A MAJOR difference in the birth weight of twins increases the risk of health problems for both babies, new research has revealed.
The study looked at 1,001 women who gave birth to twins between 2007 and 2009 in Irish maternity hospitals and units.
It found that a difference in birth weight of 18pc or more was linked to a higher health risk for both babies, including foetal or neonatal death, bowel complications, breathing difficulties, infection and admission to a neonatal intensive care unit.
While overall there was a very low rate of serious illness or death among the twins who were looked at in the study, the difference in birth weight had an impact.
The research found that twins who shared a single placenta were found to be at the highest risk and the larger baby had an equal chance of illness.
The research was led by Dr Fionnuala Breathnach, consultant obstetrician at the Rotunda Hospital in Dublin and a senior lecturer at the Royal College of Surgeons in Ireland.
"The 18pc cut-off point represents that threshold, above which risk increases for both babies. We tend to think of the smaller twin as being the more vulnerable one. Yet our study demonstrates that the large twin of a discordant pair is equally at risk.
"Recognition of this threshold difference in weight during pregnancy should trigger closer foetal monitoring and in some circumstances may prompt early delivery."
The study found that more than three-quarters of twins born naturally under the supervision of an obstetrician were successful and infant illness rates were no different to those who were delivered by a planned caesarean section.
Dr Breathnach said: "When it comes to how best to deliver twins, this is a contentious issue internationally. It is important to acknowledge that in more than half of twin pregnancies in this study, delivery was by caesarean section without any attempt at labour.
"Through this study we have demonstrated that under appropriate conditions and with careful patient selection, a high prospect of successful and safe vaginal delivery can be achieved with a trial of twin labour."
She pointed out that the study would enable obstetricians to take appropriate steps to minimise the risk during birth in order to provide the best outcome for mother and babies.