The Royal College of Obstetricians and Gynaecologists (RCOG) and the Royal College of Midwives (RCM) said they were concerned over a hesitancy among pregnant women to get vaccinated amid infections rising across England.
The RCOG added that around 58% of pregnant women are refusing the vaccine, according to its internal data.
Dr Mary Ross-Davie, director for professional midwifery at the RCM, said: “The delay to getting official information and advice out to pregnant women, as well as to healthcare staff delivering the vaccine, has undoubtedly caused further confusion among pregnant women.
“It’s something that both the RCM and RCOG had been lobbying heavily for since the vaccination programme began.
“But we can’t turn back the clock, we can only look to providing the right support and guidance to women who are pregnant now.
“We would of course have liked to have seen a widespread Government public information campaign about the vaccine in pregnancy to address the misinformation that is out there.
“We urge women to speak to their midwife or doctor to get clear and factual information, or to go to the official government website.”
Data from the UK Obstetric Surveillance System (UKOSS) has shown that one in 10 pregnant women admitted to hospital with symptoms of Covid-19 need intensive care.
It is also twice as likely that pregnant women with Covid symptoms will give birth to premature babies.
Recent studies have also found that pregnant women with Covid at the time of birth were more likely to develop pre-eclampsia and need an emergency caesarean, and had higher rates of stillbirth.
However, the actual increases recorded in those areas remain low, the RCM and RCOG said.
Both maternity colleges said they have regularly advised the Joint Committee on Vaccination and Immunisation (JCVI), to make it aware of the evidence relating to increased risks of severe Covid-19 in pregnancy, over the past six months.
Dr Edward Morris, RCOG president, said: “We are concerned that increasing rates of Covid-19 infection will adversely impact pregnant women, due in part to our data showing 58% of (pregnant) women have declined the Covid-19 vaccine.
“We know that those who are pregnant (and have) Covid are at an increased risk of becoming severely ill, particularly in their third trimester, and the vaccine is the safest and most effective way of protecting women and their babies.
“From the numbers of pregnant women admitted into intensive care with Covid-19 over the past few weeks, it is clear that the risk is reduced for those who have received the vaccine, particularly if they have had two vaccinations.”
Gill Walton, chief executive of the RCM, said: “In February and May 2021, the RCOG carried out a survey of pregnant women around vaccine uptake.
“Of those not accepting, the main reason cited was they were waiting for more evidence to reassure them that it is safe for their baby.
“Yesterday, Public Health Scotland reported that 4,000 pregnant women have received a vaccine with no adverse effects recorded.”
Both colleges have also advised unvaccinated or partially vaccinated pregnant women to continue practising social distancing, and for pregnant employees to continue following the occupational health guidance from the Government.
A Department of Health and Social Care spokesperson said: “We encourage pregnant women to discuss the risks and benefits of vaccination with their midwife, obstetrician or GP and consider precautions they can continue to take or limiting close contact with people until 21 days after their second dose of a Covid-19 vaccine. “