The ageing process begins in the womb but can be slowed if pregnant women take antioxidants, scientists said today.

A Cambridge university-led international study found the offspring of mothers with lower levels of oxygen in the womb aged more quickly in adulthood.

Lower oxygen levels can be a consequence of smoking during pregnancy, pre-eclampsia or living at high altitude. The British Heart Foundation, which funded the research, said it showed the importance of mothers-to-be maintaining a healthy lifestyle.

Researchers measured the length of the end section of chromosomes, or telomeres, in the blood vessels of rats. Telomeres are the equivalent of the plastic wrapping on the end of shoelaces and prevent chromosomes from fraying. As we age, telomeres become shorter, and their length can be used as a proxy to measure ageing.

Adult rats born from mothers that had been placed in a room with seven per cent less oxgyen had shorter telomeres than rats born from uncomplicated pregnancies, and experienced problems with the inner lining of their blood vessels.

Rats born to mothers receiving antioxidants and normal levels of oxygen during pregnancy had longer telomeres.

Professor Dino Giussani, the study’s senior author, said: “Our study in rats suggests that the ageing clock begins ticking even before we are born and enter this world, which may surprise many people.

“We already know that our genes interact with environmental risk factors, such as smoking, obesity and lack of exercise to increase our risk of heart disease, but here we’ve shown that the environment we’re exposed to in the womb may be just as, if not more, important in programming a risk of adult-onset cardiovascular disease.”

Dr Beth Allison said: “Antioxidants are known to reduce ageing, but here, we show for the first time that giving them to pregnant mothers can slow down the ageing clock of their offspring. Although this discovery was found using rats, it suggests a way that we may treat similar problems in humans.”

Professor Jeremy Pearson, Associate Medical Director at the BHF, said: “Although conducted in rats, this research emphasises the need for pregnant mothers to maintain a healthy lifestyle for the sake of their baby’s future heart health.”