Wigra Kesje, Pregnancy Spirits

Wigra kesje, pregnancy spirits, are a set of benevolent and malevolent demons affecting pregnancy. According to the tale, women can attract good spirits eating vegetables and bakery products, avoiding alcohol and fruits and regulating meat consumption. Also, eating a special herbal decoction can attract benevolent demons even before sex, increasing the probability of getting pregnant.
Malevolent spirits influencing children in the womb will lead to a dangerous pregnancy, increasing the probability for mothers to die in childbirth and for children to be sick and generally more inclined to be tainted by abyssal corruption. Rumour has it that a woman once gave birth to a demon, dying soon after; the dark creature grew instantly to the size of an adult and destroyed the village.
Benevolent spirits, instead, protect the mother from being sick, decrease general discomforts and ensure a healthy, strong child. They also make the breasts grow and help to feed the baby, enhancing breast milk nutritional properties.

Scientific Basis

Doujatar scholars became aware of this tale and some of them proposed a possible scientific explanation for it.
Children are healthier when their mother follows a better diet, which explains every recommendation in the myth, expect avoiding fruits. About these, scholars claim that those collected in the wilderness, which constitute the majority of fruits consumed in Dark Lands' villages, can be tainted with abyssal corruption, with the obvious result of a dangerous pregnancy.
They deny the existence of such spirits since demons are not interested in pregnancy at all. On this topic, someone points out nobody knows all possible demons in existence, but scholars are notoriously stubborn and the rest of the theory makes sense. They counter-argue that if such demons existed in the close Dark Lands, then they would have spread in Doujate too by now, but they didn't.
They also rule out the possibility of a woman giving birth to a demon. They are different things, they claim, it would be like for an elf to give birth to a sirenid, it does not make any sense at all.