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24. November 2021

Covid vaccinations in the first 13 weeks of pregnancy: increased miscarriage rate???

Urgent request to all fertility centers to verify and hopefully disprove this!

In this blog, I would like to address a medical study that reportedly concludes that Covid vaccinations in pregnancy do not pose an increased risk to the embryo.

The study was published in June 2021 in the New England Journal of Medicine (NEJM), one of the most prestigious medical journals. The title of the article is:

Preliminary Findings of mRNA Covid-19 Vaccine Safety in Pregnant Persons

In the abstract, the study concludes that there were no ‘obvious safety signals’ after mRNA vaccinations in pregnancy.

The original study can be downloaded here:

Data were collected by telephone and smartphone. Mainly women from the health sector participated. The first vaccination took place between 12/14/2020 and 02/28/2021. ‘As of March 30, 2021’, participants were contacted. The follow-up period is expected to last twelve months (p. 2274 top right) after the last vaccine dose and three months after the babies are born. However, there was not much time to contact and follow up the pregnancies, as the first publication of the study already took place on 04-21-2021 (outlined with yellow):

Regarding the results that I am questioning: In table 4 (page 2280), the authors illustrate that the miscarriage rate before the 20th week of pregnancy (marked in yellow). corresponds to the normal miscarriage rate of about 13% (colored in turquoise). However, the small print below the table depict how the authors arrive at these figures:


– The 827 participating patients marked in green had been vaccinated and reported a completed pregnancy. The authors refer to a completed pregnancy as a pregnancy that was terminated by miscarriage, stillbirth or delivery.

– In addition, the small print states that 700 of these 827 patients had received the vaccination in the last third of their pregnancy. Why does this number appear under miscarriages in the line „Spontaneous abortions: < 20 wk“, i.e. spontaneous miscarriages before the 20th week of pregnancy? These 700 cases in the last third of pregnancy (> 27th week of gestation) should not be mixed with those pregnancies that had ended before week 20.

– Colored in pink, 96 miscarriages before the 13th week out of 104 abortions all together.


However, I have a few other points of criticism:

– There is no control group, but early miscarriages are related to all terminated pregnancies in a non-representative collective. However, this is not a meaningful benchmark. It would have made much more sense to use an unvaccinated control group.

– Data were collected from women who had been vaccinated from 12-14-2020 through 02-28-2021 in this study and starting March 30, participants were contacted (p. 2275 right bottom paragraph). However, there was not much time since the study was already published on 04-21-2021. The follow-up was therefore extremely short and thus certainly not all miscarriages etc. could be recorded, as it is known that a pregnancy lasts 40 weeks.

By now, a follow-up study with the same patient population could have been conducted. In this case, there would have been more time for follow-up, to record the subsequent course of pregnancy, and to obtain more reliable data. In the conclusions of the abstract, the authors themselves state that more longitudinal follow-up studies are required. According to my search of PubMed and Google Scholar, there have not been any follow-up studies performed until today (Aug. 31, 2021). How come?

– It is incomprehensible to me that a study with such serious flaws was published in a renowned scientific journal!

– I am happy to engage in professional discussions and also revise my expressed evaluations, should I prove to be wrong.

09-14-2021 Important addition:

A colleague from Antwerp published a solid objection to the study in the NEJM, which in my opinion was very justified. As a result, the authors Shimabukuro et al. have retracted their assessment and write in the NEJM on 09-08-2021:

„We agree that the denominator used in that proportion — 827 completed pregnancies — is not an appropriate denominator for the calculation of a risk estimate or rate.“

Both can be read at:

In summary, this means: The authors cannot make any statement about the number of early miscarriages – in plain language:

An increased miscarriage rate in the first trimester of pregnancy cannot be excluded by this study!

09-27-2021 Second major addition:

The authors of the study criticized above are mostly members of the CDC (Centers for Disease Control and Prevention), which is roughly equivalent to the RKI (Robert Koch Institute) in Germany. Another group of authors also from the CDC (some individuals are involved in both studies: Ashley N. Smoots, Christine K. OlsonTitilope Oduyebo, Shin Y. Kim) published the following study on 09-08-2021:

Receipt of mRNA Covid-19 Vaccines and Risk of Spontaneous Abortion“

This study by Zauche et al. again uses a similar patient population and compares their pregnancy or early miscarriage rates to „historical cohorts“ and reportedly found no significant difference.


The study only captures pregnancies in the cycle before the onset of pregnancy and only again from the 6th week of pregnancy onwards. Anyone who is specialized in infertility knows that the most critical phase is precisely in early pregnancy until the 6th week of pregnancy. Exactly this sensitive phase is disregarded in this study. No IVF center would exclude this special period in the statistics for internal quality control after IVF.

So, in my medical opinion, the authors draw an absolutely wrong conclusion and deny an increased risk of miscarriage after / due to the Covid vaccinations. I seriously doubt this!

Another study, published 09-08-2021, also ruled out an increased risk from Covid vaccination for pregnancy:

Spontaneous Abortion Following COVID-19 Vaccination During Pregnancy“

This study by Kharabanda et al. only takes into account pregnant women who were vaccinated in the last cycle before the start of pregnancy or pregnancies that continued after the 6th to the 20th week of pregnancy as well. Again, the most critical phase, especially in early pregnancy, was omitted.

Thus, again, no statement can be made about the safety of the vaccination.


10-26-2021 Third addition:

I keep receiving emails wanting to correct the numbers on Shimabukuro et al. Here the listed numbers for clarification (p. 2276 bottom right):

827 terminated pregnancies, of which:

– 712 live births

– 104 miscarriages (of which 96 were before the 13th week of pregnancy)

– 1 stillbirth

– 10 induced abortions or ectopic pregnancies

Finally, two important comments:

– We know nothing at all about whether a Covid vaccination that took place longer than 6 weeks before conception could also have negative effects on the onset of pregnancy or the subsequent course of pregnancy. Zauche et al. and Kharabanda et al. did not investigate this either.

– Due to the abbreviated marketing authorisation of the gene-based vaccines, no animal studies were performed or published. Therefore, we know nothing about whether these vaccines could pose a risk to reproductive ability, child malformation rates, or increased cancer development. And what is more, nothing is known about long-term effects.

The fertility centers could check these open questions relatively easily with their statistics: every IVF center (IVF=in vitro fertilization) worldwide collects data on the pregnancy rates of their patients for quality control. And the vaccination status could very quickly provide information about the pregnancy outcomes of the vaccinated women compared to the unvaccinated control group.

I repeat my urgent request to all fertility centers in Germany and worldwide:

Please evaluate on the basis of your statistics of IVF-treatments the group of vaccinated women (never mind how long ago the final/second injection took place) against the control group of the unvaccinated women in accordance to:

how high are the pregnancy rates

how do the pregnancies continue

– are there differencies of birth outcomes

Please do not wait to see what the so-called „baby-take-home-rate“ (i.e. the babies born) after IVF-treatment will reveal, because by then it will be too late to prevent further possible harm.

This is not about politics, but this is about the well-being of our patients, their unborn children and families and their future.

Please help to disprove my fears!