 This is the VOA Special English Health Report. A miscarriage is the natural loss of a baby before the 20th week of pregnancy. Experts say many pregnancies end before a woman even knows she was pregnant. Up to 20% of known pregnancies end in a miscarriage. Miscarriages are generally caused by genetic problems with the baby that prevent it from developing. But whatever the cause, the loss of a pregnancy can be heartbreaking. And sometimes the advice that women receive after a miscarriage can also be heartbreaking. Some women are told to wait before they try to get pregnant again. A 2005 report from the World Health Organization advised waiting at least six months. Some doctors advise women to wait even longer. But a Scottish study published in 2010 found no need to delay. Researchers from the University of Aberdeen examined the medical records of 30,000 women. The women visited Scottish hospitals between 1981 and 2000. They had miscarriages in their first known pregnancies and became pregnant again. The study found that 85% of women who waited less than six months to get pregnant had live births. That compared to 73% of women who waited more than two years. Those who quickly became pregnant again were less likely to have a dangerous pregnancy form in their fallopian tubes. They were less likely to lose their fetus after 20 weeks known as a stillbirth. They were also less likely to give birth by caesarean section. And they had fewer preterm births and fewer babies with low birth weight. The study found that about 40% of women became pregnant again within six months. 25% got pregnant within six to twelve months. The women who quickly became pregnant again after a miscarriage were more likely to be older. Older women might be less likely to delay because they know there are more risks with pregnancy, the older they get. The 2010 report appeared in the BMJ, the British Medical Journal. The researchers pointed out that their results were limited to Scottish records and could not be generalized to all women. For example, women in developing countries start having children at an earlier age than females in western countries. For VOA Special English, I'm Mario Ritter. Find us online at voaspatialenglish.com.