Или в Великий Пост.

Тоже проказа, да?

Конечно. Грех ведь.

Еще дети, зачатые женщинами в дни очищения, бывают рыжеволосыми.

Да, с грехом понятно, я просто не был уверен, что нет каких-либо других заболеваний, которые бы могли всплывать в этой связи. Спасибо за дополнение.

Насколько я помню, где-то еще говорится, что большие родимые пятна (в пол-лица и пр.) -- знак того, что ребенок зачат во время месячных. Ну, или того, что мать смотрела на огонь или кровь.

Да, "мать смотрела" связано с представлением о фантазии, о силе воображения, как о влияющем на действительность.

I do not think that is quite correct. There was no consensual "medieval" view. Though it was realized that such an intercourse leads to no good, medical consequences were not worked out in detail. Most physicians believed that such conception is simply impossible. This topic is very much at the center of debate about ordination of women, so I just stole the following excerpt from one of such sites (http://www.womenpriests.org/body/ranke.asp). It goes on and on and on.

...Whereas Philo believed that the virulent effects of menstrual blood on semen were such that conception could not occur, the Roman naturalist Pliny (d. AD 79) condemned sexual intercourse with a menstruating woman because any children conceived during menstruation were sickly, afflicted with purulent blood serum, or stillborn (‘Historia naturalis’, 7, 15, 87).In the opinion of such Fathers of the Church as Clemens Alexandrinus and Origen (c. 200) and Jerome (c. 400), children conceived during menstruation were born handicapped. Jerome: ‘If a man has intercourse with his wife at this time, leprous hydrocephalic children are born of this conception, and the effect of the tainted blood is such that the contaminated bodies of both sexes become either too small or too large’ (‘Commentary on Ezekiel’, 18, 6).

‘He that has intercourse with his wife during her period’, warned Archbishop Caesarius of Arles (d. 542), ‘will father children that are leprous, epileptic, or possessed by the Devil’ (Peter Browe, 'Beiträge zur Sexualethik des Mittelalters’, p. 48). Isidore of Seville (d. 636), whose encyclopedic ‘Origines’ was widely read for centuries, wrote of menstrual blood: ‘After contact with it fruits cannot germinate, flowers wilt, grasses wither . . . iron rusts, bronze turns black, and dogs that partake of it develop rabies’ (ibid., p. 2). Like Philo, he believed it so ‘corrupted’ semen that menstruation precluded conception. Abbot Regino of Prüm (d. 915) and Burchard of Worms (d. 1025) laid it down that priests in the confessional should question penitents on the subject of intercourse during menstruation.

You get the picture. One group claims it impossible, another blames everything on it, from hydrocephaly to leprosy. Things changed little in the medical profession since the Middle Ages.

Ясно. Иными словами, по мнению большинства, греховность соития как-то должна была сказываться на потомстве, но строгого соответствия между конкретным грехом и конкретным же заболеванием не было.