The placenta protects the fetal circulation from anxiety-driven elevations in maternal serum levels of brain-derived neurotrophic factor

Brain-derived neurotrophic factor (BDNF) plays crucial roles in brain function. Numerous studies report alterations in BDNF levels in human serum in various neurological conditions, including mood disorders such as depression. However, little is known about BDNF levels in the blood during pregnancy. We asked whether maternal depression and/or anxiety during pregnancy were associated with altered serum BDNF levels in mothers (n=251) and their new-born infants (n=212). As prenatal exposure to maternal mood disorders significantly increases the risk of neurological conditions in later life, we also examined the possibility of placental BDNF transfer by developing a new mouse model. We found no association between maternal symptoms of depression and either maternal or infant cord blood serum BDNF. However, maternal symptoms of anxiety correlated with significantly raised maternal serum BDNF exclusively in mothers of boys (r=0.281; P=0.005; n=99). Serum BDNF was significantly lower in male infants than female infants but neither correlated with maternal anxiety symptoms. Consistent with this observation, we found no evidence for BDNF transfer across the placenta. We conclude that the placenta protects the developing fetus from maternal changes in serum BDNF that could otherwise have adverse consequences for fetal development.

Automated summary

Maternal depression during pregnancy did not show an association with serum BDNF levels, while maternal anxiety was correlated with increased BDNF in mothers of male infants. Male infants had lower serum BDNF levels compared to female infants, but this was not related to maternal anxiety. The study did not find evidence of BDNF transfer across the placenta, indicating the placenta's protective role against maternal changes in BDNF levels.