Do COVID vaccines cause miscarriage?

In a recirculated video, Dr. Kimberly Biss, an obstetrician, claims that after COVID-19 vaccines became available, the number of miscarriages in her practice doubled, which she attributes to the vaccine.

The claim that Pfizer’s COVID vaccine trials showed an 80% miscarriage rate likely comes from a misunderstanding of a study where not all pregnancies had complete follow-up data, resulting in misleading percentages. The actual miscarriage rate among pregnant women in the trials was consistent  (12.6%) with the normal rate seen in the general population, which is about 10-20%. Large studies and real-world data have shown that COVID vaccines do not increase the risk of miscarriage and are safe for pregnant women.

Of the 827 completed pregnancies, 104 ended in miscarriage. Those who claim the 80% stat are using semantics to make their argument, saying since miscarriage is defined as a loss of the fetus prior to 20 weeks, while a loss of a fetus after 20 weeks is considered a stillbirth, and therefore they remove anyone who received a vaccine in 3rd trimester, bringing the denominator down to 127 from 827, leaving us with the 80% figure.

Dr. Biss’ observation that miscarriages doubled in one doctor’s private practice does not prove that vaccines caused the increase. A single doctor’s experience does not replace large-scale scientific studies. And multiple studies worldwide have found no link between COVID vaccination and increased miscarriage rates.