A rise in stillbirths between April and June, at the peak of the coronavirus pandemic, has prompted a national review by a patient safety body in England.
During that period, there were 40 stillbirths after labour began, compared with 24 in the same period last year.
The Healthcare Safety Investigation Branch will release its report in 2021.
Pregnancy and childbirth experts say women may have delayed seeking care.
The Royal College of Obstetricians and Gynaecologists said the figures were “concerning”.
But it was waiting for more data from after the pandemic to compare numbers of stillbirths over a longer timeframe.
The Office for National Statistics is due to release more recent figures soon.
RCOG president Dr Edward Morris said antenatal care was “essential” and encouraged all women to attend appointments.
In a survey of nearly half of maternity units, 86% said fewer heavily pregnant women than normal had come forward with emergency issues in April, during lockdown.
“This may have been due to confusion around whether these appointments are essential, fear of attending a hospital or not wanting to burden the NHS,” Dr Morris said.
“We have consistently advised women who have concerns or worries about their or their baby’s health – including the baby’s movements – should seek medical advice from their midwife or hospital immediately.”
The RCOG is also carrying out a national investigation of the “potential indirect effects of Covid-19 on pregnancy outcomes” before and after childbirth.
And, in the meantime, it is urging hospitals to avoid redeploying maternity staff during the second wave of the pandemic.