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Miscarriage and pregnancy loss: causes, treatment and research

What causes miscarriage and pregnancy loss, and can it be treated? We look at the latest medical research.

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While research into what causes miscarriage and stillbirth is gaining momentum around the world, the cruel truth is that for most pregnancy losses, a simple explanation will never be uncovered.

Statistically, one in four pregnancies ends in miscarriage—often before a woman even knows she is pregnant. “They can just have a heavy period that they don’t realize is a miscarriage,” says Liisa Honey, Chief of Obstetrics and Gynaecology and director of the maternal newborn program at Queensway-Carleton Hospital in Ottawa. “Most of the time there’s no good reason. It’s not what you ate, it’s not the activity you did, it’s not the sex you had the night before. Women are always looking to blame themselves—‘Oh, it’s that glass of wine I had two weeks ago.’ But the most common reason is a genetic aberration. The body has recognized that it isn’t a viable pregnancy.” She offers some hope, in the form of another statistic: “The most important thing is for women to stop blaming themselves. The likelihood of them going on to have a normal pregnancy is 75 percent.”

After three losses, doctors recommend seeking medical attention to rule out causes of recurrent miscarriages. “By the time you’ve had three, the stats are suggesting that this is no longer a random event. It may be, but it’s important to follow up with your doctor for further investigation,” says Honey.

This process typically begins with ruling out genetic abnormalities with both parents, and infections such as chlamydia or gonorrhea, which can harm pregnancies. Endocrine issues, such as uncontrolled diabetes and thyroid problems (which also affect the body’s ability to produce hormones), must be ruled out. Doctors will also look at hormonal abnormalities and check for “structural causes,” such as fibroids or polyps in the uterus.

Only one in about 50 women who have three losses in their first trimester will find a “significant, treatable, underlying cause,” says John Kingdom, chair of Obstetrics and Gynaecology at the University of Toronto and director of the world-renowned Placenta Clinic at Mount Sinai Hospital. However, women who lose a baby and then conceive again with the same partner within a year have a decreased risk of suffering problems traced to the placenta, the organ that nourishes the fetus throughout. “The first pregnancy is priming the uterine cavity,” Kingdom explains. “So a miscarriage isn’t necessarily a disaster. It could actually mean that the next time you get pregnant, you’ll do better than you would have the first time around.”

It is crucial, Kingdom says, to enter pregnancy as healthy as possible. “The demography of women having babies today is relentlessly increasing the risk of loss. People are older, they’re heavier, and they’re delaying pregnancy.” Kingdom also points out that stillbirth and miscarriage rates are on the rise in western countries. This is because the rate of a risk of miscarriage increases with maternal age, and commonly available over-the-counter pregnancy tests are allowing women to find out they’re pregnant much earlier (often before six weeks). Therefore, more women know they’re pregnant sooner and will notice if there’s a loss.


While most miscarriages happen in the first 12 weeks of pregnancy, it’s important to know that passing the first trimester doesn’t reduce risk of a loss to zero. “One of the biggest myths around pregnancy is you get to the three-month mark and you’re good,” says Christie Lockhart, a midwife who has suffered two miscarriages. “People who have had full-term stillbirths or later losses will tell you there is no safe point,” says Lockhart.

Honey tells her patients that although risk of a loss is rare after 12 or 14 weeks’ gestation, “I would never say you’re safe. Risk of loss is markedly reduced.”

Currently, there are no treatments proven to prevent run-of-the-mill miscarriages, or “unexplained losses” that doctors can’t trace to an underlying condition. “It’s usually a chromosomal abnormality, an error of mother nature or bad luck,” says Nicole Racette, acting head of Obstetrics and Gynaecology at BC Women’s Hospital & Health Centre. “It can happen over and over again. And adding medication doesn’t help.”


But there are some promising options that can reduce risk of tragic, late-term losses. Several recent studies have shown low-dose aspirin taken daily before 16 weeks of pregnancy decreases the risk of pre-eclampsia, a rare condition that can be fatal to both baby and mother, and that’s traced to placental dysfunction. Heparin, a drug commonly used to prevent blood clotting, has also shown promise in reducing the risk of severe pre-eclampsia, although not because of its anticoagulant properties, Kingdom said. In basic terms, Heparin promotes the growth of healthier blood vessels and can enable placental tissue—and thus the fetus—to grow well.

In Toronto, much of the research underway at Kingdom’s lab is devoted to developing a routine early detection test that would flag mothers at high risk of late-term loss or stillbirth. Most stillborn babies, Kingdom says, are “structurally normal” and would have been born alive had they been delivered weeks earlier. Their deaths, he says, are typically due to some form of undetected placental disease. “We should try and find and rescue those babies earlier, to prevent them being stillborn,” he says, as long as they are older than 30 weeks and they weigh more than 1 kilogram. (There have been great advances in NICU care.)

“Just because we don’t have some fancy drug doesn’t mean we can’t do a lot of good things to help people have healthier pregnancies,” says Kingdom.

Miscarriage and pregnancy loss: causes, treatment and research
This article was originally published on May 14, 2014

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