Since the day humans appeared on earth, continuation of this race involved physical union of man and woman. With time, this union evolved into elaborate rituals and refined institution like marriage. Long ago, our ancestors devised certain norms and taboos in order to ensure sanctity in the relation between man and woman. They had complete control over their sexual drives while they honoured the tradition of their clans regarding selection of mate.
For the benefit of the individual and the society as a whole, it is imperative that a thing should be done at the right and auspicious moment. Only then such a thing could be favourable for the doer. The same thing applies to the physical union of man and woman. Scriptures have very clearly opined in this regard. Accordingly, after the menses, intercourse should be carried out on any auspicious moment on days except the fourth, eighth, fourteenth and moonless and full moon nights.
Time from the appearance of menses, up to the sixteenth day is known as Ritukaal for a woman. During this period, a woman is especially in heat and an intercourse without the use of contraceptives is sure to result into a pregnancy. The first four nights of this period are forbidden period. During this time, dark-coloured blood with peculiar smell flows. Contact with such a woman is harmful for both the partners physically as well as psychologically.
Besides the first four nights, intercourse is prohibited on the eleventh and thirteenth nights also. Remaining ten nights are completely conducive for the intercourse. Even on these ten days, if a festival or full moon and moonless nights fall, intercourse must be postponed. Positions of the Sun and the Moon on these days are such that their combined effects influence profoundly the human psychology and the movement of fluids in the body. An intercourse involves perfect streamlining of bodily fluids and if it is carried out on any of these days, adverse effects on the body cannot be ruled out. Even a child that a woman bears, on full moon and moonless nights may carry these defects like having two heads, a tail, four hands, joint bodies or psychological defects like being cruel, daredevils, murderers etc. Even the birds and animals enjoy intercourse at a prefixed time set by the nature. The male bird and animal scent their female counterparts to judge whether they are really ready to conceive or not. They proceed to intercourse only when the female is in oestrous.
Nights have been fixed as the precise period for enjoying intercourse. Even at night, time from nine to twelve is most conducive that to at least one and half-hours after taking dinner. Intercourse is strictly prohibited at twilight of dawn and dusk. It has a spiritual as well as physical significance. An intercourse carried out at unfavourable time always leads to the birth of a demonic child. Ravan is one such profound example. Despite being a Brahmin by birth, he developed demonic virtues for his parents had an intercourse at twilight.
In the modern era, when girls are faring well in almost every field and are no less than the boys, there are many people who long for a son. In their effort to have a son, such people keep on producing many girl children and blame the destiny for their condition. Practice of patience and recognition of appropriate time is important for such people who want to have a son. Such people must carry out intercourse on the even days after the menses that is they should carry out intercourse on sixth, eighth, tenth, twelfth, fourteenth or sixteenth day after the menses. Intercourse on the odd days that is fifth, seventh, ninth, eleventh, thirteenth and fifteenth days after the menses is favourable for having a girl child. It is said that during an intercourse, excess of seminal fluid leads to a boy child whereas excess of Ruj (female fluid of excitement) leads to the birth of a girl child.
It is said that after the menses are over, a peculiar kind of excitement (cupid wave) overtakes the woman. This wave rises and falls on alternate days. On even days, cupid wave subsides whereas on odd days, it surges. Thus, having intercourse on auspicious moments in auspicious days not only maintains sanctity and good health that also helps one to get a desired offspring.