As part of participants' prenatal care, they will undergo several ultrasound examinations to assess structures related to the pregnancy (the fetus, the placenta, the tumor, amniotic fluid volume, measurements of blood flow, etc.). Information obtained from these ultrasound examinations will be collected for the purposes of research. The ultrasounds are being performed as part of routine care, not for research purposes. Similarly, information about the newborn (gestational age at delivery, birthweight, blood count, need for resuscitation, length of stay, complications) will be collected as part of the study. No procedures will be performed on participants or their babies as part of this research.