INDEPENDENT NEWS

Where did all those multiples come from?

Published: Tue 6 Sep 2011 03:30 PM
Where did all those multiples come from?
At the New Zealand Multiple Birth Association we often get asked, “Why are there so many twins and triplets around these days?”. The answer is that the numbers of multiples has increased, but only at the same rate as the general population. The number of multiples born in New Zealand has remained steady over the last 10 years at between 1.5-2% of all births. Of course with the New Zealand ‘baby boom’ over the last five years more multiples have been born.
The other factors that contribute to the number of multiples in the population include increasing maternal age, advances in medical techniques and technology and, to a lesser extent, assisted reproductive technologies.
As most people are aware the maternal age of first time mothers has been increasing over the last decade. In 2010 Statistics NZ published an article that showed mothers of multiples tend to be older still. We know that as women age, the chances of them having a multiple birth increase. In 2009, 58 percent of mothers of multiples were over 30 compared with 49 percent of mothers having single babies (or singletons as we call them). The median age of all mothers giving birth in 2009 was 30 years whilst the average age of mothers having twins was 34 years old.
Medical technology has improved significantly, resulting in increased survival rates for multiple birth babies. Antenatal monitoring (during pregnancy) and care after birth for premature infants has enabled babies born at earlier gestations to survive. Scanning technology has assisted in diagnosing multiples as soon as they are suspected, and the pregnancy can be more closely monitored. Lead Maternity Carers are then able to recommend a course of care that improves the chance of multiples being born safely.
Babies from multiple pregnancies have an increased risk of being preterm. The 2006 Australia New Zealand Neonatal Network (ANZNN) perinatal report shows that over 20% of the total number of babies admitted to neo-natal intensive care units in New Zealand were from multiple births. In 2006 20% of all multiples born that year were admitted to NICU. This is compared to 2.7% in the total population.
The improved technology and knowledge within the neo-natal area has meant that smaller and earlier babies are surviving. Of the ANZNN registrants from multiple births 1,051 (59.6%) were born before 32 weeks gestation and 1,730 (98.2%) were born before 37 weeks gestation and half the babies from a multiple birth, 1,050 (59.6%) weighed less than 1,500 grams.
The other area, often over represented by the general public as the ‘cause’ of twins and triplets, is assisted reproduction technologies, including IVF. The most important recent trend in Australasia is the reduction in the number of twins being conceived through Artifical Reproduction Technology (ART). The reduction in the rate of ART twins and triplets birth is due to more people taking up Single Embryo Transfer (SET). This increased from 40.5% in 2004 to 67.8% in 2008. In 2010 approximately 8% of all IVF babies were multiples, which in actual numbers is 46 sets of twins (and 2 sets of triplets) out of 887 sets born that year. This equates to only 5% of multiple births in New Zealand, being due to IVF.
Every year in the first week of October the New Zealand Multiple Birth Association celebrates Multiple Birth Awareness Week. Look out for your local club in your community and help them celebrate the special group of children that are multiples!
ENDS

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