The ruling has been introduced by the Peninsula Health Technology Commissioning Group, which regulates the region’s NHS fertility treatment.
Group chairman Dr Virginia Pearson said there was a link between smoking, weight and the success of treatment.
But Dr Andy Sant, of Devon Local Medical Council, expressed concern over a “rationing” of the service.
According to the regulations, both men and women must not have smoked within the previous six months and must have a Body Mass Index of between 19 and 29.9 to be eligible for certain fertility drugs.
Dr Virginia Pearson said: “There is sound evidence that being significantly over or underweight can reduce fertility.
“Smoking may reduce fertility in women, while for men, there is a link between smoking and poorer quality of sperm.
“Smoking is also a risk to the baby, smoking exposes the unborn baby to the toxins in tobacco smoke, and can damage the placenta.”
She added that babies born to mothers who smoked had an increased risk of low birthweight, poorer lung function and were twice as likely to die from cot death.
But Dr Sant, vice-chair of the medical council and a Plymouth clinician, said: “Everybody has their own individual circumstances and it may be that often a six-month ban on smoking is unreasonable.
“The second issue is about rationing in the health service. Rationing is almost certainly happening but the debate needs to be in the public.”
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