Pregnancy outcomes after COVID-19 vaccination and infection

In a recent study posted to the Research Square* preprint server, researchers assessed early pregnancy outcomes after coronavirus disease 2019 (COVID-19) vaccination and infection.

Study: Early pregnancy outcomes following COVID-19 vaccination and SARS-CoV-2 infection: a national population-based matched cohort study. Image Credit: M M Vieira/Shutterstock

Vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has proven effective against the risk of contracting severe COVID-19 in pregnant women. However, studies have reported high levels of vaccine hesitancy among the pregnant population. Several factors potentially enforce COVID-19 vaccine hesitancy among pregnant women, such as the exclusion of pregnant women from vaccine trials in the initial phases, leading to inconsistent guidance in the early phases of the vaccination program due to a lack of safety-related data during those times.

There is an urgent requirement to obtain concrete evidence concerning COVID-19 vaccine safety in early pregnancy to develop better vaccination policies.

About the study

In the present study, researchers performed a population-level matched cohort study that evaluated the association of miscarriage and ectopic pregnancy with COVID-19 vaccination.

The team obtained data from the population-based and dynamic report on COVID-19 in the Pregnancy in Scotland (COPS) cohort, which comprised all ongoing and completed pregnancies recorded from 1 January 2015 onwards in Scotland. The data included information related to pregnancies, such as the estimated conception dates, while the completed pregnancies included information related to gestational age and pregnancy outcome. This data was extracted for all pregnant women aged between 11 and 55 at conception.

National data related to COVID-19 infections and vaccination were also incorporated using unique identifiers into the study group. The COPS database included pregnancies having an estimated conception date up till 28 September 2021 and detected outcomes that occurred up to 31 January 2022.

The team considered the primary exposure to the COVID-19 vaccine as the receipt of any SARS-CoV-2 vaccine available in Scotland, including BNT162b2, messenger ribonucleic acid (mRNA)-1273, and ChAdOx1-S at any dose such as first, second, et cetera. Eligible participants were vaccinated from six weeks before conception until the end of the outcome-specific period, defined as the period between 19 weeks and six days of gestation (19 + 6 weeks) for miscarriage and a duration of 2 + 6 weeks for ectopic pregnancy.

Concerning study outcomes, all pregnancies were classified as ongoing or completed at 19 + 6 weeks. All completed pregnancies were further groups as per outcomes such as either miscarriage, ectopic pregnancy, or termination. The outcomes of interest were verified according to the International Classification of Diseases (ICD)-10 or Read Coded Clinical Terms diagnostic codes reported on the hospital discharge records.

Furthermore, the team compared early pregnancy outcomes among women who did and did not have a confirmed COVID-19 infection. The exposure of interest for the study was confirmed COVID-19 diagnosis from six weeks before conception until the end of the outcome-specific period tested via reverse transcription (RT) polymerase chain reaction (PCR) test or a lateral flow device (LFD) test.                     


The COPS study database comprised data related to 556,167 pregnancies reported by 361,606 women among which only 526,608 pregnancies were eligible for the study. These included 399,652 pregnancies recorded in the pre-pandemic period while 126,956 pregnancies were recorded in the contemporary pandemic period. The team noted that 18,780 pregnant women were immunized with the COVID-19 vaccine between six weeks before conception and 19 + 6 weeks of gestation.

The study results showed that BNT162b2 vaccine was most frequently received by the pregnant women while one-fourth of the study cohort were vaccinated with two or more doses during the exposure period. Notably, by 19 + 6 weeks of gestation, almost 9% of the pregnancies from the vaccinated group ended in miscarriage as compared to 9.9% and 10.0% of pre-pandemic and contemporary controls. Moreover, primary analyses performed using pre-pandemic controls showed no considerable difference in the occurrence of miscarriage among vaccinated pregnant women.

Compared to mRNA-vaccinated pregnant women, women who received the ChAdOx1-S vaccine had a higher chance of being categorized as either clinically or extremely vulnerable since they belonged to the most deprived regions. The subgroup analyses displayed no evidence that mRNA-vaccinated women were more likely to suffer from a miscarriage as compared to the pre-pandemic or contemporary controls. The team did observe that women vaccinated with ChAdOx1-S were more likely to experience a miscarriage in comparison to the pre-pandemic controls but not the contemporary controls.

Furthermore, 10,570 pregnant women were vaccinated between six weeks before conception and 2 + 6 weeks of gestation. By 19 + 6 weeks of gestation, ectopic pregnancies accounted for almost 1.2% of the pregnancies in the vaccinated, 1.2% of pregnancies in the pre-pandemic controls, and 1.1% of pregnancies in the contemporary control groups. The team found no evidence favoring that women vaccinated during pregnancy had a higher chance of experiencing an ectopic pregnancy. Additionally, no evidence was found supporting that women infected with SARS-CoV-2 during pregnancy had a higher chance of suffering from ectopic pregnancy or miscarriage.

Overall, the study findings showed no evidence of a higher risk of ectopic pregnancy or miscarriage among pregnant women after COVID-19 vaccination or infection.

*Important notice

Research Square publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Journal reference:
  • Sarah Stock, Clara Calvert, Jade Carruthers et al. (2022). Early pregnancy outcomes following COVID-19 vaccination and SARS-CoV-2 infection: a national population-based matched cohort study, 19 August 2022. Research Squaredoi:

Posted in: Medical Science News | Medical Research News | Disease/Infection News

Tags: Conception, Coronavirus, Coronavirus Disease COVID-19, covid-19, Diagnostic, Ectopic Pregnancy, Hospital, International Classification of Diseases, Miscarriage, Pandemic, Polymerase, Polymerase Chain Reaction, Pregnancy, Research, Respiratory, Ribonucleic Acid, SARS, SARS-CoV-2, Severe Acute Respiratory, Severe Acute Respiratory Syndrome, Syndrome, Transcription, Vaccine

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Written by

Bhavana Kunkalikar

Bhavana Kunkalikar is a medical writer based in Goa, India. Her academic background is in Pharmaceutical sciences and she holds a Bachelor's degree in Pharmacy. Her educational background allowed her to foster an interest in anatomical and physiological sciences. Her college project work based on ‘The manifestations and causes of sickle cell anemia’ formed the stepping stone to a life-long fascination with human pathophysiology.

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