Fat chance Being even slightly overweight can significantly increase the risk of heart failure, just as moderate exercise - even as little as once a month - can significantly reduce it. These are the key findings of a 20-year US health study of more than 21,000 doctors. Their risk of heart failure rose by 11 per cent for every 3.2kg of excess body weight, and up to 180 per cent for those defined as obese (a body-mass index of 30 or more), Reuters reports. '[But] even if somebody exercised [vigorously] one to three times per month, they had an 18 per cent reduction in the risk,' says researcher Satish Kenchaiah of Boston's Brigham and Women's Hospital. Constant craving Women may find it tougher than men to give up smoking, with US researchers saying they appear to suffer more intense withdrawal symptoms such as depression, anxiety, poor concentration and weight gain. The Mayo Clinic team didn't provide details of the study, and said there's no evidence men are more successful at quitting. But they note that women typically gain up to 4.5kg during withdrawal, which can cause enough stress to make them start smoking again, healthday.com reports. Most people require four to six attempts before succeeding, says team leader Patrick Draper. Passive resistance Women exposed for long periods to second-hand smoke, even as children, appear to have much more trouble falling pregnant and are at greater risk of miscarriage or stillbirth, say University of Rochester researchers, based on a study of more than 4,800 women between 1982 and 1998. The risks rose with the number of hours' exposure a day, but on average those affected were 68 per cent more likely to have trouble conceiving and 39 per cent more likely to suffer a miscarriage or stillbirth, Reuters reports. Shedding light on Caesareans Pregnant women with low levels of vitamin D appear to be significantly more likely to have a Caesarean delivery, say Boston University researchers, based on a small two-year study. The reasons aren't clear, but team leader Michael Holick says previous studies have linked vitamin D deficiency with muscle weakness. More than 250 women were involved in the study; those deficient in vitamin D, which is naturally produced when the body is exposed to direct sunlight, were almost four times more likely to have a Caesarean, healthday.com reports. Mind blowing Merely thinking about sex causes some people to sneeze - in some cases uncontrollably - says a report in the Journal of the Royal Society of Medicine. The study is based on historical reports and an internet search that came up with 17 men and women who say they sneeze whenever they think about sex and three who do so when they orgasm, WebMD reports. Team leader Mahmood Bhutta, an ear-nose-and-throat specialist at Wexham Park Hospital, suggests some connection with the body's subconscious nervous system. Utterly incensed Austria has joined Switzerland in banning the sale of an exotic herbal incense that has become popular because of its hallucinogenic effects. The incense, which has been found to contain a cannabis-like substance called JWH-018, is sold under such names as Spice Gold, Spice Tropical Synergy and Spice Yucatan Fire. The Spice range has been banned in Switzerland since the end of last year. Austria has now imposed a 14-day ban, pending further investigation, AFP reports.