Delta-Phase CoViD-19 Quadrupled Stillbirth Rate. So, what’s the “pro” choice on vaccines?

A massive CDC study of 1.2 million births during the CoViD-19 pandemic found that the rate of stillbirths more than quadrupled for pregnant women who were infected with the SARS-CoV2 coronavirus during the period when the delta variant became predominant.  Since CoViD-19 vaccines reduce infection rates, vaccine “choice” suddenly has implications for perinatal survival rate.

Stillbirth is the loss of a baby after the 20th week of pregnancy.  It’s normally rare in the U.S — affecting just 1 in 160 births* but, in a country that annually sees almost 4 million births, that sort of phenomenon can have a big cumulative impact: About 24,000 babies are stillborn each year in the U.S.  In a new CDC study pregnant women who tested positive for the SARS-CoV2 virus early in the pandemic experienced a slight increase in the rate of stillbirth (rising from 1 to ~1.6 out of 160 births), but that rate spiked even higher when the biologically novel delta variant displaced earlier variants of the virus. In the study period from July to September, 2021, when delta took over, pregnant women in the study who tested positive for SARS-CoV2 experienced an extraordinary rate of more than 4.3 stillbirths per 160 births. For the infected population that is more than 4X the typical rate of stillbirths in the US.

Given the nature of viral transmission, most of the people who infected those pregnant women with the SARS-CoV2 virus may never know they acted as viral vectors in that manner, however some relevant facts are available to anyone who is looking to inform their vaccination choices in the middle of the still-ongoing pandemic:

  • Vaccinated people appear to be 3-5X less likely to host or carry a SARS-CoV2 infection (see CoViD-19 Good News Trifecta).
  • A vaccinated person who does get infected is likely to clear their own infection faster1, 2 and get less sick than an unvaccinated person.3, 4
  • Vaccinated people, in the aggregate, reduce the burden on local hospitals, which makes healthcare more available in high-demand periods, and less expensive for everyone.5, 6 
  • Counties with higher vaccination rates have lower incidence of infection, and therefore ostensibly less circulating virus.7
  • The CDC recommends CoViD-19 vaccines for most pregnant women8 (but of course every person should consult with their healthcare practitioner to make individual medical decisions).
Adapted and extended from NY Times article of November, 2020. Baseline shows small deviations from average deaths per week from all causes in the US (2015-2021). A spike can be seen in 2017-18 during an extraordinary flu outbreak, but the overall death rate (deaths from all causes) explodes in 2020-21 with the arrival of the SARS-CoV2 virus and CoViD-19.

Although the SARS-CoV2 virus does not make everyone sick, it depends on people to spread to those who do get sick, and its hidden health effects on communities continue to reveal themselves through ongoing research.  In addition to increasing the rate of stillborn infant mortality, and contributing to the >840,000 American deaths that have been officially attributed to CoViD-19, people are increasingly noticing that the arrival of the SARS-CoV2 virus ushered in a massive spike in the overall US rate of death from all causes (see graph at right/above). The New York Times reported this in a particularly clear format in March.  We verified their report and extended their graph beyond the date of their publication (blue section in the graph at right).

Questions about personal “choice” are not new in the arenas of pregnancy or vaccination, but never have those questions intersected so directly. If the SARS-CoV2 virus contributes to increased prenatal mortality, and CoViD vaccines reduce the number of CoViD cases, then studies like this introduce new evidence that vaccinating against CoViD-19 could indirectly reduce the number of stillborn infants.

At the time of this writing 522 million doses of CoViD vaccine have been administered in the US — providing 75% of of Americans with at least a partial vaccination.  More than 62% of Americans are fully vaccinated. Those massive numbers of vaccination have provided extensive opportunity to document the safety of the vaccines.

*Note that we have normalized ratios in this piece to the 1/160-births ratio — to simplify comparisons of stillbirth rates. See also CoViD Good News Trifecta: New Studies Find That CoViD Vaccines Reduce Cases, Hospitalizations, and Deaths.

Matt Rain is a molecular geneticist who works on novel data analysis technologies to unstick persistent bottlenecks in biomedical research. He recently did a short guest spot on the This Week in Virology podcast (on YouTube here), which offers a little more background.