Exercise can help pregnant women give up smoking, two new studies show.

Researchers found a quarter of mums-to-be who exercised regularly were able to kick the habit before giving birth.

Dr Michael Ussher who led the team from St George's University of London, said: "These results are very encouraging.

"Regular exercise is ideal for any pregnant women who smoke as it's obviously safe and the benefits are enormous."

Despite the warnings, around 17 per cent of women in the UK admit to smoking throughout pregnancy, often in secret because they fear disapproval.

This can lead to miscarriage, lower birth weight and is linked to learning difficulties, problem behaviour and asthma in childhood.

Nicotine patches are one way to help smokers give up, but there are worries they may harm the foetus.

Experts say exercise is a healthy alternative that can reduce cravings experienced by smokers.

The two pilot studies included women over 18 who smoked at least one cigarette a day and were 12 to 20 weeks into their pregnancy.

In one trial, women exercised under supervision once a week for six weeks while in the other they worked out twice a week for the same length of time and then once weekly for three weeks.

The exercise including walking, using a treadmill or exercise bike.

In addition, all the women received counselling and help to stop smoking.

The studies found a quarter of the 32 women gave up smoking before giving birth.

The researchers are now conducting a larger trial of more than 850 women.

两项最新的研究表明：锻炼可以帮助怀孕的女性戒烟。

研究人员发现，有四分之一的准妈妈在生育之前通过规律性的锻炼可以戒掉吸烟的毛病。

迈克尔乌雪医生带领着来自伦敦圣乔志医院的研究小组，他说：“这些结果很令人鼓舞。”

“规律性的锻炼对于任何吸烟的怀孕女性来说都是理想的，应为它明显安全而且益处很大。”

尽管收到警告，在英国还是有17%的女性承认在怀孕期间吸烟，大多数时候都是私下进行的，因为她们怕遭到反对。

这会导致流产，低出生体重，并会导致孩子在幼年时的学习困难，问题行为和哮喘。

尼古丁贴剂是帮助吸烟者戒烟的一种方法，但有人担心它们会对胎儿有害。

专家指出，锻炼是一种很健康的替代方法，它能减少吸烟者对烟的渴望。

这两项初步研究调查了十八岁以上的女性，她们每天至少吸一根烟并已怀孕12到20周。

在一个试验中，一部分女性被监督每星期锻炼一次，共锻炼六个星期；其他人则每星期锻炼两次，坚持相同的时间然后改为每星期锻炼一次，锻炼三个星期。

所进行的锻炼包括步行，使用跑步机或健身车。

另外，所有的女性都得到顾问和帮助，以使其停止吸烟。

研究发现32名女性中有四分之一的人在生育之前戒烟了。

研究人员目前正在进行一项更大的、超过850名女性参加的试验。