Visual evoked potentials in pregnancy
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Date
1999
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Abstract
Pregnancy is a period when the estrogen/progesterone ratio rises considerably because of the passage of estrogen from the placenta. These changes in the level of estrogen during pregnancy increase the sensitivity of the central nervous system to cathecholamines. As a result, the sensitivity of the receptors in both the visual cortex and the inner plexiform layer of the retina to dopamine increases, and transmission in the optic pathways becomes faster. Inspired by this knowledge, we studied monocular pattern-reversal visual evoked potentials (PRVEPs) in both eyes of 30 pregnant women in the first trimester and 30 healthy nonpregnant women in the reproductive age. Mean P100 latency of pregnant women was significantly shorter than mean P100 latency of nonpregnant women (p<0.001). Mean P100 amplitude values were higher in pregnant women, although not statistically significant (p>0.05). Plasma estrogen and progesterone levels of pregnant women showed a negative correlation with PRVEP latencies, but a positive correlation with PRVEP amplitudes. In conclusion, this study supports the impression that changes in the levels of sex steroids affect the formation of PRVEPs by their actions on the central nervous system. The increase in estrogen during pregnancy seems to facilitate neural transmission in the optic pathways. Rise in the estrogen-progesterone level might be responsible for the shorter PRVEPs latencies in pregnant women.