Pregnant women who suffer lapses(忘却) in memory or concentration may no longer be able to blame it on "the bump". The idea that bearing children affects one’s brain power---the "baby brain"--is a myth, researchers say. Their study found no difference in how pregnant women or new mothers scored on tests of thinking speed and memory compared with those who were childless. Writing in the British Journal of Psychiatry, the authors said that pregnant women should be encouraged to stop attributing lapses in memory or logical thinking to their growing baby. The findings contradict previous studies that claimed women’s brains decline in size by up to 4 per cent while they are pregnant, potentially leading to worse performance on tests of memory and oral skills. Helen Christensen, author of the latest study, said that the effect was "a myth". Professor Christensen’s team recruited 1,241 women aged 20-24 in 1999 and 2003 and asked them to perform a series of tasks. The women were followed up at four-year intervals and asked to perform the same cognitive tests. A total of 77 women were pregnant at the follow-up assessments, 188 had become mothers and 542 remained childless. The researchers found no significant differences in cognitive(认知的) change for those women who were pregnant or new mothers during the assessments and those who were not. "Not so long ago, pregnancy was ’confinement’ and motherhood meant the end of career aspirations," Professor Christensen said, "but our results challenge the view that mothers are anything other than the intellectual peers of their contemporaries." Cathy Warwick, of the Royal College of Midwives, said that the difficulties of pregnancy and motherhood could explain why some women felt absent-minded or tired. The number of infants in England dying before their first birthday is still greater than in countries such as France, Spain, the Audit Commission says. The health of pre-school children has not significantly improved despite the Government having spent ￡10 billion, directly or indirectly, since 1998 on improving the health of children under the age of 5 in England. Infant death rates have fallen but are "still relatively high" compared with other European countries. According to the first paragraph, some women attributed lapses in memory or concentration to ______.

A. their pregnancy
B. the "baby brain"
C. an unscientific cause
D. changes to their brains