Health Report.A miscarriage is the natural loss of a pregnancy before the twentieth week. This happens to as many as twenty percent of known pregnancies.Experts say many pregnancies end before a woman even knows she was pregnant.Miscarriages are usually caused by chromosome problems that prevent the baby from developing. The online medical encyclopedia MedlinePlus says these problems are usually unrelated to the genes of either parent.But whatever the reason, the loss of a pregnancy can be heartbreaking. And sometimes the advice that follows can be painful, too.Some women are told to wait before trying to get pregnant again. A two thousand five report from the World Health Organization advised waiting at least six months. Some doctors advise a longer wait.But a new study from the University of Aberdeen in Scotland found no need to delay. Researchers examined the medical records of thirty thousand women. These women visited Scottish hospitals from nineteen eighty-one to two thousand.They had miscarriages in their first known pregnancies and became pregnant again.The study found that eighty-five percent of women who waited less than six months to get pregnant had live births. That was compared to seventy-three percent of women who waited more than two years.Those who quickly became pregnant again were also less likely to have a pregnancy form in their fallopian tubes, a dangerous condition. And they were less likely to have a stillbirth, the loss of a fetus after twenty weeks.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 report appears in BMJ, formerly the British Medical Journal.The study found that about forty percent of women became pregnant again within six months. Twenty-five percent got pregnant within six to twelve months.But the researchers point out that their results are limited to Scottish records and cannot be generalized to all women.For example, compared to Western countries, women in developing countries start having children at an earlier age.The Scottish 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 that the older they get, the higher the risks.And that's the VOA Special EnglishHealth Report, written by Caty Weaver. You can find our reports at 51voa.com and on Facebook and Twitter at VOA Learning English.