No after-influence can ever compensate for mistakes made at this time.[9] What is true of alcohol is equally true of other potent drugs and poisons, which should all be avoided so far as possible during pregnancy because of the harmful influence they may directly exert on the embryo.

Hygiene is better than drugs, and care should be exercised in diet, which should by no means be excessive.

It is a mistake to suppose that the pregnant woman needs considerably more food than usual, and there is much reason to believe not only that a rich meat diet tends to cause sterility but that it is also unfavorable to the development of the child in the womb.[10] How far, if at all, it is often asked, should sexual intercourse be continued after fecundation has been clearly ascertained?
This has not always been found an easy question to answer, for in the human couple many considerations combine to complicate the answer.

Even the Catholic theologians have not been entirely in agreement on this point.

Clement of Alexandria said that when the seed had been sown the field must be left till harvest.