Fetal heart stress after maternal COVID-19 vaccination

Why is no one talking about this?

Most of us have heard that the COVID-19 vaccines can cause adverse heart effects, like myocarditis. However, there’s been little discussion of whether they can affect the hearts of unborn fetuses when their mothers get vaccinated.

This is unfortunate, because there’s evidence that they can.

Cases of fetal tachycardia (elevated heart rate)

Let’s first look at some case reports: Fetal supraventricular tachycardia and maternal COVID-19 vaccination: is there any relationship?

This paper describes two pregnant women whose babies experienced “tachycardia,” which is an elevated heart rate, after receiving the Pfizer vaccine.

Case 1

A 27-year-old woman went for a routine ultrasound at week 31 of pregnancy and discovered that her baby had an elevated heart rate, aka “tachycardia,” at 220 bpm.¹

Her pregnancy course had been “uneventful apart Pfizer-BioNTech COVID-19 vaccination at 14⁺⁴ weeks and 17⁺⁴ weeks first and second dose respectively.”

The baby had a “structurally normal heart,” but had “minimal pericardial effusion,” or swelling of the heart. This happens because of a buildup of extra fluid around the heart; it’s usually a sign of some kind of inflammation.

Image from here.

There was no history of fever, excessive caffeine consumption, or other obvious causes for the heart issues.

A heart medication, digoxin, was prescribed. The baby was born at week 38. At birth, he appeared to have a normal heart rate, though he was given another heart medication (amiodarone) for 6 months.

Case 2

A 34-year-old female had received her first Pfizer-BioNTech COVID-19 vaccine at 27 weeks of pregnancy. She went for a routine ultrasound at 29 weeks to discover that her baby had an elevated heart rate of 230 bpm. She was given the heart medication digoxin.

Despite this, the patient got her second dose of the Pfizer vaccine, at 31 weeks. Two weeks later, at 33 weeks, the baby was born prematurely.

The woman did have high blood pressure and gestational diabetes, which could have contributed to the preterm birth, though the authors of the case report state that “we cannot eliminate the impact of the vaccine in the induction of spontaneous preterm labor.”

The baby had a “structurally normal heart” and normal heart rate at birth, though arrhythmia (irregular heart beat) occurred 4 days after birth. The baby was given more heart drugs for 6 months.

Fetal heart swelling coinciding with the shots

Next let’s look at this study, which looked for pericardial effusion (heart swelling), in unborn babies: Fetal pericardial effusion after maternal COVID-19 vaccination: a fortuitous association?

This was a retrospective study from a Fetal Cardiology department at a hospital in northeast Brazil. They reviewed over 10,000 echocardiograms of pregnant women referred to their unit between September 2019 and August 2021.²

They found that a “much higher incidence of pericardial effusion without structural heart disease was observed during the months of June, July, and August 2021” and this “coincided with the immunization of pregnant women, which started in May 2021 in our city.”

The increase in isolated pericardial effusion coincided with the period of massive COVID-19 immunization.

An example of an echocardiogram showing heart swelling in a 30-week-old fetus

They hypothesized that the fetal heart swelling (pericardial effusion) “could reflect a fetal inflammatory response to the transferred antibodies from the maternal immunization process.”

Remarkably, they then said this “could mean that the fetuses were being effectively immunized in-utero.”

This would be reassuring; however, further studies are needed to determine if such a causal relationship exists and its potential mid- to long-term implications, or if our findings were simply a fortuitous association.

So maybe the fetuses are getting antibodies, but their hearts are stressed as a result. Yes, “further studies are needed.”

Some takeaways

• Of course, we don’t know for certain whether the vaccine caused the fetal heart issues in any of these cases. They could be coincidences.

• In the case reports, the women didn’t discover the fetal heart issues till they went in for routine ultrasounds. This highlights how women may not know that something is wrong until they go in for a checkup.

• In the first case, the woman had gotten her second shot at week 17 of pregnancy, and discovered the tachycardia at week 29 when she went for a routine checkup. If the shot led to the tachycardia, that probably means the baby was experiencing heart stress for many weeks.

• For every pregnant woman who discovers tachycardia in her baby, there may be many more whose babies only experience tachycardia for a short period of time, and therefore go undetected.

• In the second case, the woman got a second shot despite the fact that her baby’s tachycardia seemed to coincide with administration of the vaccine. No one even thought to think that the vaccine could have caused the issue.

• We don’t know whether the fetal heart issues were due to some response that the mother was experiencing, or whether there was some kind of transfer of vaccine or spike protein to the fetuses. We have no idea, because it hasn’t been adequately studied.

• We don’t have any long term follow-up of these babies. We don’t know whether their heart stress during gestation sets them up for weaker hearts down the road. Someone should track these children. I doubt anyone will though.

1. There isn’t a clear cut-off for what a “normal” fetal heart rate should be, but it’s probably somewhere in the range of 110-160 bpm. So 220 bpm, is highly elevated.

2. They looked at echocardiograms from 10,551 pregnancies. Only first-time exams were reviewed. It’s therefore likely that they didn’t detect all the pericardial effusions from all these pregnancies. Also the echocardiograms were not performed on women with known COVID-19 infection.