First Trimester – Each pregnancy is divided into 3 trimesters:
- the first trimester is from week 1 to the end of week 12.
- the second trimester is from week 13 to the end of week 26.
- the third trimester is from week 27 to the end of the pregnancy.
The first trimester
You missed your period. Your breasts are sore and you’re exhausted. You take a home pregnancy test and a plus sign appears. Hurray! You’re pregnant! Time to get “official” confirmation at the doctor’s office with an ultrasound exam.
What to expect at your exam
Your first ultrasound, also known as a sonogram, will take place when you’re around 6 to 8 weeks pregnant.
At this stage, your baby is very small and your uterus and fallopian tubes are closer to your birth canal than to your abdomen, so your doctor will conduct the test transvaginally to get a clearer picture. The test is painless. Your Radiologist will place a thin, wand-like transducer probe, which transmits high-frequency sound waves through your uterus, in your vagina. The sound waves bounce off the fetus and send signals back to a machine that converts these reflections into a black and white image of your baby. It will be hard to see much in this first snapshot, but a clearer photo will come around 13 weeks, which is the ideal time to share your exciting news.
Why is it important ?
Your Radiologist listens for your baby’s heartbeat and estimates baby’s age by measuring his length from head to bottom; the baby is tiny in the first trimester and is growing about a millimeter a day. From this test, your doctor will be able to determine a more accurate due date and track milestones during your pregnancy.
Your Radiologist will also rule out a tubal (ectopic) pregnancy, which is when the fetus grows in the fallopian tube instead of the uterus. (Don’t worry: This occurs only 1 percent of the time.)
And your doctor will also be able to tell if you’re pregnant with twins.
All pregnant women are offered a nuchal translucency (NT) test, performed between 11 and 13 weeks, and this involves another ultrasound. The NT evaluates your risk of having a baby with Down syndrome, trisomy 18 (another chromosomal abnormality), or certain heart defects. In this two-part exam, a blood test measures levels of certain hormones and proteins in your body, and an ultrasound determines the thickness at the back of baby’s neck (increased thickness indicates that he may be at risk for birth defects such as Down syndrome and trisomy 18).