According to physicians in the UK, pregnant women should not stop taking iron tablets, despite research published in last week's JAMA, linking high haemoglobin and stillbirth.
Doctors in Sweden have found that a high level of haemoglobin in early pregnancy may increase the risk of stillbirth by up to four times, compared with women who have lower levels of iron in their blood.
But Dr Elizabeth Letsky, the UK's only consultant perinatal haemotologist says the levels of haemogolobin the researchers described were so high they would indicate that the mother had some underlying problem.
"Most women are fighing some degree of iron deficiency all their lives - the levels described in this study are almost unheard of," she said.
The research team from Stockholm's Karolinska Institutet reviewed more than 700 women who had a stillbirth between 1987 and 1996 and compared them with the same number of live births.
They found that women with haemoglobin levels of 146g/L or higher at their first antenatal appointment were nearly twice as likely as women with lower haemoglobin to have a stillbirth.
They also found that when they excluded stillbirths following pre-eclampsia or eclampsia, or where the baby was malformed, the link between haemoglobin levels and stillbirth was stronger still.
When they looked at stillbirths which had occurred after a premature labour the risk was almost three times greater for those with higher haemoglobin.
In cases where the stillborn baby was very small the risk was more than four times higher.
The doctors took into account other factors which may influence stillbirth such as smoking and maternal age and socio-economic group.
No need for panic
But Dr Letsky from the Institute of Obstetrics and Gynaecology at Queen Charlotte's Hospital in London says looking at haemoglobin levels gives no indication of the amount of iron stored in a woman's body.
"Very few women have haemoglobin levels of 146 and we have no idea what their iron stores are like - low iron stores don't just affect the woman, they can have a serious knock-on effect on the baby," she told BBC News Online.
Dr Rupert Fawdry, consultant obstetrician at Milton Keynes General Hospital, insisted women should not panic about the research findings.
"There are hundreds of things that modify stillbirth risk and there are some really significant ones like smoking.
While a link between high haemoglobin levels and stillbirth is feasible, the risk would be very small, he stressed.
The Swedish research, published in the Journal of the American Medical Association, also found that that a large decrease in haemoglobin in pregnancy "tended to be protective" and that anaemia did not seem to have any link with stillbirth.
Dr Fawdry added: "By the time someone is pregnant it is almost certainly too late to do anything about many of the risk factors. The logical thing is to get as healthy as you can before you get pregnant."