The consumption of kombucha is not recommended from the 3rd trimester onwards due to the possible content of heparin.
Jessica Martínez Leal, Lucía Valenzuela Suárez, Rasu Jayabalan, Joselina Huerta Oros & Anayansi Escalante-Aburto (2018) A review on health benefits of kombucha nutritional compounds and metabolites, CyTA - Journal of Food, 16:1, 390-399, DOI:10.1080/19476337.2017.1410499