Want more Inside Medicine? Get it in your inbox first thing and stay ahead! Click here to subscribe.
A new study published in the New England Journal of Medicine reports that pregnant women who had recently received a Covid-19 vaccine did not have higher odds of a miscarriage compared to unvaccinated controls who were also pregnant at the same time.
Pregnant women are often excluded from clinical trials, including ones that studied the Covid-19 mRNA vaccines by Pfizer and Moderna. Because pregnant women are often not studied in clinical trials, it takes longer for experts to be able to confidently say that a medicine or vaccine is safe for them.
But during the Covid-19 pandemic, many of what scientists call “natural experiments” have occurred. In this case, thousands of women in Norway received a Covid-19 vaccine before they were aware of being pregnant. (Some others were aware of being pregnant but had chosen to be vaccinated because of important risk factors). This gave scientists the opportunity to compare first-trimester miscarriage rates among women who had received a Covid-19 vaccine in the previous 3 or 5 weeks to those who had not been vaccinated during that time. The rates were the same and similar to those normally detected by researchers, which hovers between 10-25%.
Many people are surprised that miscarriage rates are that high in general. But the reality is that many early pregnancies end in miscarriage (or “spontaneous abortion,” another medical term for a miscarriage) that go undetected. Frequently, early pregnancies that end in miscarriage are attributed to a “late period.” The earlier a pregnancy is, the higher the odds of a miscarriage are.
Several previous studies have also found no link between the Covid-19 vaccines and miscarriage rates. But this particular study leveraged Norway’s national databases that report on 1st trimester pregnancies, Covid-19 vaccination status, and other demographic features. This allowed the research scientists to compare pregnant women who had been recently vaccinated to those who had not been vaccinated. This type of study is called a “case-control,” and while it is not quite as informative as a truly randomized trial in which some participants are selected to receive a treatment or vaccine and others are not, it is considered a reliable study design for questions of this nature.
This new research should re-assure women who are pregnant and wondering about whether the Covid-19 vaccines are safe. They are. The last thing a pregnant person wants to do is anything that could be risky to their body or their pregnancy. The good news is that, yet again, scientists have found that vaccinating against Covid-19 is safe (and also, as I’ll discuss in a moment, highly beneficial).
A great deal of false information on this topic has circulated online and elsewhere. But what misinformation dealers tend to leave out when they are spreading false fears about Covid-19 vaccines, is that Covid-19 itself poses a significant threat to pregnant women and to their fetuses and eventual infants. Pregnant women with Covid-19 have been found to have far higher rates of serious complications and mortality. One study found that the maternal mortality rate among women who had Covid-19 during their pregnancy was 22 times higher than normal rates, rising to 1.6% (or 1 in 63, up from the normal rate of 1 in around 1,375).
While viral transmission to a fetus during pregnancy appears to be unusual, Covid-19’s effects on the mother are substantial enough that their newly born infants have been noted to more frequently be born with low birth weights and with other signs of distress. Even worse are the number of motherless babies due to Covid-19 mortality, tragedies that we can now avoid with vaccines.
The bottom line is that Covid-19 vaccines appear to have no link with miscarriages and that Covid-19 itself remains a genuine threat to pregnant women and their fetuses and eventual infants. The American College of Obstetricians and Gynecologists already recommends Covid-19 vaccines for pregnant women. In addition, recent research also shows that pregnant women who were recently vaccinated against Covid-19 pass high levels of protective antibodies to their infants, meaning that the babies of vaccinated mothers are likely to have some built-in protection against Covid-19, at least for some period of time. That’s important because currently, the Covid-19 vaccine trials are assessing outcomes of babies 6 months and older. That means that vaccinated mothers may be able to “bridge the antibody gap” by getting vaccinated during pregnancy.
So, while many people continue to ask whether pregnant women be vaccinated against Covid-19 (the answer is a resounding yes), the real question should be when? Hopefully, data answering this question will soon emerge.
Subscribers can add your questions and comments below (Click here to subscribe for free). I’ll try to answer as many as I can and bring in expert advice from colleagues if needed.
Also, select any text above to easily share a quote on a variety of social media platforms! Let's get reliable information out there and drown out the misinformation.