Redland Bay resident Carole Adams thinks “there might be something in the water” at her workplace.

At Bayside Park Early Education Centre there are currently eight sets of twins – down from 10 sets at the end of last year – out of 58 enrolments. Adams is herself a mother of grown-up twins and two fellow staff members have twins as well.

All but one set of those twins are not identical but fraternal twins, and the centre on Brisbane’s bayside could well be a microcosm of what has become a national trend which has seen a dramatic increase in the rate of fraternal twins (created when two eggs are fertilised separately) over the past two decades, rising from about one in 90 births to one in 70.

The main reason for the change, according to Professor Nick Martin, director of the Queensland Twin Register at the Queensland Institute of Medical Research, is that more mothers are delaying childbirth.

By age 37 the frequency of having fraternal twins is four times higher than for women at age 18. Another reason for the increase is that more mothers are using reproductive technology such as IVF, where more than one fertilised egg may be implanted at a time.

The increase in the twin rate means more parents today are facing the challenge of raising twins than ever before. Multiple birth babies face more immediate health challenges than single babies. For example, pre-term births occur in more than 56 per cent of all twins and in all high order multiple births, compared to only 6.6 per cent for singleton babies. But such challenges are just the beginning with twins facing comparisons and rivalry throughout life, and parents struggling with the escalating costs of raising them.

This is why the Australian Multiple Birth Association (AMBA) is lobbying the government for financial assistance for parents of twins.

According to AMBA’s Bree Mort, twins have a significant impact on a family’s budget. While the Federal Government has estimated the cost of raising a single child to the age of 18 is close to $400,000, one social researcher puts the cost at closer to $1million as children stay at home longer and parents have to foot the bills for costly technology, private tutoring and activities. Following a study into the cost of raising a child to age 21 in the UK, it was estimated that the average cost of raising twins is at least 50 per cent higher.

Government assistance is currently available to families with triplets or more multiples – but not twins – and the AMBA wants the wording for “higher multiple allowance” to be changed to take in all multiple birth children, including twins.

The change would certainly benefit Ormiston mother Samantha Hilton, who has not one, but two sets of fraternal twins – Dashiell and Riley, aged 5, and River and Zoe, 2 – yet cannot access the multiple birth allowance under the current arrangements.

However, some things about raising twins already have changed. For example, 20 years ago many schools forced twins to separate into different classes but these days, according to twins researcher and retired psychology professor David Hay, there are no fixed rules and some children cope better on their own than others.

Samantha Hilton’s youngest twins go to the Bayside Park Early Education Centre where Carole Adams is director. Adams says it’s important that each child is looked at as an individual and Hilton couldn’t agree more, having two sets of twins who are all very different in personality. “Don’t expect that because one child likes to do a certain activity that the other twin is going to want to do exactly the same,” Adams says.

But do twins have psychic powers – can one read the other’s mind, or know if their twin is in pain? Professor Nick Martin is sceptical. He interacts with twins every day at the Queensland Twin Register, where identical twins and non-identical twins are used to study melanoma risk factors and susceptibility to other diseases. “When you consider identical twins are two individuals who have exactly the same genetic makeup, their brains are very similar, all their experiences are very similar, their environment is very similar, the fact they sometimes think the same thing at the same time or that they are able to anticipate things happening to the other twin to me is not particularly remarkable,” he says.

For information about support call the Australian Multiple Birth Association on 1300 886 499.