First-Trimester Ultrasound Assessment of Velamentous Cord Insertion

The goal of this observational study is to learn whether a short ultrasound assessment during the routine first-trimester pregnancy scan can identify velamentous cord insertion, an abnormal location where the umbilical cord joins the placenta. The study will include pregnant participants aged 18 years or older with a singleton pregnancy who attend first-trimester combined screening between 11+0 and 13+6 weeks of pregnancy. The main questions it aims to answer are: * How often can the placental cord-insertion site be successfully classified within a 3-minute assessment? * How accurately does first-trimester ultrasound identify velamentous cord insertion compared with examination of the placenta after delivery? Participants will: * Attend their usual first-trimester ultrasound examination. * Have an additional transabdominal ultrasound assessment of the placental cord-insertion site after the routine scan, taking no more than 3 minutes. * Allow the study team to review relevant pregnancy and birth records. * If they deliver at the study hospital, allow examination of the placenta after delivery as part of the study reference standard.

Inclusion Criteria: * Pregnant participants aged 18 years or older with a singleton pregnancy * Attendance for first-trimester combined screening at 11+0 to 13+6 weeks * Capacity to provide written informed consent Exclusion Criteria: * Multiple pregnancy * Declined or withdrawn consent