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A mother's milk provides the valuable nourishment a baby needs during its first months of life, but it seems women also provide a form of milk for their child while they are still in the womb.

Researchers have discovered that during the first months of pregnancy the mother's body secretes nutrients that have been dubbed 'womb milk' for the embryo.

This milk provide the embryo with the energy and biochemical building blocks it needs to grow during the first 11 weeks of pregnancy.

This computer reconstruction of an embryo developing in the womb shows the foetus at eight weeks. At this time it is still too small to receive nutrition from the mother's blood supply and instead absorbs 'womb milk'

During this time the embryo is too small and delicate for the umbilical cord to be attached and supply nutrients from the mother's blood supply.

Instead, researchers at the University of Manchester, have found that glands in the lining of the uterus produce a sugary substance known as glycogen and fragments of sugary protein.

These are absorbed into the placenta and then used by the embryo to grow.

Professor John Aplin, a specialist in reproductive medicine at Manchester University who led the research, said changes in a mother's diet or other factors such as smoking could also impact the build-up of these materials in the womb lining.

Speaking to New Scientist, he said: 'It could be that these trigger settings in the embryo that affect the risk of obesity or diabetes in life.'

Professor Aplin and his team, whose research is published in the journal Placenta, used womb, placenta and embryonic tissue donated by women who had undergone abortions.

The samples were stained using a dye to see where glycogen was present in the tissues from different stages of pregnancy.

They found the sugary molecule – which is used as a way of storing energy in the body – was present in high levels in the womb lining.

Here it is broken down into smaller molecules, like glucose, and is secreted out into a cavity between the lining of the uterus and the placenta – known as the intervillous space.

These cells also produce abundant levels of sugary protein fragments known as glycoproteins – some of which are known to play a role in protecting cells against infections.

The placenta absorbs these molecules and they are then used by the embryo to help it grow.

Breast milk provides valuable nutrients for young babies (like above) but it seems mothers provide another form of milk to the developing embryo while they are still in the womb by secreting sugary molecules 

Human embryos are able to receive nutrients from the mother's blood after around 11 weeks. Before then, the flow could dislodge it from uterus wall. The diagram above shows the development of the embryo in the womb

After about 11 weeks the levels of these secretions start to fade away – around the time that the embryo is big enough to accept nutrients via the umbilical cord.

Professor Alpin and his colleagues said: 'Our data are consistent with a model in which internalisation of glycoprotein is a major nutritional pathway in first trimester, continuing at a reduced rate into the second trimester as blood solute trafficking increases.'

The findings could also help scientists develop ways of improving fertility treatments like IVF by ensuing an embryo gets the nutrients it needs during the early weeks of development.

Professor Graham Burton, a reproductive physiologist at the University of Cambridge whose team first discovered that the uterus lining produced nourishment for the embryo in 2002, said: 'The first few weeks of pregnancy is a critical phase for embryonic development.

'Our understanding has been revolutionised over the past decade by the discovery that nutrients are supplied by these glands in the uterus lining during the first trimester – the so-called "uterine milk".'