Mama, please check with your OB muna about this, better safe than sorry sa ganitong concerns, lalo na at gaano ka-specific ang amount. From what a few of us talk about, pineapple is okay in normal amounts (like eating the fruit itself), pero drinking liters ng juice in one day is isang ibang story, that's too much sugar and acidity para sa katawan mo, especially ngayon na 37 weeks ka na. Your doctor knows your health best, so let them guide you kung ano talaga ang safe para sa iyo at sa baby. Take care, mama!