Vic: Twins may hold key to baby growth deficiency

AAP General News (Australia)
04-29-2007
Vic: Twins may hold key to baby growth deficiency

MELBOURNE, April 29 AAP - They're becoming commonplace in the classrooms, now twins
may provide the answer to a mystery that their singleton siblings could not.

A Melbourne obstetrician is studying placentas from twin pregnancies in a bid to understand
- and ultimately reduce - in utero growth problems.

Nicola Bryan will test placentas from 30 sets of twins over two years to identify what
causes discordant growth in non-identical twins.

Results may ultimately help reduce in utero growth deficiency, which can lead to an
increased long-term risk of cardiovascular disease, hypertension, hardening of the arteries
and diabetes.

A pilot study in singleton, or one-child, pregnancies identified a decreased expression
of the HLX (or homeobox) genes, which controls growth.

But studying twin pregnancies allows Dr Bryan to compare growth-deficient and normal
placentas from the same maternal environment.

"The singleton study doesn't allow for maternal variation," Dr Bryan said today.

"The twins study allows for controls (on influencing factors such as blood pressure
and diet) in mothers."

The numbers of twins are rising in Australia, due largely to an increase in the number
of older mothers - who are more likely to have a multiple birth - and the growing acceptance
of fertility programs.

Dr Bryan said while multiple pregnancy growth rates were more difficult to monitor,
information gained from the births was valuable.

Early results seemed to confirm the HLX theory, but there were still more genes to
test, she said.

Dr Bryan, a consultant obstetrician and research fellow at Melbourne's Royal Women's
Hospital, said poor growth in the womb had lifelong implications.

"We've always attributed poor growth to a placental cause but we need to identify the
placental cause to address it," she said.

"If (the problem is) picked up and addressed and the baby's delivered in good condition,
we're minimising the long-term problems."

Growth-restricted babies are smaller than 97 per cent of other babies at the time the
condition is discovered, which normally occurs during the later stages of gestation.

Doctors currently rely on scans to monitor a baby's growth rate throughout the remainder
of the pregnancy but identifying the cause of growth deficiency may lead to a breakthrough
treatment.

"We don't know what the strategy is yet, we don't know what the significance is of
the (HLX gene) discovery," Dr Bryan said.

"We hope to reduce the incidence of growth restriction and improve the outlook of babies
born small for gestation."

AAP rgr/cjh/mn

KEYWORD: BABIES

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