Women should give up vaping if they are hoping to get pregnant, according to a study that suggests it may affect fertility. In the first research to demonstrate a link between fertility prospects and electronic cigarettes across a large population, analysis of blood samples from 8,340 women revealed that people who vape or smoke tobacco had lower levels of anti-Müllerian hormone (AMH), which indicates how many eggs women have left in their ovaries. The study found that across all age groups AMH levels were lower in people who vaped than non-vapers. Nearly a quarter of those trying to conceive said they regularly or occasionally vaped, according to the report by the women’s health firm Hertility based on data from 325,000 women, mostly in their 20s and 30s. The study was conducted in the UK and was based on analysis of anonymised data. The study’s author, Dr Helen O’Neill, a lecturer in reproductive and molecular genetics at University College London and the chief executive of Hertility, said women should be advised to quit the habit to avoid thwarting their chances of getting pregnant. She said women planning to get pregnant should be given clear guidance of “no drinking, no vaping, no smoking, no drugs”, the Times reported. O’Neill said: “This is the first piece of evidence to show a link between fertility and vaping across a large population. It shows that AMH is suppressed in vapers compared to non-vapers, in a similar way to what has already been shown in smokers. AMH is a hormone used to assess ovarian [egg] reserve, and therefore fertility.” The report, which analysed the lifestyle habits of women in the months before getting pregnant, also found that 7% admitted to taking recreational drugs and 40% said they consumed alcohol weekly. O’Neill said: “Trying to drink in moderation can be a slippery slope when it comes to volumes and intake of wine or alcohol in a week. The best advice is to stop, as opposed to cutting down or trying in moderation.” There are growing concerns about rising nicotine addiction in young children. Last month the government passed a law to ban smoking for anyone born after 2009, and it is also introducing new restrictions on vapes including banning the sale and supply of disposable vapes under environmental legislation. Earlier this week a study suggested that girls aged 13 and 15 in Great Britain drink, smoke and vape more than boys. The World Health Organization research in 44 countries found that two-fifths of girls in England and Scotland had vaped by age 15 – a higher proportion than in other countries such as France, Germany and Spain. Researchers also found that 30% of 15-year-old girls and 17% of 15-year-old boys in England had vaped in the past 30 days, which was higher than children in several other countries including Ireland, Canada and Spain. The study found girls were more likely to have used a vape by 15 than the average for all 44 countries studied, with vaping having now overtaken smoking. Last week a report said children addicted to vaping should be given nicotine patches or gum to help them break their habit. Public Health Wales, one of the organisations that makes up NHS Wales, said vaping should be seen as a “dependency issue” rather than a deliberate act of misconduct, with young people needing support to quit.