Miscarriages and COVID Vaccines
So COVID Vaccines and Miscarriages are being discussed again. Fortunately we are making progress and nobody is claiming 40-80% miscarriage rates.
Lets define miscarriage rate
Spontaneous abortion or miscarriage is defined as the loss of pregnancy less than 20 weeks gestation. The American College of Obstetricians and Gynecologists (ACOG) estimates it is the most common form of pregnancy loss. It is estimated that as many as 26% of all pregnancies end in miscarriage and up to 10% of clinically recognized pregnancies. Moreover, 80% of early pregnancy loss occurs in the first trimester. The risk of miscarriage decreases after 12 weeks gestation.
https://pubmed.ncbi.nlm.nih.gov/30422585/
Miscarriage Rate for our purposes = miscarriages in all clinically recognized pregnancies at <20 weeks gestation divided by the sum of all clinically recognized pregnancies
I’ll start with Arkmedic as he links to and discusses Igors post that mentions CDC V-Safe Pregnancy data
There are 2 slides in particular
817 miscarriages out of 20,985 pregnancies (live birth and miscarriage only), so 3.9% miscarriage rate. Sounds low because they included pregnancies that received their first injection at or greater than 20 weeks. By definition, miscarriages occur before 20 weeks.
Now this slide
Pregnant women with a clinical dx of pregnancy at 6 weeks who had an injection at anytime before 20 weeks are whom we are interested, even those who got injected before they knew they were pregnant or before they conceived.
This includes
Pre-Conceptional-2.245
First Trimester -6,352
Second Trimester (<20 wks)
Second Trimester means 13-24 weeks. So lets estimate that 7/12 of the Second Trimester injections were before 20 weeks
That gives us 5.293
Pre-Conceptional-2.245
First Trimester -6,352
Second Trimester (<20 wks)-5,293
So the denominator we want is 13,890
Lets calculate the miscarriage rate again.
817/13,890. Thats 5.9%
Here is the study Arkmedic sites as the Gold Standard
From January 2015-December 2017, 2,446 women met the inclusion criteria for the study and 132 (5.4%) had a pregnancy loss <20 weeks. On regression analysis, the independent risk factors for pregnancy loss were earlier gestational age (aOR 0.72, 95% CI 0.65–0.80) and increasing number of prior miscarriages (aOR 1.56, 95% CI 1.32–1.83). Using these risk factors, we calculated the stratified risk of pregnancy loss, which ranged from 0.8% in women at 13 weeks of gestation with no prior miscarriages to 33.7% in women at six weeks of gestation with three or more prior miscarriages.
The above paper has 137 reviews and 0 citations, and as it is behind a payroll we cant determine the age or race of the cohort. It’s fairly small sample so if the subjects are younger or lower risk than the population the lower number might be explained
Even so, 5.4% vs 5.9% is pretty close
V-safe Registry-October Letter
In the sensitivity analysis, under the extreme assumption that all 65 participants with most recent contact during the first trimester had a spontaneous abortion, the cumulative risk of spontaneous abortion from 6 to less than 20 weeks of gestation was 18.8% (95% CI, 16.6 to 20.9); after age standardization, the cumulative risk was 18.5% (95% CI, 16.1 to 20.8).
1/
2/
https://www.nejm.org/doi/full/10.1056/NEJMc2113891
The Letter is arguing 11-22% is acceptable. Not buying that. And how did we go from 14-18% to 5.9% in the most recent data? Well, we didn’t. Read on.
Appendix to Letter
There are few high-quality epidemiologic studies of SAB risk from 6-<20 weeks, with virtually all estimates falling within the range of 11-22%.
Given the lack of control group for this report, we used references from literature to evaluate whether the risk of SAB following COVID-19 vaccination preconception or during pregnancy was higher than what would be expected in the general population. Our registry had a higher percentage of White women than some other cohorts, 8,9 but registry participants had other characteristics predisposing them to higher risk of SAB, including older age
We used the 11.1% cumulative risk estimate for comparison given that other studies as well as our report examined cumulative risk of SAB from 6-<20 weeks’ gestation
[this is interesting, the authors of the Letter which used 11-22% as the Compator are not all of the Authors in the Appendix. The latter seem to feel 11.1% should be the comparator ]
The study population for Magnus et al. 2019 consisted of all registered pregnancies between 2009-2013 from three national health registries in Norway (n=421,201).6 A mean maternal age was not reported, but 20.9% were aged over 35 years.6 Previous SAB was reported by 18.8% of study participants.6 In this paper, SAB risk ranged from 9.8% (participants aged 25-29 years) to 53.6% (participants aged 45+ years), for an overall risk of 12.8%.
Age Stratified Data
165 SAB /2426= 6.8%
[This is the number to be compared with the more recent data from CDC which we estimate to be 5.9%. Assuming 5.4% as the Comparator that is proposed by Arkmedic we have from CDC V-Safe Pregnancy Register Data
October 2021- 6.8% (+26%)
Current 2022 -5.9% (+9%)
Thats quite a disparity (October 2021 from 5.4% comparator and October 2021 Data to Current CDC Data). Maybe the vaccines have been cleaned up a bit or CDC has gotten better at cleaning up the data. By now nobody can trust anything from CDC
Also, it appears Cumulative Risk is a higher number than the raw calculation of Miscarriage %. The accepted Cumulative Risk seems to be 11% per the Appendix yet the Letter wants to sell us on 11-22% because their data shows a Cumulative Risk of 14% which is 27% higher than 11%]
https://www.nejm.org/doi/suppl/10.1056/NEJMc2113891/suppl_file/nejmc2113891_appendix.pdf
What I really want to know though, is the impact on live births, and down the road, how those live births do in terms of health and development
Unfortunately US birth data unlike other countries is scarce. Fortunately we have California. I did this analysis in September so maybe the numbers have been update
CA Provisional Births
https://data.chhs.ca.gov/dataset/test-cdph-statewide-live-birth-profiles/resource/cad870a3-1576-4fb4-b21c-c75ceed5d60d
2021. 2022
Jan. 31986. 34519 (+7.9%)
Feb. 30097. 31972. (+6.2%)
Mar. 34649. 35419. (-2.2%)
Apr. 33488. 32557 (-2.8%)
May. 34373. 34007 (-1.1%)
June. 34950. 34086. (-2.5%)
July. 36481. 35665. (-2.3%)
I don’t see much here. Remember, small yoy declines are normal. The bump earlier in the year in 2022 are due to 2021 lockdown lows as a result of 2020 Lockdowns
Of course, we don’t know how many women were foolish enough to get the jab in their first trimester. I bet most were smart enough to delay until later in their pregnancy if at all.