The amount of a specific gene involved in nitrate reduction (narH) was similar in the mouths of pregnant women who later got preeclampsia and those who stayed healthy.

Pregnant women who later got preeclampsia ate about the same amount of nitrate-rich vegetables (like spinach and beets) as women who stayed healthy during pregnancy.

Whether a woman is pregnant or not doesn't seem to affect how well her mouth bacteria can convert nitrate to nitrite.