Intended for healthcare professionals

Rapid response to:


Facilitating participation in clinical trials during pregnancy

BMJ 2023; 380 doi: (Published 06 February 2023) Cite this as: BMJ 2023;380:e071278

Rapid Response:

Outstanding Results from Covid-19 Vaccine Trial in Pregnancy

Dear Editor

Nicola Vousden and colleagues point out that the covid-19 pandemic did not buck the trend to exclude pregnant women from nearly all vaccine and therapeutic trials.

In addition to the Recovery trial that they describe, there has been a prospective randomised clinical trial of the safety of covid-19 vaccination during pregnancy. Results of the trial NCT04754594 (1) which ended in July 2022 have yet to be announced. This was a Phase 2/3 study of BNT162b2 vs placebo in 349 healthy pregnant women.

When available, the data from this trial will enable women to make more informed decisions about the risk-benefit ratio of vaccination during their pregnancy.

Fever is a recognised reaction to vaccines, occurring, in the case of BNT162b2, in 11 – 16% of recipients (2). Typical advice (3) is to self-medicate with paracetamol (acetaminophen).

However, both fever (4) and ingestion of paracetamol (5) during pregnancy have independently been linked with the subsequent detection of an increase in incidence of neurodevelopmental disorders in the child.

Long term follow-up of the children born to vaccinated mothers will be needed and it is to be hoped that the UK Teratology Information Service will keep this under review.


2) Polack, P., Thomas, S., N. Kitchin, N. et al. Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine N Engl J Med, 383 (2020), pp. 2603-2615, 10.1056/NEJMoa2034577


4) Hornig, M., Bresnahan, M., Che, X. et al. Prenatal fever and autism risk. Mol Psychiatry 23, 759–766 (2018).

5) Alemany, S., Avella-García, C., Liew, Z. et al. Prenatal and postnatal exposure to acetaminophen in relation to autism spectrum and attention-deficit and hyperactivity symptoms in childhood: Meta-analysis in six European population-based cohorts. Eur J Epidemiol 36, 993–1004 (2021).

Competing interests: No competing interests

07 February 2023
Peter Selley
Retired GP
Crediton, Devon