The government failed to anticipate the increased pressure immigrant birth rates would exert on maternity services, opposition politicians have claimed.
The number of births to foreign-born women has increased over the past decade, despite a falling birthrate among British women. This has led to a £200 million increase in spending on maternity services for immigrant women, independent analysis claims.
This trend has in turn increased pressure on maternity services, with midwives reportedly diverted to meet the needs of areas with a high immigrant population.
The Conservatives claim the government failed to anticipate the rising demand for maternity services created by foreign-born mothers.
Shadow health minister Stephen O'Brien told BBC Radio Five Live: "The real issue here is the government were rightly warned of this impending situation for years and now we find that they're guilty of no forward planning for the impact of immigration on public services - particularly the health service and particularly maternity services - and they were warned."
The Liberal Democrats have now called for a national review of maternity services, in order that ministers can "stop burying their heads in the sand".
Lib Dem health spokesman Norman Lamb accused the government of trying to have it both ways over immigration.
He said: "The government is happy to reap the economic benefits of migrant workers but is not willing to provide capacity to cope with the extra pressure that they bring to the NHS. They cannot have it both ways."
BBC analysis shows spending on maternity services has increased from £1 billion in 1997 to £1.6 billion now, including £350 million spent providing maternity care for foreign born women.
This is in the face of a 44,000 drop in the number of births to British women, compared to a 64,000 rise in babies born to immigrant mothers.
The Office for National Statistics shows one in five babies is now born to immigrant mothers, up from around one in eight a decade ago.
Last week's Healthcare Commission review of maternity services identified high immigrant populations as a potential factor behind the poorer performance of many London trusts.
The Liberal Democrats argue it is "essential" every expectant mother can access reliable and safe maternity services, while the Conservatives are calling for an increase in the number of midwives to meet targets for one-to-one care.
Following the Healthcare Commission's report, health secretary Alan Johnson announced additional funding for maternity services, rising to £122 million a year over three years.
Mr Johnson said the increase in funding would provide for more midwives as well as increase the choice in care available to women.