Experts say Pfizer Covid vaccine trials did not cause more miscarriages and there is no evidence of Covid-19 vaccine impact on fertility

No evidence Covid-19 vaccines affect fertility and pregnancies during Pfizer’s Covid vaccine trials

(Reuters) - Women who got pregnant during Pfizer’s Covid vaccine trials did not have an unusual rate of miscarriage, experts said as they responded to an online video.

In a Feb. 24 GB News interview that is circulating on social media, women’s health doctor Tina Peers says 58% of women who got pregnant during Pfizer’s vaccine trials miscarried (here, here and here). 

Pfizer did not address specific questions on the clinical trial miscarriage rate but pointed Reuters to a “summary of product characteristics” approved by the European Medicines Agency (EMA), which says no increased risk for miscarriage has been seen for the vaccine (here).

The 58% figure was wrong, Dr Victoria Male, an immunology and pregnancy specialist and senior lecturer at Imperial College London, told Reuters.

Peers based her claim on a periodic safety update which appeared to be made by Pfizer to the EMA (here, table 38), which reported 149 pregnancies occurring in the trials in total, with 21 ending in miscarriage.

Pfizer did not comment on the authenticity of the document.

This is a miscarriage rate of 14%, which is within the “normal” or expected rate of miscarriage per pregnancy, Male said. The “best estimate” available in medical literature on standard miscarriage rates, she added, is between 12.5% and 18.7% (here).

Peers later acknowledged the 58% figure was incorrect in an email to Reuters and a post on Twitter (here).

She said her original claim that 25 became pregnant and 15 miscarried came from one subset of pregnancies in the EMA safety update and acknowledged the miscarriage rate for total pregnancies was 14%.

INITIAL CAUTION

Britain’s Medicines and Healthcare products Regulatory Agency (MHRA) did not initially clear the Covid vaccine for pregnant and breastfeeding women due to an absence of data at the time, according to a Dec. 2020 public assessment report of Pfizer-BioNTech’s Covid-19 vaccine cited in the GB News segment (here).

But the UK’s vaccine advisory group later recommended the vaccine be offered to those who are pregnant based on real-world U.S. data suggesting its safety (here).

Extensive observational data now available suggests no increase in adverse pregnancy outcomes in the second or third trimester of pregnancy and no increased risk for miscarriage, according to MHRA guidance updated in Jan. 2023, which flagged limited data on first trimester outcomes (here).

Covid-19 vaccines are safe during pregnancy and reduce the risk of pregnancy complications from the virus itself, according to experts (here).

NO EVIDENCE OF IMPACT ON FERTILITY

During the Feb. 24 interview on GB News, Peers also said that it is “most peculiar” that fertility studies were not carried out on humans or animals before the trials. She did not spell out what she saw as the implications of this in the clip.

The MHRA acknowledged that no fertility assessments would have been carried out on people before they took part in the trials, but they said an assessment of fertility would not generally be a requirement for participants before or after a clinical trial.

They also said there is no evidence of impact from Covid-19 vaccines on fertility.

“Based on our current rigorous safety monitoring, women can be reassured that the current evidence does not … suggest that Covid-19 vaccines will affect fertility,” an MHRA spokesperson for told Reuters.

Pfizer started a global trial of pregnant women in February 2021. Before this, it conducted a reproductive toxicity study in animals which it said showed “no evidence of fertility or reproductive toxicity” (here). The study of rats was published online in Aug. 2021, detailing no effect on fertility or pregnancy outcomes (here).

GB News did not respond to a Reuters request for comment.

VERDICT

False. There is no evidence that Covid-19 vaccines affect fertility and pregnancies during Pfizer’s Covid vaccine trials did not have an unusual rate of miscarriage.