The Institute of Obstetricians and Gynaecologists has defended advice it has given to the Department of Education that it is safe for unvaccinated school workers in the early stages of pregnancy to return to the classroom.
Institute chair Dr Cliona Murphy said the evidence shows that the risk from Covid-19 has been found in later pregnancy.
She said the evidence showed that people who were 10 or 14 weeks pregnant were no more at risk from the virus than the general population.
The country's three teacher unions earlier called again for teachers in this position to be allowed to work remotely.
Dr Murphy said she wanted to reassure teachers and others in this position that health experts here had not seen any adverse effects of Covid on the early part of pregnancy.
"We are conscious of tracking these admissions in hospitals, and we have not seen an increase in the preponderance of problems in early pregnancy," she said.
"What we have seen is towards the latter half of pregnancy. In actual fact, at 10 weeks, the risk seems to be similar to the ordinary person."
She said the same seemed the case for a pregnancy at 14 weeks gestation.
"We would be the first to say, if we thought there was an excess in miscarriage rates in the early stages. I would not hesitate," she said.
Meanwhile, Minister for Education Norma Foley has said that if a pregnant woman decides in consultation with her GP - or if her consultant recommends - that it is not appropriate to return to work, then there is a pregnancy-related leave available.
"That has always been in place, it remains in place," she said. "On foot of the recommendation of a GP or a consultant, women are entitled to avail of that."
Ms Foley said there are 183 days available under this pregnancy-related leave and it does not impact on any future sick-leave entitlements.
She reiterated that the Department of Education is following expert medical advice with regard to pregnant teachers returning to schools.
Earlier, the country's three teacher unions reiterated concerns at what they say is the State's failure to protect staff in early pregnancy from Covid-19.
Last term, teachers and other school staff who were pregnant were entitled to work from home. However, this provision has been removed for the new school year.
But people who are in the first 14 weeks of pregnancy are not currently eligible for vaccination.
In a joint statement the INTO, the ASTI, and the TUI say they are "alarmed that this small cohort of the school workforce is being sent back to school settings prematurely, prior to getting the opportunity to achieve significant vaccine protection".
The unions say they find it "incredible that Government expects vulnerable members in the early stages of their pregnancy to return to school buildings without vaccine protection".
They say that this is taking place amid increasing concern in respect of very high rates of community infection and growing unease about the transmissibility of the delta variant being central to regular public health messages from NPHET.
The unions have repeated a demand that these workers be allowed to continue to work remotely until they can receive a vaccine that will protect them.
They say that pregnant workers in the early stages of their pregnancy represent a small cohort of all pregnant staff and so any impact on the delivery of education would be very low.
"We condemn the failure of the Minister for Education and the Department of Education to provide alternative time-bound working arrangements for teachers who have been ineligible to receive vaccines. To cause a group of pregnant workers to endure weeks of anxiety and fear is unconscionable", the unions have said.
Speaking to RTÉ's News at One, general secretary of the ASTI Kieran Christie said that there are many teachers who are "pregnant and distressed" about returning to school without being fully-vaccinated.
He accused Minister Foley of being "disingenuous" in addressing their concerns.
Mr Christie said that Minister Foley "ducked the question" today by raising the solution of pregnancy-related sick leave, saying "we are talking about people who are not sick at all, they just want to work in a safe environment".
He said they are "more than willing to work remotely" and that in a few weeks time many who are worried will be fully-vaccinated and the problem "will become moot" but for now it is a problem.
The President of the INTO has said that with "a bit of ingenuity and a bit of flexibility", the Department of Education could resolve the issue.
Joe McKeown told RTÉ's Drivetime said pregnant teachers under 14 weeks who cannot get vaccinated should be allowed to work remotely.
"There will be loads of children next week who will not be able to go to school because they're close contacts or because they're unwell themselves and those teachers, working remotely from home, could assist those," he said.
Mr McKeown said there were many cases last year where teachers, who were working from home, were caring and providing an education for children who were learning remotely.
He said that system was in place and it will be in place for some high-risk category teachers this year.
"All the Minister has to do is to apply the same arrangement to a very small number of people, for a very short period of time in order to allay the anxieties and that's what she should do," he added.
Mr McKeown said the INTO was "very alarmed" and the teachers they represent are "very worried" by the Minister's comments that it is okay for pregnant, unvaccinated teachers to return to the classroom.
He said the INTO has had some "very heated" discussions with the Department of Education about the issue.
Earlier, Minister Foley was criticised by opposition TDs for saying that unvaccinated pregnant teachers could avail of sick leave.
Sinn Féin's education spokesman, Donnchadh Ó Laoghaire, said unvaccinated pregnant teachers should not have to avail of sick leave because they are not sick.
He added they should be allowed work remotely.
Labour's education spokesman Aodhán Ó Ríordáin said there were no real solutions being offered to pregnant staff.
Speaking on RTÉ's News at One programme, he said "it is pretty outrageous" for Minister Foley to encourage pregnant teachers to take sick leave when they are not sick.
He said "pregnancy isn't a sickness, it's not an illness and it's something that needs to have protections around, particularly in a pandemic when teachers are justifiably anxious going back into overcrowded classrooms without being fully vaccinated".
Mr Ó Ríordáin said he is quite sure that teacher unions, boards of management and patron bodies can find a solution to accommodate this group of teachers whether that means working from home or substitute arrangements, as it is only for a couple of months.
Additional reporting Aengus Cox