Did Fauci lie about miscarriages after COVID vaccines?

Anti-vaxxers like James Thorp are saying that text messages written by Dr. Anthony Fauci during the pandemic prove that COVID vaccines caused miscarriages over 80% of the time.

• The study these claims are based on found a 12.6% miscarriage rate, not 82%.
• The 82% figure came from removing 700 live births from the calculation.
• That 82% does not represent the miscarriage risk after first-trimester vaccination.

James Thorp has previously made claims about COVID vaccines that have been challenged by scientists and fact-checkers. In this case, he claims that COVID vaccination during the first trimester of pregnancy led to an 82% miscarriage rate. A miscarriage is the loss of a pregnancy before the baby can survive outside the womb.

Thorp points to a study that reported a miscarriage rate of 12.6%. He argues that the study’s own data show a much higher rate of 82%. However, that number comes from using the study’s data in a way that does not make sense.

The researchers had complete information about 827 pregnancies that had ended by the time they analyzed the data. Of those pregnancies, 712 ended in a live birth and 104 ended in miscarriage. The study calculated the miscarriage rate by comparing the number of miscarriages with the total number of completed pregnancies in this group. That calculation was 104 miscarriages out of 827 completed pregnancies, or about 12.6%.

Thorp calculated the rate differently. He removed 700 live births because those people had received the vaccine during the third trimester, or the last three months of pregnancy. He then divided the 104 miscarriages by the 127 remaining pregnancies. That calculation gives a rate of about 82%.

The problem is that the 104 miscarriages and the 127 pregnancies are not matching groups. In a fraction, the bottom number is called the denominator. It tells us the whole group we are comparing. If some pregnancy outcomes are removed from the denominator but the miscarriages are left in the calculation, the percentage can become much larger and may give a misleading picture.

Because the researchers were looking at pregnancy outcomes, the miscarriage rate needs to be calculated using groups that can be fairly compared. The 82% figure does not mean that 82% of people vaccinated during the first trimester had a miscarriage. It only shows that 104 miscarriages make up about 82% of the 127 pregnancy outcomes left after 700 live births were removed from the calculation.