Prenatal exams during the first trimester
The pregnancy test has come back positive and now what?
It's time to make an appointment with the gynecologist and to start making you tests.
We tell you which are and what are they for.
It is recommended to visit the gynecologist and / or the midwife every 4 weeks to week 36, every 2 weeks to week 38 and weekly until the end of pregnancy.
On this first visit, you will be prescribed folic acid, iodine and iron supplements. You too will weigh and you will take the tension.
In the first trimester the recommended tests are:
First trimester ultrasound
It is done between week 10 and 14 of pregnancy, usually in week 12.
This ultrasound is used to:
- Confirm the proper embryo implantation
- Determine if it is a multiple pregnancy
- Confirm the gestational age and calculate the possible due date
- Measure the nuchal fold, also known as nuchal translucency
First trimester screening
The nuchal translucency measurement that is measured with first trimester ultrasound is part of a 1st trimester combined test. Also known as triple screening or triple test.
It allows the detection of pregnant women who have a high risk of having a baby with a chromosomal disorder, such as Down syndrome (trisomy 21) and two other trisomies such as 13 and 18.
It is important to clarify that having a positive screening test does not indicate that there is a chromosomal disorder, but only higher risk to suffer it.
To get a definitive answer, a prenatal diagnostic test is needed, such as chorionic villus sampling or amniocentesis which are invasive tests with an increased risk of miscarriage.
Three parameters are taken into account for the first trimester screening:
- The nuchal translucency. Is a liquid space that babies have on the nape, behind the skin and that it is increased in babies who have chromosome problems.
This edema disappears around week 14, so this study is performed between week 11 and 13.
- Mother's age
- Blood test:
- Female hormone 17 beta estradiol (BetaHCG) that is produced by the mother
- PAPP-a hormone that is produced by the baby
With these three parameters, and with an algorithm, it can be achieved detect more than 85% of fetuses at risk chromosome problems such as Down syndrome.
High risk = values <1/250 (for example, 1/100)
Low risk = values> 1/250 (for example, 1/10000)
If he risk is high, the mother is offered the possibility of carrying out a invasive diagnostic test as a chorionic villus sampling or amniocentesis.
Non-invasive prenatal test
This is one alternative to first trimester screening which is capable of detecting up to 99% of the main trisomies such as Down syndrome.
It is made from a simple blood test from week 10, and not valid for twin pregnancies.
It consists of a sequencing that allows analyze fetal DNA in the mother's blood and compare it with maternal DNA to detect certain anomalies with great precision and reliability.
It is not funded, and its cost ranges from 500-800 euros depending on the laboratory
Like the first trimester screening not a diagnostic test. If the test is positive, a prenatal diagnostic test, such as chorionic villus sampling or amniocentesis, will be necessary.
Urine and blood analysis
One per quarter.
In addition to being analyzed typical values such as glucose or hemoglobin, the presence of antibodies to assess the mother's immunity status against certain infectious diseases such as hepatitis B and C, rubella, HIV, syphilis or toxoplasmosis.
The indirect Coombs test also determines the blood group and Rh of the mother.
It is important to know this to avoid a possible Rh incompatibility between the pregnant woman and her baby.
They mainly serve to detect urine infection, but they also detect the presence of glucose, protein and creatinine.
- How do you know if you are pregnant
- Everything you need to know about pregnancy tests
- What is the purpose of measuring the nuchal fold of the fetus?