In other animals the period of gestation and of birth is fixed and definite, while man, on the other hand, is born at all seasons of the year,[962] and without any certain period of gestation;[963] for one child is born at the seventh month, another at the eighth, and so on, even to the beginning of the tenth and eleventh. Those children which are born before the seventh month are never known to survive;[964] unless, indeed, they happen to have been conceived the day before or the day after the full moon, or at the change of the moon. In Egypt it is not an uncommon thing for children to be born at the eighth month; and in Italy, too, children that are born at this period live just as long as others, notwithstanding the opinions of the ancients to the contrary. There are great variations in this respect, which occur in numerous ways. Vestilia, for instance, who was the wife of C. Herdicius, and was afterwards married, first, to Pomponius,[965] and then to Orfitus, very eminent citizens, after having brought forth four children, always at the seventh month, had Suillius Rufus at the eleventh month, and then Corbulo at the seventh, both of whom became consuls; after which, at the eighth month, she had Cæsonia, who became the wife of the Emperor Caius.[966] As for children who are born at the eighth month, the greatest difficulty with them is to get them over the first forty days.[967] Pregnant women, on the other hand, are in the greatest danger during the fourth and the eighth month, and abortions during these periods are fatal. Masurius informs us, that L. Papirius, the prætor, on one occasion, when the next but one in succession was urging his suit at law, decided against him, in favour of the heir,[968] although his mother declared that her period of gestation had lasted thirteen months—upon the ground that it did not appear that there was any fixed and definite period of gestation.[969] CHAP. 5. (6.)—INDICATIONS OF THE SEX OF THE CHILD DURING THE PREGNANCY OF THE MOTHER.[970]