August 13, 2013

expert reaction to obesity in mothers and heart health in their adult offspring

A study published in the BMJ found children of obese and overweight women had a higher risk of early cardiovascular death as adults.

Dr Susan Ozanne, Reader in Developmental Endocrinology, University of Cambridge, and British Heart Foundation Senior Fellow, said:

“Although these findings are interesting and important, until the confounding effects of other factors such as obesity in the offspring themselves can be accounted for, we cannot assume a causal relationship between obesity in pregnancy and heart problems in adult children of these women – more research is needed to establish this. Obesity runs in families (for a number of reasons) and obese people are more likely to develop heart disease. At this stage based on these findings we don’t know if it is the maternal obesity during pregnancy that is having a direct effect on the offspring’s heart. It is possible that the association results because the offspring of the obese mother is more likely to be obese themselves and therefore at increased risk of heart disease. Furthermore, the fact that an obese mother is more likely to have an obese child could be related to the child being exposed to an obesogenic environment in the womb, but there are other contributing factors too (such as mother and offspring having a shared environment after the child is born, and also genetics).

“It is a complex issue which definitely needs more research. Until we have the results of further research, it would be unwise for any pregnant woman to drastically change their diet as this may be harmful in both the short and long term to both mother and child.”

Dr Tim Chico, Senior Clinical Lecturer and honorary Consultant Cardiologist, University of Sheffield/Sheffield Teaching Hospitals, said:

“This is a worrying finding. It suggests the current obesity epidemic will lead to an increased risk of heart disease even in babies born in the future. The reason why children of overweight and obese mothers suffer an increased risk of heart disease is unclear, and from this study we cannot be sure whether it is because the children are more obese themselves due to genetic and/or environmental reasons, or whether there is some direct effect of maternal obesity during pregnancy on the offspring’s heart itself.  Either way, the study emphasises the importance of trying to maintain a healthy weight. No parent wants to think that their actions might affect the health of their children, and this is often a powerful motivation to change our behaviour. The message of this study is clear; if a mother is overweight, it may be her children that pay the price. The causes of obesity are complex, and it is not just the fault of the person who is overweight. We have made ourselves a society where it is difficult to take exercise, due to pressure of time and lack of opportunity, but very easy to find cheap, high calorie food. I’ve seen heart disease decline over my career, but it is quite possible this will reverse as we begin to see the consequences of an environment that makes it very difficult to stay thin.”

Professor Sir Stephen O’Rahilly, Professor of Clinical Biochemistry and Medicine, University of Cambridge, said:

“As the authors themselves acknowledge, obesity runs in families.  We have known for decades that your chances of being obese are increased if one of your parents is obese and markedly increased if both parents are.  We know from studies of identical versus non-identical twins that a large part of this familial tendency is down to the genes we inherit from our parents.  Obese people are at higher risk of heart disease, so it is very likely that the people in this study whose mothers were obese were fatter than those whose mothers were lean.  We don’t have that information in the case of this study, because standard death certificates do not contain information on the deceased person’s height or weight.  Although there are compelling reasons to try to avoid severe obesity in pregnancy – several relating to difficulties obese women can have at the time of delivery – this study does not provide any information regarding the risks or benefits to the adult offspring of a mother who actively alters her diet in pregnancy to avoid or reverse obesity.  It is conceivable that drastic dieting undertaken during pregnancy could be actively harmful rather than beneficial to the offspring.”

Dr Gail Rees, Lecturer in Nutrition, Plymouth University, said:

“This study adds to current evidence that shows being overweight or obese during pregnancy can have long lasting detrimental effects on the health of the offspring. The study examined hospital records of over 37 thousand individuals (now aged 34 -61 years) and their mothers, from 1950 to present day.

“These results demonstrate an association between obesity during pregnancy and the risk of premature death and hospital admissions due to heart disease in adult offspring. However the study doesn’t show how obesity in the mother causes the increased risk of disease. It is not possible to separate the contributions from genetics, uterine environment or later lifestyle to the premature death.

“However from other studies we know that obesity during pregnancy is associated with changes in the mother’s metabolism which alters the environment for the developing fetus. For example obesity causes higher than normal blood sugar levels in the mother which increases the energy supply to the fetus. Consequently the fetus stores this extra energy as body fat. Also there are changes in the fetal metabolism which alter hormone levels and structure of the developing organs. This may contribute to changes in the regulation of appetite, metabolism and organ function in later life.

“If women are overweight during their pregnancy, it is important not to try and lose weight but to eat a healthy varied diet, remain active and discuss appropriate weight gain with their midwife.”

Dr Daghni Rajasingam, Royal College of Obstetricians and Gynaecologists spokesperson, said:

“This is a large scale study and highlights the potential risk factors associated with obesity.

“We know that obesity has a major impact on women’s health and this paper highlights the need to prevent obesity in women of childbearing age and encourage them to adopt healthy lifestyles through regular moderate physical activity and eating well. This approach should be adopted throughout a woman’s life. This life-course approach should also be applied to offspring as this study illustrates.

“If pregnant women are worried about their weight in pregnancy they should talk to their doctor or midwife to discuss their concerns.”

Doireann Maddock, Senior Cardiac Nurse, British Heart Foundation (BHF), which part-funded the study, said:

“We know that a mother’s health in pregnancy can affect the health of their unborn baby. But this study suggests an association between a mother’s weight in pregnancy and her child’s risk of dying prematurely in adulthood.

“Further research is needed to understand this association but this study emphasises the need for everyone, but in particular pregnant women, to try to eat healthily and be active.”

‘Maternal obesity during pregnancy and premature mortality from cardiovascular event in adult offspring: follow-up of 1,323,275 person years’ by Rebecca M Reynolds et al. published in the BMJ on Tuesday 13 August 2013.