Smoking cannabis during pregnancy is even more dangerous than normal cigarettes, experts have claimed.

While it is widely accepted that smoking or taking drugs while pregnant poses a risk to the unborn child, many mums-to-be see cannabis as a safer option than other substances. In the US, it is estimated that between two and 11 per cent of pregnant women smoke cannabis.

However, using cannabis increases the risk of babies being born premature or with a low birth weight, according to a new study published in the American Journal of Obstetrics and Gynecology.

Dr Diana Racusin, based at the Baylor College of Medicine in Houston, Texas, said: “We are only now beginning to learn about the ramifications of marijuana use in pregnancy.”

Researchers studied the medical records of 12,069 women, all of whom gave birth between January 2011 and June 2015. They had all been quizzed about their use of cannabis and tobacco as well as any other products containing nicotine.

Out of the study group, 106 of the expectant mums had used cannabis during pregnancy. And of these women, 48 also smoked standard cigarettes.

Drug use raises risk of premature birth

In the group of women who smoked both cannabis and cigarettes, the research team noticed more early deliveries and small babies, which increases the risk of other health problems and difficulties with feeding.

Smoking both cannabis and tobacco meant women were more than twice as likely to give birth prematurely than those who steered clear of the substances and the risk of their babies having a small head and low birth weight was almost tripled.

Smoking cannabis and tobacco also more than doubled the risk of developing asthma. And those who smoked both substances were two and a half times more likely to suffer from pregnancy-related hypertension.

In the UK, pregnant women are asked about their drug use as well as whether they smoke or drink alcohol during an appointment with a midwife. Women who misuse substances may be referred to a specialist team for extra support.

Drugs tests are not routinely carried out on pregnant women but may be used in some circumstances where an expectant mum is known to have a history of substance misuse.

AlphaBiolabs also sells peace of mind drug tests which can be used by family members who are concerned a loved one may be abusing illegal substances.