Justinian, Digest of Roman Law 19.2.19.7

si quis mulierem vehendam navi conduxisset, deinde in nave infans natus fuisset, probandum est pro infante nihil deberi, cum neque vectura eius magna sit neque his omnibus utatur, quae ad navigantium usum parantur.

If someone has taken a women on his ship as a passenger, and she has then given birth to a baby on board the ship, the judgement to make is that nothing is owed for the baby, since its fare is not large [or something like ‘its transportation is not a big deal’?] and it does not make use of those facilities which are provided for the use of the passengers.