Why You May Need a 3rd Trimester Amniocentesis

Most surrogates are at least familiar enough with an amniocentesis procedure to know that it’s typically done in the early second trimester, if needed. This test is typically completed as part of a diagnostic screening to evaluate the risk that a fetus may have chromosomal abnormalities such as Down syndrome. Knowing this, it can be jarring to hear that a care provider may want you to have one in your third trimester. Administered in the last 12 weeks of pregnancy, the test takes on a different purpose. Here’s a look at what it means to need this invasive test in the weeks leading up to delivery.

The procedure itself is identical no matter which trimester it is performed in. A doctor will use an abdominal ultrasound to guide a long needle into your uterus to extract some amniotic fluid. All care will be taken to not touch the baby with the needle. The entire process takes about 45 minutes and is generally not incredibly uncomfortable for the surrogate.

However, when completed in late pregnancy, the goal of an amniocentesis is not to evaluate the risk of chromosomal abnormalities. Instead, your care provider is likely looking for one of 3 potential conditions. These include:

  1. Detection of uterine infection after a premature rupture of the membranes (if your water broke too early, or you have a small tear causing amniotic fluid to leak.)
  2. Fetal anemia in the instance of a fetus with Rh disease. In some cases, fetal anemia is a life-threatening condition that requires a fetal blood transfusion.
  3. To evaluate lung maturity preceding a premature delivery.

The follow-up and recovery of a late amniocentesis is similar to that of one performed in the second trimester. You may experience some leaking, discomfort at the needle injection site, and general tenderness. Some mild cramping or uterine contractions can also be expected.

Most women will not need for a late-term amniocentesis. If a doctor suggests a third-trimester amnio, you will need to consult with your case specialist and intended parents right away. In most cases, it is not advisable to decline the test at this stage.

Teo Martinez

Teo Martinez is the CEO of Growing Generations, a surrogacy and egg donation agency headquartered in Los Angeles, CA. Educated at both UCLA and Pepperdine University, and with over 15 years of experience working in assisted reproduction, Teo’s background makes him one of the most experienced and accomplished professionals in the field.