The odds of conceiving identical triplets are often wildly exaggerated and could be contributing to feelings of isolation in women already dealing with these high-risk pregnancies, according to the Australian Multiple Birth Association (AMBA).
Reports quote widely varying statistics for identical (monozygotic) triplets, ranging from 1 in 60,000 to 1 in 200 million. Identical triplets are conceived when one fertilised egg splits into two and then one of those two splits again.
Triplet mum and AMBA Communications Director Ali Mountifield says, “We can’t see any data supporting the 1 in 200 million figure – if that was right, there’d only be 35 sets of identical triplets in the world. There’s easily that many in Australia.”
“The best statistics I’ve found that seem to correlate with the data we’re seeing in Australia is from Mothers of Supertwins (MOST) in the US. Their data shows that the chance of having identical triplets is 1 in 62,500 pregnancies.”
AMBA provides the following Australian figures for context:
- Australian Bureau of Statistics data shows that of the 305,079 births in 2012, 4,480 of these – 1.5% – were sets of multiples, ie when one pregnancy results in two or more babies.
- 59 of the 4,480 multiple births – 1.3% – were sets of Higher Order Multiples (HOMs), ie when the pregnancy results in three or more babies.
- According to information supplied to AMBA by 34 families of HOMs born in 2012, at least 34 of the 59 were sets of triplets (no quadruplets or more were reported).
- Five of these sets – 14.7% – were identical triplets.
- Four sets – 80.0% – were conceived ‘naturally’, ie without assisted reproductive technology.
Ms Mountifield says, “When we look at the data available, we estimate the probability of an Australian couple naturally conceiving identical triplets is around 1 in 76,269 births. However, this is probably slightly lower considering 25 families of the 2012 HOM births didn’t connect with AMBA for support and provide information on their newborns.”
Mum to two-year-old identical triplet boys Karen Guthrie says, “The Australian HOM community is interested in getting some integrity in the numbers available to help expectant families know that they are not alone and to ‘normalise’ their extraordinary pregnancy a little. We also feel that a clarification of the numbers will help the medical community manage identical triplet pregnancies and the associated risks. Only a few days ago one woman said her doctors originally assumed her triplets couldn’t be identical because that would have ‘been unheard of’.”
According to MOST, the overall chance of conceiving triplets of any zygosity (fraternal or identical) is 1 in 6,889 pregnancies.
For local case studies or further comment/information from AMBA please contact:
Ali Mountifield, AMBA Communications Director
Email: communications@amba.org.au
Mobile: 0411 250 758
www.amba.org.au
