Day 65 of 280, first trimester
You are 9 weeks and 2 days
The muscular diaphragm that will eventually let your baby breathe, and hiccup, is developing now.
215 days until your due date
As your baby's lungs develop in the chest, there's nothing yet separating them from the stomach, liver, and bowel in what will become the abdomen.
In adults, the muscular diaphragm separates the chest from the abdomen. When we breathe, the diaphragm moves down and the ribs expand outward, drawing air into the lungs.
Your baby's diaphragm forms from four folds of tissue, first seen around this week. They gradually grow inward and fuse, closing the gap by the end of the week.
In the middle of the diaphragm are openings for the esophagus to the stomach, the aorta (the main artery to the body), and the inferior vena cava (the main vein returning blood from the lower body). As pregnancy goes on, muscle fibers gradually strengthen the diaphragm, which later lets your baby make breathing movements.
Time to think about
Screening and diagnostic tests
It's useful to know about the screening and diagnostic tests available in the coming weeks. Your doctor will talk through the pros and cons of each. Some abnormalities may be picked up at the 18–22 week scan.
- Screening tests show the risk of a particular condition but don't confirm your baby has it. For example, a Down syndrome screening result of 1:200 means a 1 in 200 chance your baby is affected, not that he definitely has the condition.
- Diagnostic tests: if screening shows a high risk of a chromosomal abnormality, you'll be offered a diagnostic test, such as amniocentesis or chorionic villus sampling (CVS), which gives a definite answer.
Focus on
Twins: Twin tests
If you're expecting twins or more, blood-based screening for Down syndrome can be misleading, because it measures AFP (alpha-fetoprotein) and other markers, which are much higher when there's more than one baby. Your best option is the nuchal translucency scan at 11–14 weeks.
Explainer
The nuchal translucency scan
This scan measures the thickness of the fluid under the skin at the back of the baby's neck. A high level may mean a greater risk of Down syndrome. It's the most accurate way to screen for Down syndrome.
Appointments and key dates around now
- Booking appointmentUsually between 8 and 12 weeks
Read the full 9 weeks pregnant guide
This is general information based on NHS guidance, not medical advice, and every pregnancy is different. Talk to your midwife or GP about anything that worries you. If your baby's movements slow down or change, or you have bleeding, severe pain or leaking fluid, call your maternity unit straight away. In an emergency, call 999.