Pregnancy outcomes following COVID-19 infection and immunization

Researchers have evaluated the effects of COVID-19 immunization and infection on early pregnancy outcomes in a study that was published on the Research Square preprint server.

The risk of getting severe COVID-19 in pregnant women has been effectively reduced by vaccination against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, studies have shown that the pregnant population has a significant prevalence of vaccine reluctance. Pregnant women may be reluctant to receive the COVID-19 vaccine due to a number of circumstances, including the initial exclusion of pregnant women from vaccine trials, which resulted in inconsistent instructions for the immunization program's early stages due to a lack of safety-related evidence at that time.

To improve immunization programs, there is an urgent need for precise data on the safety of the COVID-19 vaccine during early pregnancy.

About the study

In the current investigation, researchers conducted a population-level matched cohort analysis to assess the relationship between COVID-19 immunization and ectopic pregnancy and miscarriage.

The Pregnancy in Scotland (COPS) cohort, which included all ongoing and completed pregnancies reported from January 1, 2015 onward in Scotland, provided data for the team's analysis. The data contained details about pregnancies, such as the expected dates of conception, and details about completed pregnancies, such as gestational age and pregnancy outcome. All pregnant women who were between the ages of 11 and 55 at conception had their data retrieved.

Using specific IDs, national information on COVID-19 infections and vaccinations was also added to the study group. Pregnancies with estimated conception dates up to 28 September 2021 and detected outcomes that occurred up to 31 January 2022 were included in the COPS database.

The team defined receiving any SARS-CoV-2 vaccination available in Scotland, such as BNT162b2, messenger ribonucleic acid (mRNA)-1273, and ChAdOx1-S at any dose, such as first, second, etc., as the primary exposure to the COVID-19 vaccine. From six weeks before conception to the end of the outcome-specific period, which was defined as the time frame between 19 weeks and six days of gestation (19 + 6 weeks) for miscarriage and a length of 2 + 6 weeks for ectopic pregnancy, eligible subjects received vaccinations.

All pregnancies were categorized as ongoing or over at 19 + 6 weeks in terms of study results. The outcomes of all completed pregnancies, such as miscarriage, ectopic pregnancy, or termination, were further grouped. The International Classification of Diseases (ICD)-10 or Read Coded Clinical Terms diagnostic codes recorded on the hospital discharge records were used to verify the outcomes of interest.

The team also contrasted the early pregnancy outcomes between women with and without a confirmed COVID-19 infection. From six weeks before conception until the conclusion of the outcome-specific period, the exposure of interest for the study was confirmed COVID-19 diagnostic through reverse transcription (RT), polymerase chain reaction (PCR), or lateral flow device (LFD) test.

Results

Only 526,608 of the 556,167 pregnancies reported by 361,606 women in the COPS study's database met the study's eligibility requirements. These included 126,956 pregnancy records from the current pandemic period and 399,652 pregnancy records from the pre-pandemic period. 18 780 pregnant women received the COVID-19 vaccine between six weeks before conception and 19 + 6 weeks of gestation, according to the research team.

The study's findings revealed that pregnant women received the BNT162b2 vaccine the most frequently, with one-fourth of the study population receiving two or more doses of the vaccine throughout the exposure period. Notably, compared to 9.9% and 10.0% of pregnancies from pre-pandemic and current controls, respectively, nearly 9% of the pregnancies from the vaccine group resulted in miscarriage by 19 + 6 weeks of gestation. Additionally, primary analyses utilizing pre-pandemic controls revealed no appreciable differences in the frequency of miscarriage among pregnant women who had received the vaccine.

Given that they came from the most underprivileged areas, ChAdOx1-S vaccination recipients had a higher likelihood of being labeled as clinically or very susceptible than mRNA-vaccinated pregnant women. In comparison to pre-pandemic or current controls, the subgroup analyses did not provide any evidence that women who received the mRNA vaccine were more likely to experience a miscarriage. The study did find that, compared to the pre-pandemic controls but not the modern controls, women who had received the ChAdOx1-S vaccine were more likely to miscarry.

Additionally, between six weeks before conception and 2 + 6 weeks of gestation, 10,570 pregnant women received vaccinations. Ectopic pregnancies represented nearly 1.2% of pregnancies in the immunized, 1.2% of pregnancies in the pre-pandemic controls, and 1.1% of pregnancies in the modern control groups by 19 + 6 weeks of gestation. The research team could find no proof that pregnant women who received vaccinations were more likely to have ectopic pregnancies. Furthermore, there was no proof that pregnant women who contracted SARS-CoV-2 had an increased risk of having an ectopic pregnancy or loss.

Overall, the study's findings did not support the hypothesis that COVID-19 infection or vaccination increased the incidence of ectopic pregnancy or miscarriage in pregnant women.