18 Nov 2010
Mums-to-be who undereat or overeat may predispose their offspring to a lifetime of obesity.
Pregnant women who overeat or undereat may be setting up their babies for a lifelong weight problem, as research is now showing that obesity has its roots in the womb.
This means that some people may be predisposed to a lifetime of obesity before they have even tasted a morsel of food.
Unfair? You bet. It makes the common wisdom to eat for two during pregnancy really bad advice.
Doctors say expectant mothers should focus on an optimal weight gain throughout the pregnancy through a sensible diet.
With Singapore’s obesity rate creeping up – from 6.9 per cent of the population in 2004 to 10.8 per cent in the National Health Survey conducted this year – the Health Promotion Board (HPB) will for the first time focus on prevention programmes for expectant mothers.
The Healthy Origins Programme (Hope) will cover pregnant women and parents of tots up to age two, while the Firm Foundations Programme will be for parents of kids up to six years of age.
Details of both programmes – to be rolled out next April – will be announced later this month.
Dr K. Vijaya, director of HPB’s youth health division, said the programmes “shift obesity prevention efforts further upstream” so healthy lifestyles are taught from an early age.
That is as early as before childbirth, as the foetal cellular environment can have long-term effects on health and diseases in later life.
Dr Tan Thiam Chye, consultant obstetrician and gynaecologist at KK Women’s and Children’s Hospital (KKH), said: “There is sufficient research that shows the foetal origins of metabolic diseases such as obesity, hypertension and diabetes.”
Malnourished mothers
Ironically, mothers who do not take in enough nutrients during pregnancy may risk their babies becoming obese as much as mothers who overindulge.
A foetus in the womb receives all his food and nutrients from his mother.
If he is not getting enough nutrients because his mother is not eating enough, his body will compensate and ensure a good chance of survival by becoming very efficient at storing fat, said Associate Professor Chong Yap Seng, senior consultant at the department of obstetrics and gynaecology at National University Hospital.
This is all right if the baby is born into a world where he will need his reserves because of a lack of food.
But if he is born into an environment that has ample food supplies, then the child will always accumulate more fat than he needs as he has been programmed to do so.
Prof Chong calls it a “mismatch”, which increases the baby’s risk of obesity in childhood and adulthood.
Studies have also shown that such babies may be at increased risk of developing heart disease and diabetes mellitus later in life.
During the Second World War when the Netherlands was under German occupation and food was scarce, pregnant Dutch women were malnourished and gave birth to small babies.
In the subsequent generations, it was observed that the mothers continued to have small babies despite improved post-war conditions. This showed how environmental factors can cause changes in gene expression – producing a generation of smaller than average babies – without altering the fundamental genetic code (DNA sequence), said Dr Tan.
These small babies were tracked into adulthood. Although not all of them became obese, there was a higher proportion of them who were overweight as compared to the population, added Prof Chong.
Overweight mothers
At the other extreme, women who are already overweight before pregnancy as well as those who put on excessive weight during pregnancy have offspring which may not fare well either.
Dr Chee Jing Jye, medical director of The Obstetrics and Gynaecology Centre, explained that if a pregnant woman overeats, it will expose her foetus to higher levels of blood glucose and free fatty acids.
Such exposure in the uterus may result in long-lasting changes in proportions of fat and lean body mass, which permanently affect the appetite control, metabolism rate and thus the offspring’s future risk of obesity, she added.
Dr Tan Eng Loy, associate consultant gynaecologist at the Singapore General Hospital, said that medical conditions – whether pre-existing or developed during pregnancy – such as diabetes may lead to increased birth weight of the baby, who may subsequently grow up to develop obesity.
Dr Christopher Ng, obstetrician and gynaecologist at GynaeMD Women’s and Rejuvenation Clinic, pointed to a study published in the American Journal Of Clinical Nutrition in 2008, which showed that the risk of being overweight at age seven was 48 per cent higher for children of women who gained more weight than recommended during their pregnancies.
Not eating for two
To avoid programming her child to a lifetime of obesity, Dr Tan of SGH advised women to start a healthy diet before they get pregnant and to maintain an optimal weight throughout their pregnancy.
He said: “If the claim that a pregnant woman is eating for two involves doubling the caloric intake, it is definitely not valid.”
A pregnant woman should take in only an extra 300 calories per day, said Dr Julinda Lee, obstetrician and gynaecologist at Pacific Healthcare Specialist Centre.
This translates to an extra snack or two in the day – and a healthy one, such as nuts, yogurt or a small sandwich, at that.
Dr Ng suggested increasing the intake of food high in fibre and low in fat, such as orange juice and leafy vegetables.
As obesity is a complex issue where multiple factors have to be considered – though no one can yet tell how big a role each factor plays – the ongoing debate about the effects of nature versus nurture continues, Dr Tan of SGH said.
He said that women should not be unduly worried about whether it is their fault that their children end up obese as a result of what they ate during pregnancy. What is more important is that they heed the advice of their doctors, eat right and in moderation before and during pregnancy, and teach their children healthy lifestyle habits.
The risk of being overweight at age seven is 48% higher for children of women who gain more weight than recommended when pregnant
Undereating will result in the foetus programming itself for a good chance of survival by being efficient in storing fat. When he is born into an environment that has ample food supplies, the child accumulates more fat than the body requires.
Overeating will expose the foetus to higher levels of blood glucose and free fatty acids. This may result in changes in proportions of fat and lean body mass and affect the child’s appetite control, metabolism rate and raise his future risk of obesity.
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Dept of O&G
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