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The Peri/Postnatal Epigenetic Twins Study (PETS)

PETS is a research project being conducted by the Murdoch Children's Research Institute at The Royal Children's Hospital, Melbourne.

PETS is a study of twins, from when they were in the womb through to childhood and beyond. We aim to work out what makes us all who we are; our health, development and wellbeing. We have chosen to start our research with twins, who share the same mother, but are usually in their own 'sac' during pregnancy, then share the same home environment as children. Despite this, even 'identical' twins can have different personalities, physical characteristics and illnesses. We want to know why these differences exist and what they can tell us about the first years of life.

It would be of great value to us if you have any suggestions or comments you would like to make about our research and what research questions interests you. Your comments could even inspire us to research something we hadn’t previously thought of.

Some general information about the PETS study: 

There were 244 mothers of twin pairs who were recruited before their twins were born. Of these, 208 families agreed to participate again as their twin children reached six years of age. This is a remarkable 87% and a credit to all our families for the time and effort that is put into this research. In addition to this, we also had some families who were unable to participate in this phase of the study due to work and family commitments, but who would like to continue in the study. We look forward to being able to discover more about the health and development of twins in these families in the future.

We are thrilled to report that more than 90% of our participating families completed all three questionnaires about their twins’ health and development, dietary habits and preferences, their oral health and their families. Again, the time and effort that goes into responding to these questionnaires is very much appreciated. The information you are able to provide helps us to know more about twins, their families and to better understand any findings in the biological samples you provide. It also assists us to track the children from birth. 

Access to birth records 

We are currently contacting all our families to ask whether we can access the hospital records about the birth of the twins. Some of you will have already received this request. We hope to be able to collect information from these records from as many families as possible. This is because since you were recruited to the project, our understanding of how early life can predict future health and disease has improved. It is now clear that we could gain a much better insight if we could clarify some of the information collected from you during your pregnancy and the delivery of your twins. To ensure the information collected is accurate, we would like to access the pregnancy and birth medical records for you and your twins. In some cases, we will be seeking to confirm information already collected from you through questionnaires. In others, we will be seeking information about new factors that we did not ask previously that are related to those we have already collected. An example of how this information could be used is to learn more about:

  • developmental anomalies of the teeth
  • the relationship between genes, the environment in the womb, and tooth decay
  • whether there are early predictors of autism
  • the relationship between growth in the womb and later body weight
  • the relationship between growth in infancy and blood pressure at age six.

And as with all our previous study waves, your consent is optional.

For more information on PETS, who we are what we have found, please see our PETS poster.

Visiting academics

Dr Heide Temples from the US has returned to spend two months with our team. She analysed some of the samples and information collected when your twins were 18 months old. Heide was interested to discover more about the relationship between breastfeeding and the growth of your children. She found that breastfeeding for four to six months appeared to protect against the risk of obesity. The body mass index (BMI) and the size of infants’ bellies and arms were in a healthier range when the infants were breastfed longer (four to six months) Heide’s interest has continued and she is now looking at the measures that were collected as the twins turned six, to see if breastfeeding has a lasting effect on body weight. This research is valuable, because we already know that breastfeeding can be hard (especially when there are two babies to feed) and we hope that these findings will lead to better ways to support for mothers who would like to breastfeed.