Is pregnancy brain real? Comparison of dual task cost during overground walking in pregnant versus control women

Many pregnant women report that their memory is impaired compared to non-pregnancy, but results of studies of cognitive abilities are mixed. The effect of pregnancy on dual tasking, or performance of two tasks simultaneously, has not been studied, however.

What is the effect of walking overground at a self-selected speed while also performing a cognitive task on gait and cognitive performance during 3rd trimester of pregnancy compared to non-pregnant controls?

A total of n = 22 3rd trimester pregnant women (mean 33.3 ± 3.3 weeks gestation, age 32.1 ± 4.7 years) and n = 21 non-pregnant controls (age 31.9 ± 3.3 years) were recruited to participate. All participants performed single task walking on a GAITRite gait analysis system and performed three cognitive tests while walking: serial 3 and 7 subtraction tests and a phoneme monitoring test. Participants completed the same assessments while seated and order of the testing was counterbalanced. Dual task cost (DTC) was calculated using the formula (Single task score - Dual task score)/Single task score)*100. Independent t-tests or Mann Whitney U tests were used to compare the two groups depending on normality of data.

There were no significant differences in cognitive test performance between control and pregnant women while walking or seated (p > 0.05). There were no significant differences between groups for DTC during any cognitive tests, but DTC was significantly greater for walking velocity in pregnant women compared to controls for serial 3 (p < 0.001) and serial 7 (p = 0.005) but not phoneme monitoring (p = 0.061).

Pregnant women had elevated cost of dual tasking, though the decrements were not in cognitive tests but in gait, specifically with greater DTC of walking velocity. This suggests that pregnant women modify their walking velocity to preserve cognitive function during activities requiring focus on both cognitive and physical tasks.