If you think downward dog is difficult now, imagine doing it six months pregnant.
A mother's stress during pregnancy is recognised as being bad for the baby, and has been linked with premature birth, low birth weight and developmental problems in young children and even teenagers. Anxiety has also been linked with post-natal depression.
The results of new research led one expert to suggest yoga should be provided on the NHS for mums-to-be as a cheap way of preventing serious complications later.
Yoga has been espoused by experts and celebrities as a way of de-stressing, and actresses such as Gwyneth Paltrow, Drew Barrymore, Jessica Alba and Sienna Miller are all said to have used the ancient techniques while pregnant.
And while medical professionals have long recommended yoga as a way of tackling stress, scientists have now tested the theory in a research setting.
In a paper published today in the journal Depression and Anxiety, academics from Newcastle and Manchester Universities show that women who attended a yoga class every week for eight weeks experienced less anxiety compared to those who received normal antenatal treatment.
Dr James Newham, a research associate at Newcastle University's Institute of Health and Society, but who carried out the work while at Manchester, said: "It is surprising this has never been looked at before, we have long believed that it works but no research had been done to back up the theory.
"We have now gone some way to prove that it can help.
"It was not a small effect either. This has the potential to really help mothers who are feeling anxious about their pregnancy."
Professor John Aplin, one of the senior investigators in Manchester, and himself a yoga teacher of long standing, said: "Yoga incorporates relaxation and breathing techniques with postures that can be adapted for pregnant women.
"Many women opt to practise yoga during their pregnancy but this is the first worldwide report on the effects of both single and multiple sessions of antenatal yoga on mood."
The study, funded by baby charity Tommy's, was carried out in Greater Manchester and looked at 59 women who were pregnant for the first time and asked them to self-report their emotional state.
They were split into several groups, some of which took part in a yoga session a week for eight weeks, while the others just had normal pre-natal treatment.
A single session of yoga was found to reduce self-reported anxiety by one third and stress hormone levels by 14%.
Similar findings were made at both the first and final session of the eight-week intervention.
Professor Aplin said: "The results confirm what many who take part in yoga have suspected for a long time.
"There is also evidence yoga can reduce the need for pain relief during birth and the likelihood for delivery by emergency caesarean section.
"Perhaps we should be looking at providing yoga classes on the NHS.
"It would be relatively cheap to implement, could help mothers and their children be healthier, as well as reducing the costs of longer-term health care."
Jacqui Clinton, health campaigns director at Tommy's, said: "We already know that pregnancy yoga can help improve physical health and strength on the run up to having a baby, and this new evidence shows that it may have important benefits for women's emotional health too."
Cheryl MacDonald, founder of YogaBellies which specialises in perinatal yoga and natural birth preparation, says: “This research highlights the key benefits that yoga can have on women who are expecting. Yoga is so much more than just a fitness class; it focuses on the mind, body and soul. When a woman is pregnant, her body undergoes huge changes that are emotionally and physically draining. Perinatal yoga is not only about building strength and stamina for birth or learning effective breathing techniques, but also about bonding with your baby, even in utero, and learning to accept your role as a mother.
“These results are academic proof of what we have believed for a long time – that you can’t under-estimate the thorough benefits of yoga, particularly for pregnant women. It helps to reduce antenatal depression and keep women fit and healthy – physically and emotionally, and encourages them to look forward to meeting their baby and not feel so petrified of the birth process.”