Today, huge amounts of time and money are spent on genetic research, pre-natal medical counselling, and direct medical intervention such as fertility treatment to help couples who, for one reason or another, have difficulty in conception. While we may like to think of this as an enlightened modern pre-occupation, it is not by any stretch of the imagination. The desire to unlock the mysteries of procreation has occupied man for a long, long time!
In the past, the astrologer employed in the courts of the ruling class and nobility was the first and most important figure upon whom a ruler or noble would depend for counsel to ensure a primogeniture to whom the reins of power or authority would pass.
The traditional or classical astrologer had to be proficient in not only natal delineation, but he had to be skilled in the Arts of Questions and Elections. It was not enough that the astrologer could delineate the possibility of children from the subjects’ nativity, but the question of a successor was so paramount that his aid and direct participation was sought to find the best moment for the act of intercourse to result in the successful generation of a child; and in most cases the desire for a male child. The ancient classical and medieval astrologer, by all accounts, was expected to not only arrange things so that a child of the requisite sex was conceived but also, it was expected that the child would be born at the proper time. This was tantamount to nothing less than a type of astrological genetic counselling!
In his role as ‘family planner’, the astrologer would first delineate the natal charts of the couple, see if child birth was possible, and perhaps see anything that might hinder conception. A couple might also come to him with specific questions which were presented in the form of «interrogations» or horary questions. We can see several of the typical questions that were anticipated in the text of the 9th century Arabic astrologer, Sahl Ibn Bishr.
«… if a man or a woman has asked whether or not he or she will have a child, look at the Ascendant; if there were benefics in it, or if the ruler of the Ascendant was in the Ascendant or in the tenth or in the eleventh or in the 5th, and Jupiter was in the best house from the Ascendant, a child will be born to him; and if the ruler of the Ascendant was in the Ascendant or in the 4th or in the 7th and Jupiter was in a good place from the Ascendant, a child will be born to him with some delay after [the time of] his own question. But if you have found a malefic in the Ascendant or if it aspects it by opposition or by square aspect, and the ruler of the Ascendant was in a bad place, and Jupiter was cadent or in the house of death or under the Sun beams, it signifies few children, and who will live only a short time if there are any…»
« …if the question was about some woman, whether or not she is pregnant and whether or not she will bear a child or whether it would be fortunate for her or not, look at the ruler of the Ascendant and the Moon, which are the significators of children. If you have found the ruler of the Ascendant and the Moon in the house of children, and if the ruler of the house of children is in the Ascendant free from the malefics, say that she is pregnant; and if the ruler of the Ascendant and the Moon have given, i.e. if they have committed, their own disposition to any planet in an angle, there will be a pregnancy, and all the more so if it was received; and if they were joined to a planet cadent from the Ascendant, it signifies loss, and the pregnancy is in vain; and even more so if the Ascendant was a mobile sign or if there was a malefic in an angle, or if the Moon was joined to a malefic, because all of these signify loss…»
« …if you have been asked whether she will bear a male or a female, look at the ruler of the Ascendant and the ruler of the house of children; if they were in masculine signs, there will be a male in her belly; and if they were in feminine signs, there will be a female in her belly; and if one of them was in a masculine sign and the other one was in a feminine sign, look at the Moon’s sign and at the planet to which the Moon is joined; if the Moon was in a masculine sign and was joined to a masculine planet, she will bear a male, but if the Moon was in a feminine sign or was joined to a feminine planet, she will bear a female. And know that Mercury, when it is oriental, i.e. when it is behind the Sun, will be feminine, if God wills!»
He would then «elect» the most auspicious time for conception to occur.
«When you want to elect an hour for intercourse, i.e. when you want to have intercourse with your wife, so that you can beget a male child, let the Ascendant and its ruler and the Moon and the ruler of the house of children be in masculine signs or in a masculine quadrant of the circle in the hour of intercourse, and in that hour you should not put any planet but a masculine one in the Ascendant and in the sign [house] of children. And if you want it to be a female, let these significators be in feminine signs and in a feminine quadrant of the circle…»
Next, the astrologer/physician would cast a chart at the time of conception to determine the length of the pregnancy and find out how long the woman would carry the developing child! The ancient astrologers/physicians believed that fertilization occurred at the time of insemination. They did not know that conception was a process that involved the fertilization of an egg by the male sperm. They simply assumed that the woman’s womb was a protected environment where the man’s «seed» would develop into an infant! Their idea of conception was formed largely from watching plants. It was not until the microscope in the 18th century that physicians learned what true conception was and it was not until the 20th century that physicians learned that true conception might not occur until days after coitus, therefore, it is difficult to credit astrological dicta.
One of the older extant texts containing the astrological instructions for determining the term of a pregnancy and the time of conception can be found in the writings of the Greek astrologer Vettius Valens!
It is difficult in such a short synopsis to go into all the details of the method for calculating the term of the pregnancy. In general it is based on the conception that the degree of the sign in which the Moon is at the time of the infusion of sperm will be the degree of the ascendant in the nativity and that the degree that was ascending at the time of conception will be the same degree as the Moon in the sign it will be posited in the nativity!
Vettius Valens writes,
It is later quoted as the 51st aphorism in the Centiloquium.
«Make the sign occupied by the Moon at the time of birth the ascending sign at the conception; and consider that in which she may be posited at the conception, or the opposite one, as the sign ascending at birth.»
The method postulates that there are three terms of the pregnancy; a least, a middle, and a greatest. The difference between each term is fifteen days. Which term was chosen depended on the position of the Moon in the chart of the conception. The least term is 258 days which was when the Moon was in the degrees of the descending sign above the horizon. The middle term was 15 days more than that, or 273 days and was attributed when Moon was in the ascendant. The greatest term was 15 days more or 289 days, when the Moon was in the degrees of the descendant below the horizon.
Let us say for example, 10º Cancer is rising, then, 10º Capricorn is setting. The conception is that between the setting degree (the least term) moving in the order of the signs to the eastern horizon (the middle term) there are 180º, which are the equivalent of 15 days. Therefore, 30º equalled 2½ days, which can be further divided. 2½ days is 60 hours so 1º was equal to 2 hours. Likewise, from the Ascending sign continuing to move below the horizon in the order of the signs towards the west, those 180 º also equalled 15 days.
So depending on where the Moon was posited, above or below the horizon, then a certain number of days and hours was added to either the least or middle term and that was the length of the pregnancy.
In our example then, if the Moon (for simplicities sake) was at 25º Taurus, then we could find the length of the pregnancy by counting the number of degrees between the descending degree of 10º Capricorn (280º longitude) and subtract that from the degrees of the Moon at 25º Taurus (55º of longitude). Since 55º is smaller than 280º, I add 360º to 55º, which is 415º. Now I can subtract; 415 – 280 = 135º. I can then divide that by 30º, which gives me 4 which a remainder of 15º. Each of those 30º divisions is equal to 2½ days, which gives me 10 days plus 15º, or 10 days and 30 hours, or simply 11 days and 6 hours. This then would be added to the least term of 258 days giving 269 days and 6 hours as the term of the pregnancy.
Just as simply one could of course calculate the degrees between the Ascendant degree and the Moon and subtract the equivalent days from the middle term of 273 days.
I hope the reader realises this is a very simplistic overview of the technique. One finds much more complete instructions in Guido Bonatti’s text book, Liber Astronomiae Tractatus Decimus called, Trutine of Hermes on the Causation of the Length of Pregnancy. This of course, is not the only medieval text discussing the Length of Pregnancy. Dominicus Maria de Novarra wrote an entire manuscript on the subject and found in the Biblioteca Paletina. There are several others from this period also.
What can I say as an astrologer? Does it work? I don’t know as I do not have enough experience in this particular ‘field’ to be able to judge one way or the other. That is the purpose of this short article, to expose this teaching in order to encourage further inquiry!
I do think it is fair enough to speculate in this regard and we should not just dismiss off hand such speculation. For while we may with no certainty say the method does or does not work, it was most certainly a major part of the medieval and classical astrologers ‘bread and butter’.
If such a method was effective and in fact widely practiced, then our predecessors were a long way ahead of us today in their medical ‘technology’ because such a method would be entirely without any deleterious side effects that are always present to some degree with our modern drug, hormone and surgery treatments! It would be an entirely natural solution!
 Horary astrology – casting a chart for the moment of an important question and determining the outcome from identification and particular circumstances of the significators of the querent and question
 Electional astrology – the art of determining the most auspicious moment to do something through examining the astrologicals at certain times
 The Arabian astrologer later known in the West as Zahel (or Zael), a Jew, who served as court astrologer to the governor of Khurasan in the period 820-822 A.D. and later to al-Hasan ibn Sahl (d. 850/851), the vizier of Baghdad during the reign of the caliph al-Ma’mūn (reigned 813-833). Among the 18 books that are attributed to him to have written, five were translated into Latin by 12th century translators in Spain.
 The Introduction to the Science of the Judgments of the Stars, translated from the 12th century Latin text by James H. Holden
 Vettius Valens was a young contemporary of Ptolemy. Valens tells us himself that he was conceived on the 13th of May 119 C.E. and born 9 months later on February 8, 120 C.E. His death is a little more uncertain but he is presumed to have died in the time period 173 – 175 C.E. in his 50’s. His major literary contribution, called the Anthology (Anthologiae) is probably the most massive and comprehensive picture of Hellenistic astrology that exists and not only includes detailed natal methodology but also 125 charts of apparently, Valens own «clients». The Anthology was a major reference work for Byzantine and Medieval Arabic astrologers.
 That is, sign
 That is to say, that the Moon in the nativity is the same as the hour, or ascendant degree, of the conception.
 This work, as the name implies, is a compilation of 100 astrological aphorisms. It was also known by the name Liber Fructus or Book of Fruit and often attributed to Ptolemy. However, this attribution has become very doubtful since a majority of the aphorisms deal with horary, which is a subject Ptolemy appears to disdain and ignore totally in Tetrabiblos. Modern scientific historians also cast much doubt on this attribution and suspect it was rather an ambitious Medieval Arabic writer’s work in the 9th century and assuming Ptolemy’s authorship in order to lend greater authority to his own writings!
 I.e. from conception to birth
 I.e. the ascending degree
 1º = 2 hours
 Dominicus was the student of Marsilio Ficino, the great Florentine Platonist and advisor to the Medicis. He was also reputed to have been friend and associate to Copernicus.