Every week seems to bring another headline about Britain’s obesity epidemic. And with good reason. The number of obese 15 year olds has doubled over the past two decades. Children who are obese are more likely to be obese as adults, with all the risks to health this brings. Government concern about these statistics has led to a flurry of activity aimed at preventing obesity, such as including more sport on the curriculum and providing healthier school lunches.

Many have welcomed these measures as sound preventive policies. However, if we’re really going to tackle obesity we need to intervene earlier. Obesity among pre-school aged children has increased at an even greater rate than among school-aged children, trebling from 3 per cent 20 years ago to 9 per cent in 2004. It is becoming increasingly clear that nutrition and diet during the very earliest stage of a child’s life - pregnancy and the first year - is an important factor behind this problem.

We’ve known for some time now that low birth weight babies are more likely to die in their first year, have disabilities and hospitalisations as children, and suffer from illnesses as adults including heart disease and diabetes. Studies now show they are also more likely to become obese. It seems that babies deprived of adequate nutrition in the first two trimesters of pregnancy respond by enlarging their nutrient gate. This can translate to overly rapid weight gain after birth, and throughout life.

Breastfeeding decreases the incidence and severity of a range of childhood infections and allergies, and has also been linked to healthy brain development. Research has shown that babies breastfed for a year or longer are five times less likely to be obese by the time they start primary school than their bottle-fed peers. Low birth weight babies are at particular risk of obesity if they are bottle-fed. Bottles deliver more calories than breast milk and formula milk is less digestible, leading to weight gain that is too rapid.

Most practitioners and parents know that breast is best for babies. Far fewer understand the importance of effective weaning. Introducing high-carbohydrate, sugary foods like cereal and juice too early may lead to a process called "metabolic programming" - where the metabolism slows down so that it takes longer to burn calories, thereby increasing the chances of weight gain. Nearly half of mothers introduce solids before their baby is four months old, when the recommended minimum age is six months. Keeping a baby on a diet of mainly formula milk for too long can also lead to excessive weight gain. Formula milk supplies too high a level of calories after a baby’s first birthday, and is also lacking in several key nutrients, like iron.

Poverty is a key factor underlying all these issues. Babies born to mothers in social class V are 60 per cent more likely to be low birth weight than babies born in social class I. Nine out of 10 mothers in social class I initiate breastfeeding compared with just over half in social class V. Weaning is also affected by poverty. Families living on a low income may find it cheaper to continue bottle feeding their babies than to start weaning them onto solid food. A study in the most deprived wards in Peterborough found that half of children had a primarily milk-based diet at the age of 21 months.

A lack of practical information and advice about good nutrition during pregnancy and the first year of a child’s life is another important issue. For example, the high-sugar, high-salt diets that many adults eat are completely unsuitable for babies, but so too are the high-fibre, low-fat diets that are usually recommended for adults. A healthy weaning diet for babies should be rich in fruit and vegetables, as well as protein and unsaturated fats.

So what should be done to tackle these problems? Firstly, financial support for low income families should be increased during pregnancy. This could be done by providing a pregnancy premium for families on income support or by introducing a pregnancy tax credit so that women can start claiming child tax credit when they are pregnant. Another option would be to increase financial support in kind. Healthy Start (which is set to replace the Welfare Food Scheme) will provide low-income pregnant women and new mothers with vouchers to buy fruit and vegetables as well as milk and infant formula. However, women will only receive vouchers worth £2.80 a week. This is far too little when a modest but adequate diet during pregnancy costs around £20 a week.

Secondly, pregnant women and new parents need better information about healthy nutrition during pregnancy and their children’s early years, including breastfeeding. This isn’t simply a matter of providing women with leaflets or telling them what to do - it means providing practical help and advice. Sure Start and children’s centres provide an excellent model for delivering this support, with midwives and health visitors working alongside other professionals and voluntary groups in a community setting.

Pregnancy and the first year must be taken seriously in the fight against child obesity, or yet more babies will grow into unhealthy, unhappy children.

Jenny North is policy officer at the Maternity Alliance.

Tips for practitioners

• Midwives and Sure Start workers should target pregnant women who are likely to have a poor pregnancy diet with advice and support about their food choices.
• Provide support for particular client groups on cooking and eating healthily.
• Advise disadvantaged pregnant women and new mothers about how to claim benefits they are entitled to, including through the Welfare Food Scheme (which will become Healthy Start).
• Midwives and health visitors to set up peer support groups, where women who have breastfed or weaned successfully can provide help and advice to other new mothers.
• Ensure through training and information that GPs, midwives, health visitors and Sure Start workers routinely advise and support new parents on effective weaning, taking into account cultural issues, lack of income, and lack of knowledge about food preparation and nutrition.