Blood flow in the fetal liver linked to mother's slimness and diet

Researchers have discovered a link between the amount of blood flowing through the liver of the unborn baby in late pregnancy and the diet of expectant mums. In slim mothers and those who eat an unbalanced diet the amount of blood flowing to the liver is increased. While this 'liver-sparing' pattern of blood flow is thought to protect the foetus from a nutrient deficit, the researchers believe it may also affect liver function in later life, increasing the risk of adult heart disease and diabetes in the offspring.

To determine how a mother's diet and slimness might have long-term effects on the health of her baby, researchers from the Universities of Southampton, Bergen and Oslo used ultrasound to measure blood flow to the liver of the developing baby late in pregnancy. The researchers studied a group of 381 healthy babies whose mothers are part of a large project studying nutrition before and during pregnancy.

Their findings, published this month in the American journal Circulation Research, suggest that the babies of slimmer mothers with lower body fat stores and those eating an unbalanced diet have greater liver blood flow and divert less blood away from the liver in late pregnancy. This change in blood flow may cause subtle changes in the development of the liver and alter the baby's ability to cope with a high-fat "Western" diet in later life, thereby predisposing to adult heart disease and diabetes. The research suggests that improving a mother's nutrition before she conceives could have lifelong benefits for the health of her baby.

The mothers in the research study are part of the Southampton Women's Survey, a unique study of nutrition before and during pregnancy. By measuring the growth and development of the babies during the pre-school years the researchers hope to identify whether or not the liver blood flow adaptations in the womb have long-term implications.

Dr Keith Godfrey, a scientist in the Medical Research Council (MRC) Epidemiology Resource Centre at the University of Southampton's School of Medicine, who led the study, commented: "During pregnancy, the developing baby is wholly dependent upon the mother for an adequate and appropriate supply of nutrients. This research is the first work to recognise that a mother's slimness and diet alter the circulation of blood in her developing baby in the womb. As a mother's slimness and unbalanced diet during pregnancy have been linked with susceptibility to heart disease and diabetes in the offspring in later life, the findings may have important implications.

"The observations suggest that before birth many normal babies adapt to the supply of nutrients from the mother and alter the amount of blood flowing to the liver. We believe that this 'liver-sparing' adaptation could help the baby to continue growing in the womb, even if the mother's body is not able to supply the nutrients needed by the baby. However, the adaptations could have long-term consequences for how the liver deals with fat and other nutrients after birth."

Dr Guttorm Haugen, of the Department of Obstetrics and Gynaecology at the University of Oslo and a member of the research team, commented: "Further research is required to confirm our findings and to define if the changes in a baby's blood circulation before birth have any long-term consequences. Our observations offer insights into the circulatory tuning of the fetal liver in relation to a mother's slimness and diet. The concept of 'liver-sparing' could lead to new diagnostic measures to investigate how maternal slimness and unbalanced diet increase the risk of adult heart disease and diabetes in the offspring."

The study was made possible by using data from the Southampton Women's Survey, which started in 1998. Since then, researchers from the MRC and the University of Southampton have interviewed 12,500 women in their homes, and followed over 2,000 women through pregnancy.

The Southampton Women's Survey builds on work conducted by the MRC at the University, which has shown that growth from the very earliest days in the womb affects health in adulthood, particularly the risks of heart disease, diabetes and osteoporosis.

The research reported this month uses ultrasound measurements of the baby's circulation. The technique was developed in Norway, mainly at Haukeland University Hospital in Bergen, one of the leading centres for Doppler ultrasound in obstetrics in the world. The collaboration included Dr. Guttorm Haugen from the University of Oslo, the leading university of Norway, where nutrition is one of the main research fields, and where perinatal nutrition was recently pronounced a particular focus. Dr Haugen has developed the techniques to a new level and provided very useful research tools for further studies of fetal development.

This work is supported by the charities The British Heart Foundation and Hope, by the University of Southampton and by the Medical Research Councils in the UK and Norway.