Following a previous study linking higher maternal levels of two common chemicals with slower mental and motor development in preschoolers, a new study has found that this effect continues into school age.

The study involved 328 inner-city mothers and their children. The mothers' levels of prenatal urinary metabolites of di-n-butyl phthalate (DnBP), butylbenzyl phthalate (BBzP), di-isobutyl phthalate (DiBP), di-2-ethylhexyl phthalate and diethyl phthalate were measured in late pregnancy. IQ tests were given to the children at age 7.

Children's IQ scores were negatively associated with higher maternal phthalate levels. Among children of mothers with the highest versus lowest levels of DnBP and DiBP metabolite concentrations (the top 25% vs the bottom 25%), IQ was 6.7 and 7.6 points lower, respectively. There were similar associations with processing speed, perceptual reasoning and working memory; DiBP and verbal comprehension; BBzP and perceptual reasoning.

DnBP and DiBP are found in a wide variety of consumer products, from dryer sheets to vinyl fabrics to personal care products like lipstick, hairspray, and nail polish, even some soaps. Since 2009, several phthalates have been banned from children's toys and other childcare articles in the United States.

Although the results are correlational, and don't prove that phthalates are responsible, the researchers recommend that pregnant women avoid storing or microwaving food in plastic containers, and avoid scented cleaning and personal care products (phthalates hold scent). They are also advised not to use plastics labeled 3, 6, or 7.

Factors such as maternal IQ, maternal education, and quality of the home environment, were controlled for in the analysis. The range of phthalate metabolite levels measured in the mothers was not unusual.

[3841] Factor-Litvak P, Insel B, Calafat AM, Liu X, Perera F, Rauh VA, Whyatt RM. Persistent Associations between Maternal Prenatal Exposure to Phthalates on Child IQ at Age 7 Years. PLoS ONE [Internet]. 2014 ;9(12). Available from:

The issue of “mommy brain” is a complex one. Inconsistent research results make it clear that there is no simple answer to the question of whether or not pregnancy and infant care change women’s brains. But a new study adds to the picture.

Brain scans of 19 women two to four weeks and three to four months after they gave birth showed that grey matter volume increased by a small but significant amount in the midbrain (amygdala, substantia nigra, hypothalamus), prefrontal cortex, and parietal lobe. These areas are involved in motivation and reward, emotion regulation, planning, and sensory perception.

Mothers who were most enthusiastic about their babies were significantly more likely to show this increase in the midbrain regions. The authors speculated that the “maternal instinct” might be less of an instinctive response and more of a result of active brain building. Interestingly, while the brain’s reward regions don’t usually change as a result of learning, one experience that does have this effect is that of addiction.

While the reasons may have to do with genes, personality traits, infant behavior, or present circumstances, previous research has found that mothers who had more nurturing in their childhood had more gray matter in those brain regions involved in empathy and reading faces, which also correlated with the degree of activation in those regions when their baby cried.

A larger study is of course needed to confirm these findings.

Older news items (pre-2010) brought over from the old website

Review supports mild memory impairment in pregnancy

A review of 14 studies testing the memory performances of more than 1,000 pregnant women, mothers and non-pregnant women, has found that pregnant women performed significantly worse on some, but not all aspects of the test. The hardest tests for the pregnant women were those that involved new or demanding tasks. Regular, well-practiced memory tasks were unlikely to be affected. The impairment wasn’t large — comparable to the modest deficits you'd find when comparing healthy 20-year-olds with healthy 60-year-olds. However, the impairment was sometimes still evident a year after birth (none looked beyond that point).

[876] Henry JD, Rendell PG. A review of the impact of pregnancy on memory function. Journal of Clinical and Experimental Neuropsychology [Internet]. 2007 ;29(8):793 - 793. Available from:

Effect of pregnancy on cognition depends on fetal gender

An intriguing new study may shed light on the conflicting results reported regarding the effect of pregnancy on cognition. The study, which tracked women throughout pregnancy through to postnatal resumption of menstruation, found that there was a significant effect of the sex of the baby on working memory and spatial ability. Women pregnant with boys consistently outperformed women pregnant with girls on these tests.

[1187] Vanston CM, Watson NV. Selective and persistent effect of foetal sex on cognition in pregnant women. Neuroreport [Internet]. 2005 ;16(7):779 - 782. Available from:

No support for idea that pregnancy affects memory and concentration

A study of pregnant women found many agreed with the popular view that pregnancy affects your memory. However, mental tests during pregnancy and after the birth found no difference between the performance of women who were pregnant and those who were not. It was possible that the affects are too mild to be picked up by the tests, or that the fatigue commonly experienced by women during pregnancy and early motherhood leads women to believe that their memory and concentration are affected.

The research was presented at the British Psychological Society annual conference in Bournemouth.