The proportion of babies born to mothers with confirmed COVID-19, and who subsequently tested positive for the SARS-CoV-2 virus (which causes COVID-19) was 2 per cent in the UK study, and 1.8 per cent in the US study.
The majority of women in the study had no pre-existing conditions such as diabetes or a respiratory condition such as asthma.
In the UK study eight of the women died, while four women died in the US study.
The study team say that although these death rates are higher than expected for women giving birth, they are similar to the expected death rates seen among adults with a confirmed COVID-19 infection. This suggests that women in pregnancy are not at a higher risk of death from COVID-19 than non-pregnant women.