Almost no one sees a miscarriage coming. And for couples who've struggled to become parents, losing their baby-to-be may be even harder to bear, bringing with it questions, fear, and heartbreak.
Miscarriage was the last thing on the mind of Suzanne, a Boston executive, when she got pregnant for the second time three years ago. Her first pregnancy had gone smoothly, she had no trouble conceiving, and she felt great. When she was 10 weeks pregnant, Suzanne had her first prenatal appointment. She looked forward to hearing the thrilling whoosh-whoosh-whoosh of her baby’s heart.
But when the nurse practitioner listened, she heard nothing. “At that point there should have been a strong heartbeat,” says Suzanne. “When I looked at her face, I knew.” An ultrasound confirmed it: Suzanne had experienced a miscarriage.
Suzanne, now 35, was shocked—she thought miscarriage was something that happened to other people. “I had given very little thought to the possibility of something going wrong. It really pulled the rug out from under me.”
Like many women, Suzanne had no idea how common miscarriages are. In the United States, 15 percent to 25 percent of recognized pregnancies—more than a million a year—end in miscarriage. “It’s an astoundingly large number—one that most women do not learn until they are sitting in a paper gown in their obstetrician’s office, hearing the heartbreaking news about their pregnancy loss for the first time,” says Bruce K. Young, MD, professor of ob/gyn at New York University Langone Medical Center and author of the book, Miscarriage, Medicine & Miracles: Everything You Need to Know About Miscarriage (Dell, 2008).
The number of miscarriages is even higher if you take into account the “unrecognized” pregnancies that occur when a fertilized egg fails to implant in the uterus. These pregnancies are considered unrecognized because they usually happen before a woman realizes she’s pregnant and result in bleeding around the time of her next period. According to the March of Dimes, adding in those early losses pushes the miscarriage rate to 50 percent of pregnancies.
The good news is that although first miscarriages are common, second, third, and fourth miscarriages are not. “The likelihood of having two successive miscarriages is less than 5 percent, and the majority of women who have had a miscarriage go on to have healthy pregnancies,” says Christine C. Skiadas, MD, a clinical fellow in reproductive endocrinology and infertility at Brigham and Women’s Hospital in Boston.
Among those couples who do have repeated miscarriages, medical treatment can often correct the physiological or genetic problems that stand in the way of a successful pregnancy. “Even after three miscarriages, there is still a 72 percent likelihood of a term pregnancy and a healthy baby the next time you try,” Dr. Young says.
Why Do Miscarriages Happen?
One of the first questions couples ask themselves after a miscarriage is “why?” Usually, the answer is “genetics.” Up to 70 percent of miscarriages are caused by genetic error in the fetus. These abnormalities occur when the sperm or egg is defective, when cells don't divide normally, or when a gene contains the wrong number of chromosomes. Genetic defects occur more often in aging sperm and eggs, which is why the risk of miscarriage increases with age. After age 40, more than one-third of recognized pregnancies end in miscarriage, according to the American Society for Reproductive Medicine.
Some other, less common causes of miscarriages include bacteria (listeria or brucella) or viruses (chicken pox, rubella, parvovirus B19). For example, one study found that bacterial vaginosis, a common vaginal infection, makes a woman nine times more likely to miscarry. A woman may also have a hormone imbalance, such as too little progesterone or thyroid hormone, or an immune system disorder, such as antibodies that cause blood clots in the placenta. Anatomical abnormalies in the uterus, fallopian tubes, or cervix can also lead to miscarriage, as can dangerous lifestyle factors, including cigarette smoking, heavy alcohol and illegal drug use, and exposure to toxic chemicals such as industrial solvents. Major trauma from a serious car accident, physical abuse, or a fall can cause a miscarriage, and prenatal tests such as amniocentesis and chorionic villus sampling (CVS) raise miscarriage risk slightly, to 1 in 370 procedures for amnio and 1 in 360 for CVS.
Despite what you may hear from your mother-in-law or read online, miscarriage in healthy women is not caused by exercise, having sex, climbing ladders, flying on airplanes, seeing something frightening, lifting heavy objects, being in a bad mood, or working. Researchers are studying whether there is a connection between stress and miscarriage, but most doctors see no link. “The reality is, during World War II, when people were being starved and brutalized, they still had babies,” Dr. Young says. “Women in prisons get pregnant and have babies. And after 9/11, studies showed no increase in miscarriages.”
After the second trimester begins, miscarriage risk drops sharply—95 percent of miscarriages occur during the first 13 weeks of pregnancy.
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