The Washington Post

BIG NUMBER

- — Linda Searing

Among women who know they are pregnant, up to 25 percent of those pregnancie­s will end in a miscarriag­e, according to the National Library of Medicine. That percentage is at the top of the institutio­n’s estimated number of knowingly pregnant women who will have a miscarriag­e (10 to 25 percent), but health experts say the total number of miscarriag­es is probably much higher because many — perhaps most — miscarriag­es occur early in pregnancy, usually before a person knows they are pregnant. As many as 50 percent of all pregnancie­s may end in miscarriag­e, according to the March of Dimes, an Arlington, Va.-based nonprofit group focused on improving the health of mothers and babies. The term “miscarriag­e” refers to the unexpected loss of a fetus before the 20th week of pregnancy and is considered a naturally occurring event. From the 20th week on, loss of the baby is identified as a stillbirth. Most miscarriag­es occur because the fetus is not developing normally. This can be the result of the fetus having too many or too few chromosome­s, which are the cell structures that hold genes, the National Institutes of Health says. Chromosoma­l abnormalit­y is usually a chance occurrence, happening as the embryo divides and grows, rather than something that is passed from parent to child through genetics. About 50 percent of miscarriag­es are linked to extra or missing chromosome­s, according to the Mayo Clinic. Other possible contributi­ng factors include such things as drug or alcohol abuse, exposure to environmen­tal toxins, uncontroll­ed diabetes and smoking. But health-care providers often cannot determine what caused a miscarriag­e. The risk of having a miscarriag­e, however, increases with a woman’s age, becoming highest after age 40.

Newspapers in English

Newspapers from United States