Pregnant women would be wise not to lose sight of their handbag or mobile phone, research suggests.
Among the many odd effects that pregnancy can have, one of them appears to be increasing the risk of losing things.
Scientists found women in the later stages of pregnancy tend to suffer a loss of spatial memory -- the memory of locations and positions of objects.
The problem was apparent in the last six months of pregnancy and lasted at least three months after a woman had given birth.
Experts believe it can be traced to the effect of pregnancy hormones on the brain.
Study leader Diane Farrar, a midwife, said: "Forgetfulness and slips of attention are phenomena commonly reported by pregnant women, but scientists have yet to identify a specific mechanism by which this memory impairment might occur.
"Indeed, some question whether the reported memory loss exists at all.
"Altered hormone levels during pregnancy may affect brain regions involved in memory processing."
The researchers compared 23 expectant mothers and 24 non-pregnant women who were given tests of different kinds of memory.
Mood, anxiety and attention levels were also measured, as well as concentrations of hormones in the blood.
Overall, pregnant women performed significantly less well than non-pregnant women in the spatial memory test during the second and third trimesters. Spatial memory relates to position and location.
It is used when people try to remember where they have left belongings, or navigate a familiar route by recognising landmarks.
The mood tests revealed that pregnancy led to an increased risk of anxiety and depression, but this trend faded away after birth.
"Mood and level of anxiety improved following pregnancy, suggesting hormonal influences may be responsible," said Ms Farrar.
"More research is now needed to identify the neurological effects of pregnancy to help guide future research."
The findings were presented today at the Society of Endocrinology BES meeting taking place in Manchester.