Around one in four pregnant women seen by local hospitals were obese at the time of their first screening.

Health professionals have warned that women could be putting both their own and their baby's health at risk by not losing weight before getting pregnant.

Data from NHS Digital reveals that of 1,705 women weighed at their first antenatal booking appointments at Dorset County Hospital in the 12 months to April 2018, some 29 per cent were obese and a further 30 per cent were overweight.

When the number of underweight women is taken into account, the figures mean that less than 40 per cent of all expectant mothers seen by the trust were considered to be at a healthy weight at this stage of their pregnancy, which is typically between the ten and 12 week mark.

Tam Fry, a spokesman for the National Obesity Forum, described the numbers at Dorset County Hospital as "saddening".

He added: "Getting into shape before a conception and ensuring that you are eating healthily has been a long advocated message but too few heed it.

"A woman unhealthily overweight at booking in can not only be a health risk for her foetus but also for herself.

"The increasing number of babies being born already obese is also very concerning."

The figures are based on NHS body mass index (BMI) calculations.

According to both the NHS and the Royal College of Midwives (RCM), obese women are more at risk of a range of complications during pregnancy.

These include a higher chance of miscarriage, high birth weight, gestational diabetes, premature birth, thrombosis, pre-eclampsia and still births.

They may also suffer complications during childbirth, with the RCM warning that overweight and obese women are at a greater risk of having to have a caesarean section or experiencing haemorrhages or shoulder dystocia – where the baby gets stuck during delivery.

While the NHS advises overweight and obese women to lose weight prior to becoming pregnant, they do not recommend dieting once they have become pregnant.

Clare Livingstone, Professional Policy Advisor at the RCM, said: “While most overweight and obese women will have a straightforward pregnancy and birth, the risk of complication is increased to both mother and baby.

"For those presenting with a BMI of over 30, the National Institute for Health and Care Excellence (NICE) recommend dietary advice, moderate exercise and offer of referral to an appropriately trained professional, for example a dietician.

“Currently there is no consistent UK guidance on safe weight gain in pregnancy and the RCM, together with the Royal College of Obstetricians and Gynaecologists, is calling for evidence to develop guidelines for health professionals.”

Dorset County Hospital were not available for comment on the figures when approached by the Dorset Echo.