mental health at school entry: The ETSEA Study. Poster Presentation, F. Cronin, Psychological Society of Ireland Annual Conference, November 2013