Small babies 'explained by sheep'

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Pregnant adolescent sheep having small lambs may explain why teenage mothers have underweight babies, according to researchers.

Younger sheep becoming pregnant while still growing means the nutrient supply from the mother to the foetus can be reduced - leading to small lambs.

Scientists at Aberdeen's Rowett Research Institute say this has diet implications for teenage mothers.

The UK has the highest teenage pregnancy rate in Western Europe.

The researchers studying teenage pregnancy used adolescent sheep as a model.

We believe that our research highlights the importance of ensuring that pregnant teenage girls gain adequate, but not excessive amounts of weight Dr Jacqueline WallaceRowett Research Institute

They said the study has implications for managing the pregnancies of the high numbers of teenagers worldwide who are becoming pregnant before they have stopped growing.

Dr Jacqueline Wallace, who led the research, said: "Our studies show that there is competition for nutrients between a mother and her developing offspring when the mother herself is still growing, and that it is the newborn who comes off worse in this situation.

"It follows that formulating correct dietary advice for teenage girls is likely to be complex, particularly if the mother is still growing.

"We suggest that assessments of growth and nutritional status at the time of conception and at mid-pregnancy, and the use of ultrasound to detect whether placental growth and function has been affected, may prove beneficial in the optimal management of teenage pregnancies."

Premature delivery

Dr Wallace said that overfeeding adolescent ewes during pregnancy to mimic rapid maternal growth in humans promoted the growth of the mother at the expense of the foetus.

The reduction in foetal size was said to have occurred because the growth of the placenta was impaired and resulted in premature delivery of low birth weight lambs.

The UK has the highest teenage pregnancy rate in Western Europe

Dr Wallace said: "We believe that our research highlights the importance of ensuring that pregnant teenage girls gain adequate, but not excessive amounts of weight, especially during the early stages of their pregnancy when the placenta is formed.

"The problems associated with being an adolescent or teenage mother are particularly serious when mothers are under 16 years of age and hence still potentially growing.

"For these very young mothers, the risk of having a low birth weight baby is doubled. There is also an increased risk of a premature birth, infant mortality and maternal death due to obstetrical complications."

Prof Peter Morgan, director of the Rowett Research Institute, said: ''The implications of this research are particularly relevant in the light of the current interest and priority given to health inequalities in the UK."

The research was conducted in collaboration with colleagues at North Dakota State University and was funded by the National Institutes of Health, USA and the Scottish Government.

The research has been published in Biology of Reproduction.