An NHS hospital is proposing to make women show identification before providing them with maternity care in a bid to crack down on so-called health tourism in the NHS.
St George's University Hospitals NHS Foundation Trust in London has set out proposals which could mean women who attend hospital would need to show photo ID or proof of their right to remain - such as their asylum status or a visa - before receiving care.
Emergency patients would not be asked for their ID, the trust said.
The proposals, which have been set out in the Trust's October board papers, would need piloting before they are rolled out.
The papers state that the Home Office is "very keen" to support such a pilot scheme.
If women could not provide such identification they would be sent to the Trust's Overseas Patient Team "for specialist document screening, in liaison with the UKBA and the Home Office", the document adds.
The papers state that there is a rising number of overseas visitors who are accessing NHS care who are not entitled to treatment.
"The problem is escalating within obstetrics and we have just been made aware that individuals are currently offering paid assistance to women in Nigeria to have their babies for free on the NHS at St George's," an email in the board papers states.
The email, written by Jo Johnson, head of private and overseas patients for the trust, adds: "St George's is targeted as it does not currently have a robust process to check eligibility.
"We know from feedback from other non-eligible patients that St George's is viewed as an 'easy target'."
The email goes on to say that the local health economy is losing around £4.6m a year from patients who are accessing the system and are not entitled to.
It adds: "We have recently undertaken some work with the Cabinet Office and with UKBA. The Government are aware of the escalating problem faced by acute Trusts and are working on revised national guidance which is likely to advocate routine presentation of proof of identity and eligibility.
"Legislation is due to incorporate charging for A&E and ambulance services which will mean that Trusts will have to insist that this documentation is provided before care is given (unless it is an emergency/life or death situation)."
A St George's Hospital spokesman said: "Like many London Trusts, we treat a high number of patients from overseas who are not eligible for NHS treatment. All patients in need of emergency NHS care at St George's are treated and prioritised accordingly, regardless of their eligibility.
"Our priority at all times is to provide care and treatment to patients requiring our services. However, we also have a duty to ensure we use our resources wisely.
"The guidelines state that hospitals should endeavour to check patients for their eligibility when accessing non-emergency NHS treatment. We are not doing this effectively enough at present, and are looking at ways in which we can improve this.
"We will continue to treat patients presenting to St George's, whilst also looking at ways of tightening up our existing processes for ineligible patients accessing non-emergency treatment."
Commenting on the news, Rebecca Schiller, chief executive of the human rights in childbirth charity Birthrights, said: "It is unlawful to deny a labouring woman maternity care whatever her residential status.
"The current Department of Health overseas visitors guidance makes it clear that, while a woman who isn't ordinarily resident in the UK may be asked to pay for her maternity care, life-saving services should never be withheld if she cannot afford to pay or can't pay in advance."
Cathy Warwick, chief executive of the Royal College of Midwives, said: "This move by the trust is a concern. I am sure no trust would deny care to women in labour or who are pregnant and arrive at a hospital needing urgent care related to their pregnancy. To be clear, the law says, and government policy states, that trusts must offer care to women in labour, irrespective of their immigration status in the country.
"On the wider level, midwives also have more than enough to do without checking women's eligibility and determining their immigration status.
"They are not border guards; they are healthcare professionals there to deliver clinical care to all women. This is not their job and never should be, and we must assume that the trust will not require them to do this. Their job is to care for the women who walk through the doors of their maternity unit and it is the responsibility of trusts to care for and treat these women.
"Most importantly, this move could also be dangerous because it could deter women from seeking care in a timely fashion. This could potentially have a serious impact on the health of the mother and their baby and the outcome of the pregnancy.
"I would ask the trust to clarify their policy and to give assurances that all pregnant women who need care will receive it, no matter what their immigration status."