The UK has the highest teenage pregnancy rate in Western Europe. In Scotland, one in ten babies are born to a teenage mother.
Teenage pregnancies are associated with increased risks of poor pregnancy outcome for both the mother and her newborn. Scientists in Aberdeen have been studying the problems of these teenage pregnancies using adolescent sheep as a model. They have shown that if adolescent sheep become pregnant while they are still growing, the nutrient supply from the mother to the fetus is reduced. This means that the lamb may not develop normally and will be very small at birth. These studies have implications for managing the pregnancies of the high numbers of teenagers worldwide who are becoming pregnant before they have stopped growing.
Dr Jacqueline Wallace at Aberdeen’s Rowett Research Institute 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,” said Dr Wallace.
Dr Wallace originally showed that overfeeding adolescent ewes during pregnancy to mimic rapid maternal growth in humans promoted the growth of the mother at the expense of the fetus. The reduction in fetal size occurred because the growth of the placenta was impaired and resulted in premature delivery of low birth weight lambs. Recent studies have focused on limiting the food intake of adolescent ewes during pregnancy to prevent maternal growth. This also reduced the nutrient supply to the fetus and slowed its growth. They also found that a change in the development of the blood vessels which supply nutrients to the womb and to the placenta may be a possible cause of the restricted growth of the fetus of these underfed adolescent sheep.