I’m geeking out. I’ve been geeking out for a week. Come geek out with me.
Personal update
The Jorgensen family has some really exciting news: we are welcoming another Baby Jorgensen! She’s 14 weeks gestation right now, and we are really enjoying getting to know her.
Because of this, I recently got an NIPT. Cue the geeking out.
The NIPT
One test that pregnant folks might be offered is the NIPT (non-invasive prenatal test). This test screens for different genetic setups that aren’t typical (trisomy, microdeletions, Turner syndrome, etc.) but do happen. Some of these conditions are life-limiting. Since I work primarily in bereavement, I work with a lot of families whose babies are experiencing these atypical genetic setups, and when I’m pregnant, I get anxious about those things. Basically, because I work so frequently in grief settings, sometimes it’s difficult for me to remember that pregnancies go well.
So, I’m grateful that the NIPT exists, to give me a heads up if a baby has a higher likelihood for a particular condition. The test can’t check for all conditions, and it doesn’t say if a baby definitely has a certain condition, but it does say if the baby has a higher or lower likelihood of having certain conditions; based on that information, you can choose whether to do further testing. This is the difference between a screening test – which just looks at general likelihoods – and a diagnostic test – which looks specifically for whether a baby has markers a particular condition.
For folks like me who like to have information and plan for all scenarios, NIPT can give some valuable information pretty early in pregnancy. (Check out ACOG’s guidance on the NIPT here.)
NIPT works in an AMAZING way. Let me tell you about it.
How the NIPT works
How on earth can I get a blood draw at 9-10ish weeks pregnant and then find out about my baby’s chromosomes?
The answer is cell-free DNA.
When you’re pregnant, once a placenta has formed, the placenta releases fetal DNA (baby’s DNA) into the maternal plasma (mom’s blood). This DNA isn’t attached to a particular kind of cell, hence the name. But, that DNA is prominent enough in the maternal bloodstream that taking some blood from mom’s arm (at least 9 weeks into gestation, and some providers say at least 10) means we can see an analyzable amount of baby’s DNA. (For more but still digestible info, see Medline’s article on the topic.)
Whenever someone’s DNA is present in someone else’s body long term, that’s called “chimerism.” This particular type of chimerism, where a child’s DNA is in their mother’s body, is called “fetal microchimerism.” There are a lot of studies being done on how this might change a mother’s health (possibly for the better in later thyroid issues, maybe a slightly higher chance of preeclampsia during that pregnancy the more DNA is transferred?), so check out Google Scholar or another academic search engine if you want to know more about this new and exciting area of research (or start with this useful review article).
Two other pieces of info the NIPT can give you
When you’re looking at chromosomes, you can get lots of info, not just details on whether a baby has a typical chromosomal setup.
The NIPT can tell you the sex of the baby. We know our baby is a girl because the DNA indicated XX sex chromosomes. The test can also tell you if a baby is XY, X, XXY, XXX, or XYY. Being XX (female) or XY (male) are the two typical outcomes.
This has been the case for a while. When I was pregnant five years ago, we found out Eleanor was a girl because of the NIPT.
But, there’s a NEW piece of information that the NIPT can tell us now that it couldn’t tell us five years ago — part of the baby’s blood type. 😮
That’s right! We can now know from NIPT results whether a baby has a positive or negative blood type (has the Rh protein or doesn’t have the Rh protein).
This is so cool! And, here’s why it’s also changing a key piece of pregnancy care.
When someone who is Rh negative gets pregnant, providers will usually try to figure out if their partner is Rh positive. That’s because if someone is Rh negative, their immune system may try to attack any blood cells that are Rh positive (this doesn’t happen in reverse — Rh positive people don’t find their immune systems attacking Rh negative blood cells). And sometimes, baby’s blood cells get into mom’s blood stream. (This is not the same as baby’s DNA getting into mom’s blood stream; this is rarer, and potentially more harmful if an Rh- mom’s immune system starts attacking an Rh+ baby’s blood cells.)
Rh proteins are genetic, but not in a simple or straightforward way. Basically, even if your parents are both Rh+ or Rh-, you could be the opposite.
An issue can arise when mom is Rh- and is pregnant with an Rh+ baby; what if some of the baby’s blood crosses into mom’s blood stream and triggers an immune response? Or, what if that mom gets pregnant again and the body attacks the new baby because it’s learned to attack Rh+ cells?
So, if mom is Rh-, most providers want to make sure that mom’s immune system gets some antibodies to teach it NOT to attack Rh+ blood. This happens through a shot (editorializing here: a highly uncomfortable shot) around 28 weeks gestation for a typical, healthy pregnancy. If someone is experiencing spotting or bleeding earlier in pregnancy, this shot may happen earlier and/or multiple times. (This shot, in case you want to learn more about it, is called the RhoGAM. Here is a long explanation of the science behind it.).
Back to the NIPT.
The NIPT can now report whether a baby has Rh+ or Rh- blood.
That’s really amazing, from just a knowledge point of view. And, this is relatively new; I contacted Natera, the company that administered my NIPT both five years ago and a few weeks ago, to find out when they added the Rh factor to their tests — it was in May 2024! But, the article that provides proof of concept for this as an intervention is slated to come out in February 2025!
In addition to being amazing information, this is also actionable. From a healthcare point of view, that means we don’t have to give RhoGAM shots to every Rh- pregnant person; we can just give those shots to the Rh- pregnant moms with known Rh+ babies. Fewer unnecessary injections!
(I’m going to highlight here that RhoGAM is a potentially life-saving intervention for Rh- moms with Rh+ babies. The evidence is clearly on the side of RhoGAM for people who may need it.)
Anyway, the NIPT can tell you (if your provider requests it), whether your baby is Rh- or Rh+. It can tell you the baby’s sex. And, it can tell you if your baby is more or less likely to have a number of genetic conditions that may be useful to know about.
I’m so grateful for the science that helps us care better for families, and that helps me know what I want to know as we prepare to welcome Baby Jorgensen.
Abby the Sociologist Doula 