Praeterea ego de partu humano, praeterquam quae scripta in libris legi, hoc quoque usu venisse Romae comperi: feminam bonis atque honestis moribus, non ambigua pudicitia, in undecimo mense post mariti mortem peperisse, factumque esse negotium propter rationem temporis, quasi marito mortuo postea concepisset, quoniam decemviri in decem mensibus gigni hominem, non in undecimo scripsissent; sed divum Hadrianum causa cognita decrevisse in undecimo quoque mense partum edi posse; idque ipsum eius rei decretum nos legimus. in eo decreto Hadrianus id statuere se dicit requisitis veterum philosophorum et medicorum sententiis.
(Aulus Gellius, Noct. Att. 3.16.12)
Furthermore, besides what I have read in books about human gestation, I also heard of the following case, which occurred in Rome: A woman of good and honourable character, of undoubted chastity, gave birth to a child in the eleventh month after her husband’s death, and because of the reckoning of the time the accusation was made that she had conceived after the death of her husband, since the decemvirs had written* that a child is born in ten months and not in the eleventh month. The deified Hadrian, however, having heard the case, decided that birth might also occur in the eleventh month, and I myself have read the actual decree with regard to the matter. In that decree Hadrian declares that he makes his decision after looking up the views of the ancient philosophers and physicians.
* XII Tab. iv. 4, Schöll. The fragment is not extant, but it is cited also by Ulpian, Dig. xxxviii. 16. 3. 11: post decem menses mortis natus non admittetur ad legitimam hereditatem.
(tr. John C. Rolfe, with his note)