How long can you wait to have a baby? Apparently longer than most women think. The long-ingrained fear of age-induced infertility - that women will not be able to conceive if they wait too long - is actually based on science that dates back to the 17th Century. The widely-accepted notion that 30per cent of women aged 35 to 39 will fail to fall pregnant is based on a 2004 article published in the journal, Human Reproduction, according to The Atlantic. However the source of that data actually comes from French birth records between 1670 and 1830. It seems that studies of natural fertility in females have rarely included women born in the 20th century. Instead, the reported decline in fertility over the course of a woman’s Thirties has been based on statistics from a time when electricity was yet to be invented. Indeed, a more recent study, conducted in 2004 and published in Obstetrics & Gynecology, actually shows that women over 35 have an 82per cent chance of getting pregnant within a year. 'In our data, we’re not seeing huge drops until age 40,' explained Anne Steiner, an associate professor at the University of North Carolina. 'In short, the “baby panic” is based largely on questionable data,' writes The Atlantic's Jean Twenge. Ms Twenge also notes that studies of natural conception, regardless of age, are difficult to conduct and therefore, modern fertility statistics are under represented. 'Studies asking couples how long it took them to conceive or how long they have been trying to get pregnant are as unreliable as human memory,' she explains. 'And finding and studying women who are trying to get pregnant is challenging, as there’s such a narrow window between when they start trying and when some will succeed.' Unfortunately, fertility clinicians stand to benefit financially from women's heightened fear of infertility. The deeper anxiety women feel, the more likely they are to agree to expensive treatments, like in vitro fertilization -- which could be one explanation of doctors' widely cited infertility statistics that appear to be being oversold. Article: 21st June 2013 www.dailymail.co.uk