Placenta previa. Placenta previa is more likely with an anterior placenta. (This would be seen at your anatomy ultrasound when you're about 20 weeks pregnant.) If the placenta sits over the cervix ...

It claims that an anterior placenta (attached to the front ... and trisomy 13 (Patau syndrome). Anatomy scan: Done between 18 and 20 weeks, this second-trimester ultrasound takes an in-depth ...