Maternal cognitive functioning in pregnancy and its association with gestation, endocrine factors and fetal sex: A longitudinal study in women from early pregnancy to the postpartum period

Research addressing the effects of maternal cognitive changes during pregnancy has yielded equivocal findings with both confirmatory and negative results appearing fairly equally in the literature. In an attempt to evaluate and further test this phenomena, 45 women where tracked from early pregnancy until postnatal resumption of menses. An age and education matched control group of 45 non-pregnant women were tested concurrently. At each of the five test sessions participants completed a battery of cognitive tests. Results showed no effect of pregnancy on any of the dependent measures, with pregnant women performing no worse than control women on the nine cognitive tasks administered. One possible explanation for this negative finding (and the research ambiguity in this area) could be linked to the sex of the fetus. When fetal sex was considered, a selective and persistent effect on maternal cognitive function was observed. Those women pregnant with sons consistently outperformed women pregnant with daughters on the tests of working memory. On several other cognitive tests fetal sex was unrelated to maternal performance. This effect was evident from the first test session and persisted until the final session and was unrelated to sleep, mood and demographic measures. This result suggests either a fetal-derived factor that differs in type or concentration between male and female fetuses may influence the mothers' cognition both during pregnancy and into the postnatal phase. Or, alternatively, qualities inherent to the mother may be related to both her propensity to deliver a specific sex and her cognitive profile. Both possible explanations are discussed.