Clinical trial on pregnant women receiving COVID-19 vaccines reveals potential risks - DPF

Article Details

messenger Ask Dr. Patrick Flynn Right Arrow
article image

Clinical trial on pregnant women receiving COVID-19 vaccines reveals potential risks

Story at a glance

  • A pregnancy health organization, Pregistry, sponsors a clinical trial (C-VIPER) which will study the COVID-19 vaccines’ effects on pregnant women.
  • The trial commenced on January 15th, 2021 but will not end until December 31st, 2025.
  • The trial is meant to measure the risks in obstetric (pregnancy), neonatal (newborn), and infant outcomes.

C-VIPER Trials

On January 12th, 2021, it was revealed on that a study involving COVID-19 vaccines’ effects on pregnant women is underway.

The trial itself is titled as “COVID-19 Vaccines International Pregnancy Exposure Registry (C-VIPER)”.

According to the posting, the study began on January 15th, 2021 but will not be finished until it’s estimated end date of December 31st, 2025.

The purpose of this clinical trial is to observe the risk outcomes that pregnant women face if they receive a vaccine to prevent COVID-19. The listing’s rationale says, “COVID-19 vaccines will be used in pregnant populations. Scientific evidence regarding their safety for pregnant women and the developing fetus is lacking.”(1)

Current Status

The current listing reports they are not recruiting trial candidates yet, but their goal is to involve 5,000 participants in the study. The first two years of the study is dedicated to recruiting voluntary women, who will then be separated into two cohorts.

  • Cohort 1: pregnant women exposed from 30 days prior to the first day of the LMP (last menstrual period) to end of pregnancy to at least one dose of a COVID-19 vaccine. These participants are enrolled as part of the C-VIPER. (2)
  • Cohort 2: pregnant women unexposed to a COVID-19 vaccine before enrollment and had a negative screening test for the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) during pregnancy. (3)

The data collected from both cohorts will be compared to each other to determine the underlying risks associated with pregnant women receiving the COVID-19 vaccine.

c viper timeline

What are the risks?

During the third and fourth year of the trial follow-ups of the pregnancies and newborns will occur. Although data will be collected and reported on a continuous basis, these years will be crucial regarding thorough investigations.

The follow-ups are meant to measure the occurrence of pre-determined risks provided by researchers. Within the listing, there is a section dedicated to ‘Primary Outcome Measures’, where the potential risks are listed.

  • Potential Obstetric Outcomes: abortion, antenatal bleeding, dysfunctional labor, gestational diabetes, hypertensive disorders of pregnancy, intrauterine growth retardation, maternal death, non-reassuring fetal status, pathways to premature birth, postpartum hemorrhage, or COVID-19.
  • Potential Neonatal Outcomes: congenital anomalies, failure to thrive, low birth weight, neonatal death, neonatal encephalopathy, neonatal infections, preterm birth, respiratory distress in the newborn, small for gestational age, stillbirth, or COVID-19.

Who is Pregistry?

Pregistry, the conducting organization, describes themselves as “…a start-up company dedicated to improving maternal and fetal health by the collection, analysis, and sharing of accurate information in support of healthy pregnancies, healthy babies, and successful breastfeeding.”(4)

The Founder and CEO of the organization, Diego Wyszynski, will be leading the clinical trial as the Principal Investigator. 

Further Discussion

On Dr. Patrick’s show, A Different Perspective, you can find further discussion about the COVID-19 vaccine(s).

Here are some links to get you started:


(1-3). COVID-19 Vaccines International Pregnancy Exposure Registry (C-VIPER),, 2021.

4., 2021.