Effects of gender on fetal cortical development: a secondary analysis of a prospective cross-sectional study.

Objectives: The primary objective was to evaluate the effects of fetal sex on fetal cortical development in low-risk pregnancies. Secondary objective was the evaluate the impact of gestational age.

Methods: This was a secondary analysis of a prospective cross-sectional study on low-risk fetuses undergoing fetal neurosonography between 19 and 34 weeks of gestation. The depth of Sylvian Fissure (SF), Parieto Occipital Fissure (POF) and Calcarine Fissure (CF) were evaluated and related to fetal sex. Neurosonographic variables were normalized for fetal head circumference and expressed as multiple of the median (MoM).

Results: A total of 344 fetuses were considered (173 male, 171 female). The baseline characteristic of the two groups were similar except a higher birthweight present in male fetuses (p=0.044). The depth SF (p=0.023) CF (p=0.014) and POF (p=0.046) showed significantly higher values in male fetuses when all the gestational age range was considered. However, when data were controlled for gestational age, these differences resulted significant only after 28 weeks.

Conclusions: Differences in cortical development related to gender occur after 28 weeks of gestation with an increase depth of SF, POF and CF in male fetuses.