It is known that Vanswieten gave the following advice to Empress Maria Theresia who was childless in the beginning of her married life. “Ego vero censeo, vulvam Sanctissimae Majestatis ante coitum diutius esse titillandam.”
[CZ] Hensen (Physiologie der Zeugung) concludes from statistics compiled from 284 cases wherein the day concarnationis was known, that the greatest number of conceptions follows the act practised in the days immediately after menstruation. The chances of conception following the act practised during menstruation are increased the nearer the catamenial period is approaching its end. The number of conceptions after the act practised before menstruation, Hensen found to be the smallest.
[DA] In a general way Hesiod advises never to practise concarnatio on the return home from a funeral, but rather after having enjoyed a good comedy, for the semen transfers cheerfulness as well as sorrow and other affections to the offspring. For the same reason concubitus should be avoided when in a state of intoxication. Diogenes said to a stupid boy: “My son, thy father was drunk when thy mother conceived thee.”
[DB] Noirot found that the healthiest and strongest children are those conceived in the spring, the time of the rejuvenation of nature.
Oettinger found that liaisons produce an abnormally large proportion of females, incestuous unions of males.
Westermark says that among exogamous peoples the female birth rate is often excessively high.
[DC] Soranus goes so far as to claim that conception cannot ensue if initus is not desired and longed for by the woman. Just as the man can have no ejaculation, or rather erection, without desire, so is conception impossible without it in the woman. Just as food, taken without appetite or with disgust, will not be properly digested, so the sperma can not be received by the womb, if inclination and lust are wanting during concarnatio.
This opinion is not borne out by experience, for we find that pregnancy does take place after concarnatio while the woman is in a natural or hypnotic sleep, in a chloroformed state, in drunkenness and in rape. These facts prove that pregnancy may follow concarnatio where the woman did not experience the least degree of libido.
But even if conception be possible without libido, the lack of the latter is a great impediment to impregnation.
[DD] Roubaud says that, initus interruptus causes in the woman voluptuous excitation without allowing the reception of the spermatic fluid into the organs. The desire and the copulative-voluptuousness awaken the sensibility of the womb and prepare it to receive the normal excitation of the sperma. If its arrival fails, the uterine sensibility, awakened by the erotic sensibility, reacts upon the mobility in a confused manner and causes unsuitable and irregular motions. If these manoeuvres are often repeated the woman eventually becomes a nervous wreck.