COVID-19 Shows No Effect on Miscarriage Rates

Home » Female » COVID-19 Shows No Effect on Miscarriage Rates

COVID-19 shows no effect on miscarriage rates

Risk of Pregnancy Loss Prior to 20 weeks Gestation with COVID-19


Numerous studies to date have explored the potential effect of COVID-19 on birth outcomes.

However, studies of the well-known association of miscarriage with viral infections, specifically COVID-19 has been limited.

Previous studies were small in size, limited to inpatients, lacking long-term follow-up and specific to European or Asian populations.


Women in the US, aged 13 or greater, with symptoms or confirmed PCR testing for COVID-19, were enrolled in the PRIORITY study, investigating the effects of COVID-19 during pregnancy.

Women at 14 weeks or greater gestation, who did not undergo SARS-CoV-2 testing or have longitudinal follow-up were excluded from the final analysis.

Questionnaires were completed at enrollment, followed by weekly the next 4 weeks, and then less frequently beyond that throughout the pregnancy.

Medical records were then reviewed to validate any reported adverse outcomes by the women.

Early pregnancy loss was defined as pregnancy loss (miscarriage) before 20 weeks gestation.


Of the initial 1338 participants in the PRIORITY study, 109 women satisfied the inclusion exclusion criteria.

All 109 women were classified as outpatients, i.e. not requiring hospitalisation, showing symptoms of COVID-19, however 15 women tested negative, while 94 tested positive for COVID-19.

Demographic and clinical characteristics revealed the majority of women were white (66%), followed by Hispanic (33%). Average age was 31 and mean gestational age was 9 weeks and 5 days at the time of enrollment. 

Initial results showed that 6.4% (6/94) women positive for COVID-19 had early pregnancy loss compared with 6.7% (1/15) women negative for COVID-19.

In the positive group, 5 of 6 pregnancy losses occurred between weeks 7 to 12 with one other in week 15.

Further analysis of specifically COVID-19 positive women, who enrolled before 8 weeks gestation, showed a similar trend with early pregnancy loss in 5.9% (2/34).

Overall 84.4% (69/82) of women positive for COVID-19 had live births at term with the 15.6% (13/82) delivered before 37 weeks gestation, with the remaining 6 pregnancies still ongoing (>24 weeks gestation).

Researchers noted the 6% risk of pregnancy loss, in both COVID-19 positive and negative groups, was comparable to the standard 10% rate of miscarriage among first trimester pregnancies pre-pandemic.

In the COVID-19 positive group the upper bound confidence limit of the result, with this sample size, was only 13.4% which is slightly higher than the expected rate of miscarriage without any viral infections.


In this study, women who tested positive for COVID-19, during their first trimester of pregnancy, had a similar risk of miscarriage before 20 weeks gestation compared to women who tested negative (6.4% vs. 6.7%), inferring that coronavirus infection has no effect on the safety of an unborn baby.


  1. Small size control group


This research was supported by grants from the California Healthcare Foundation, the CDC Foundation, the Bill and Melinda Gates Foundation, the UCSF National Center of Excellence in Women’s Health, Yellow Chair Foundation and private donors.


The time between conception and birth.

A patient admitted into hospital for one or more nights of medical care.

Upper bound confidence limit
The probability that the true value is somewhere between this upper limit and the mean value.

Similar studies

la Cour Freiesleben N, et al. (2021). SARS-CoV-2 in first trimester pregnancy: a cohort study.

Cosma S, et al. (2020). Coronavirus disease 2019 and first-trimester spontaneous abortion: a case-control study of 225 pregnant patients.

Yan J, et al. (2020). Coronavirus disease 2019 in pregnant women: a report based on 116 cases.


Endometriosis and getting pregnant

Endometriosis is a common yet complex gynecological inflammatory disease characterized by the growth of endometrial-like tissue outside the…. Read more

Low Sperm Count Overview

Low sperm count, also known as oligospermia or oligozoospermia, happens when a man has 15 million or less sperm per millilitre (mL) of…. Read more

Questions or comments?