A Singapore couple who conceived their baby via in-vitro fertilisation are reeling from shock to discover that the child's DNA does not match the father's.

Their suspicions were first aroused when they noticed that their newborn baby's complexion was markedly different from theirs.

They then were told that the baby has type B blood, whereas their blood types are O and A.

The parents and baby then went through a DNA test, which showed that the baby has the mother's DNA make-up, but not the father's.

The couple now want answers from the Thomson Fertility Centre and have also sought legal advice.

Their lawyer, Mr S. Palaniappan, told The Straits Times yesterday that the couple are "dismayed and shocked".

"It became apparent to the couple that sperm which belonged to some unidentified person who had a B type blood group in place of the husband's sperm had been used to fertilise the egg, which was retrieved from the wife during the fertilisation procedure," he said.

The fertility centre said last night that it was unable to discuss or comment on any case.

"All our patients' information is treated with strict confidence. It is our policy to respect our patients' privacy and confidentiality," said Ms Patricia Lee, director of corporate development at Thomson Medical Centre Limited.

In a reply to The Straits Times last night, the Ministry of Health said it has been notified of the case and is investigating the matter.

Doctors say they have not heard of such a case happening in Singapore before.

The couple - a Singaporean Chinese woman and her Caucasian permanent resident husband who are both in their early 30s - have been married for about 10 years.

They had sought fertility treatment at the centre, which is part of the medical centre at Thomson Road, on the advice of their obstetrician.

The treatment they underwent involved retrieving eggs from the wife and fertilising them with sperm from the husband in a laboratory, before transferring the eggs back into her uterus.

The couple underwent this treatment in January this year. The wife gave birth on Oct 1, about 15 days before the due date, following an emergency caesarian operation.

They were told that the baby had the type B blood, which raised their concerns.

Four doctors interviewed yesterday said this is not possible for a child whose parents are blood types O and A.

The couple asked the medical staff about this, but did not get satisfactory answers initially, said Mr Palaniappan, who is from Straits Law Practice.

"They were then informed that there was a possibility that a mix-up could have taken place," he said.

The centre arranged for the couple and the baby to take two DNA tests last month - one from the Health Sciences Authority (HSA) here and, at the couple's request, another from a laboratory in Hong Kong, where results would be known earlier. The Hong Kong tests showed that the

DNA make-up of the child contained the DNA material of the mother, but not that of the father, thus hardening their belief that there was a mix-up during the IVF. The result of the HSA test is pending.

The couple sought further answers from the centre so that they can make an informed and not an emotional decision moving forward, said Mr Palaniappan.

The centre, through its lawyer Audrey Chiang from Rodyk and Davidson, acknowledged their letter on Oct 20, and said it would reply in due course.

The couple also wrote to the Ministry of Health requesting an inquiry into the matter.

A ministry official e-mailed an acknowledgement to the couple's lawyer on Oct 18, saying: "This is most unfortunate. We will do the necessary checks and do the needful."

Mr Palaniappan, speaking on the couple's behalf, said that while dismayed, "what is uppermost in their minds is the welfare of the child".

Among other things, the couple have instructed him to ask for copies of all records related to the IVF treatment, and records of all documents connected to those who underwent fertility treatment around that time, to enable them to ascertain the length and breadth of the mix-up.

They are prepared to get the records without the names and identities of other parties involved.

They also note the legal issues surrounding the registration of the child - the parents must fill out details in the baby's birth certificate soon.

The options being considered include fostering out the child pending a resolution of the case.

There are currently 10 centres offering fertility treatment in Singapore.

Thomson Fertility Centre, rated as one of the best private medical centres here for such treatments, is currently the subject of a takeover bid by billionaire investor Peter Lim.

Mr Lim, who already owns a 39.34 per cent stake, last week offered to buy up the rest of the shares at $1.75 per share, which would take its overall worth to $513 million.