Why does every simple question have to get personal? Firstly, Bombmaniac, his question is indeed valid. Ess HaBatzir was succos time (Chag HaAsif) and without modern refrigetation, presumably your choice was between drinking your grape juice or fermenting it into wine (points if someone gets in the interesting R’ Moshe about this).
I think Pesach time they takeh didn’t have grape juice.
And Bomb, even if someone doesn’t chas vchalilah think before they post, do you have to be obnoxious? Play nice.
But as to the OP’s question, if you use a min. shiur of a revis – of 3 oz, and drink only Rov , you’ve got only 1.6 Oz per cup. Of course, others hold even a cheekful suffices, and then you could drink only an oz (each individual is different). So over the entire four kosos, they only drank about five oz – nothing any OB would get excited over, – once a year! Kiddush, if you are being yotzeh – they had a sip.
Though the miscarriage rate was much higher then, as want infant and child mortality. Whatever we can do to prevent miscarriages, we certainly should do.