Blood thinner used by pregnant moms is ineffective: Canadian study
WATCH: Thousands of pregnant women across the country inject themselves with blood thinners they were told could prevent a miscarriage. It’s been a common practice for the last two decades, but a new landmark study out of Ottawa says for many of those women, the injections were totally unnecessary. Vassy Kapelos reports.
Some expectant moms give themselves a daily dose of blood thinners if they’re at risk of developing blood clots. But a new Canadian study is warning that the treatment is ineffective.
Ottawa Hospital researchers say that the treatment might even lead to some minor harm in pregnant moms because of increasing bleeding, increasing rates of induced labour and reducing access to anesthesia during delivery.
The blood thinner – a daily dose of anticoagulant low molecular weight heparin or LMWH – is also administered via needle injection. The doctors call it “painful and demoralizing.” Over the course of a woman’s pregnancy, she’d be injecting herself with hundreds of needles, causing bruising and pain around her belly.
“These results mean that many women around the world can save themselves a lot of unnecessary pain during pregnancy,” Dr. Marc Rodger, a senior scientist at the Ottawa Hospital, said.
“Using low molecular weight heparin unnecessarily medicalizes a woman’s pregnancy and is costly,” he said.
About one in 10 pregnant moms have a tendency to develop blood clots in their veins. The condition’s called thrombophilia.
For the past two decades, doctors have prescribed these women at risk a daily dose of LMWH in an attempt to stave off a string of complications. At that time, researchers noticed a link between pregnancy complications and blood clots in the placenta.
Blood thinners became the response to discovering this link.
“It’s very emotional to have a pregnancy and a loss or experience one of these other complications,” Rodger told Global News.
“This looked like something that would hold great promise and just based on that hope, a lot of women demanded it and a lot of physicians prescribed it,” he said.
LMWH is commonly doled out to expectant moms to fight placenta blood clots, high blood pressure, heavy bleeding and the potential for having a low-weight baby. The blood thinner is also used to help with leg vein blood clots and lung blood clots.
But Rodger suggests that move was made without any large, clinical trials to measure the treatment’s efficacy in pregnant moms. So he sought to conduct a trial himself.
“While I wish we could have shown that LMWH prevents complications, we actually proved it doesn’t help. However, I’m very glad that we can now spare these women all those unnecessary needles,” Rodger said.
His clinical trial spanned 12 years and looked at 292 women at 36 hospitals in five countries. The women were at an additional risk of blood clotting, had complications in previous pregnancies or they had a family history of blood clotting.
What took the trial so long was the recruitment process. Women had “very clear notions” about the blood thinners or they were against giving themselves a daily needle, Rodger told Global News.
In the trial, about 17 per cent of the women encountered a serious complication, but there wasn’t a difference between those assigned the blood thinners and those who weren’t.
Ultimately, Rodger hopes his findings will dissuade doctors from using common blood thinners on pregnant women.
Instead, they may be able to focus their efforts on other treatments or zero in on segments of the pregnant population to help physicians decide who may be the best candidate.
Pfizer, for its part, says that it stands by its LMWH drug – called Fragmin – that’s been approved in Canada to help with blood clotting.
“Pfizer believes in clinical research and the value that the outcomes bring to improving patient care,” the company said in a statement to Global News.
In its press release, the Ottawa Hospital refers to Canadian women who relied on LMHW injections to help them through their pregnancies.
In one case, a 34-year-old Ottawa lawyer spent 2.5 months self-administering a needle every day. The treatment didn’t work, and she miscarried three times.
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“It was difficult after realizing the injections didn’t work,” Allison McIntosh said in a statement.
“I thought that I was doing something to make a difference by giving myself the injections. I kind of lose hope after that experience.”
McIntosh is pregnant for a fourth time and this time around, she’s ditching the LMWH injections.
“I feel sad for other people who are going through that process. It can be disillusioning for people if those injections are their only hope,” she said.
Rodger’s full findings were published Thursday night in the journal The Lancet.
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