First Trimester Screening: The Complete Guide
The first trimester of pregnancy brings your first routine scans and screening tests. Understanding what is offered, when it happens, and what the results mean helps you feel informed and in control. This complete guide walks you through everything to expect between weeks 10 and 14.
Table of Contents
Your Booking Appointment
Between weeks 8 and 12 you will have a booking appointment with a midwife. She will take your medical history, discuss your care options, arrange blood tests (for blood group, infections, and anaemia), and offer screening for conditions such as sickle cell and thalassaemia if relevant. This is also your chance to ask questions about your pregnancy and the tests ahead.The Dating Scan
The dating scan, also called the 12-week scan, is offered between 11 and 14 weeks. The sonographer checks your baby's heartbeat, confirms your due date by measuring the baby from head to bottom (crown-rump length), and checks whether you are carrying one baby or more. This scan also looks at the nuchal translucency if you choose combined screening.Screening Tests Offered
At this stage you may be offered the combined screening test, which estimates the chance of Down syndrome, Edwards syndrome, and Patau syndrome. This involves a blood test and a measurement of fluid at the back of your baby's neck. You can also opt for a non-invasive prenatal test (NIPT), available privately and increasingly on the NHS for higher-risk results. Screening is optional, and you can choose to have some, all, or none of the tests.Understanding Your Results
Screening results give a probability, not a diagnosis. A lower risk result (for example, 1 in 5,000) means the chance is low, but not zero. A higher risk result (1 in 150 or higher for Down syndrome) means you will be offered further testing. Remember that most women receive a lower risk result. Your midwife will explain your numbers and answer any questions.FAQ
### Can I decline first trimester screening?Yes. All screening is optional. Your midwife will explain what each test involves, and you can decline any or all of them without it affecting the rest of your care.
What if my dating scan shows a different due date?
This is common. The dating scan is more accurate than calculating from your last period, so your due date will usually be adjusted based on the scan measurement.
This article is for informational purposes only and does not constitute medical advice.
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