Sammy Warnes, 30, claims she spends around £10 on marijuana every three weeks after hearing that it could ease the symptoms of hyperemesis gravidarum.

However consultant gynaecologist Dr Shree Datta has now warned that cannabis can increase the risk of pregnancy complications, such as stillbirth, premature birth and low birth weight.

She told Metro.co.uk: ‘Cannabis has been linked to a higher risk of complications during pregnancy.

‘Whilst babies do not normally experience any serious signs of withdrawal there has been some research to indicate a risk of developmental issues.

‘It can also be difficult to know if any other chemicals have been added to the cannabis you are consuming and there is an unknown risk as to how that may impact your pregnancy.

‘In general, I would advise against smoking cannabis or other substances during pregnancy until there is more research done on this. I would also advise against smoking cannabis in conjunction with other substance.’

Dr Datta, who works for MyHealthcare Clinic, added that the science around smoking cannabis during pregnancy ‘is thin’, meaning there is not currently enough research ‘to give a clear idea of all of the risks’.

She also warned that smoking the Class B drug after giving birth could still affect a baby’s early development.

Dr Datta continued: ‘The active ingredient in cannabis, delta-9-tetrahydrocannabinol (THC), can also be passed to the baby via breast milk – again there does need to be more research done.

‘But there is some evidence to suggest it may slow weight gain, make your baby sleepy and may mean they do not feed as well as they should, in addition to potentially affecting their development.’

She added that cannabis could also ‘increase the risk of schizophrenia or psychosis’, which could put new mums in higher danger of postpartum depression.

Ms Warnes said she first tried cannabis to relieve her severe morning sickness when pregnant with her daughter Arabella, who is now ‘fit and healthy’ and ‘doing fine at nursery’.

Her severe sickness had almost caused her to have an abortion, but she claims her symptoms disappeared at 25 weeks after inhaling ‘one or two puffs’ of a joint.

Now pregnant again, she says she only smokes ‘a few times a week’ after she was forced to give up work due to her vomiting.

Ms Warnes said: ‘Now I can do normal things like go to the shops, take [my daughter] to nursery and just be a mum. Beforehand I was just being sick or waiting around to be sick. I was just knackered.

‘People will say “Oh she just wants to be a druggie” but it’s not that at all. I don’t get high off it. It’s a couple of puffs with a minimum bit of baccy.’

Ms Warnes said she chose not to tell a midwife about the smoking, as she knew they would give her ‘stick’.

She was previously prescribed Domperidone, used to relieve nausea and vomiting, but claims it would only get rid of her symptoms for 20 minutes at a time.

Ms Warnes, who is expecting her baby with partner Gav, 32, in May 2020, said: ‘I’m not abusing it or trying to get blazed.

‘Some days I have good days and don’t need it. Other days I am throwing my guts up and need a couple of puffs.

‘I got some a few days later and as soon as I took it the symptoms just went away. It wasn’t just a case of me feeling sick the whole time. I couldn’t do anything at all.’

She added: ‘It was to medicate my body, not to get stoned.’

As many as eight in every ten women experiencing morning sickness as a side effect of pregnancy, with symptoms most commonly improving or disappearing around 14 weeks.

However, those who experience hyperemesis gravidarum, similarly to Kate, the Duchess of Cambridge, can see symptoms last for half of their pregnancy.

NHS guidelines advise those who experience severe symptoms to contact their midwife, doctor or hospital to seek treatment.