Pregnant women are being warned that headaches could be masking serious underlying health conditions.

Kirsty Revell, a specialist registrar in obstetrics and gynaecology at the Princess Anne Hospital in Southampton, Hampshire, said 90% of headaches experienced by mothers-to-be were a result of migraine or tension and usually improved or stopped during the last six months of pregnancy. But a small percentage were caused by potentially life-threatening neurological conditions.

Ms Revell said: "Some headache types can be more dangerous and an indication that something is seriously wrong."