Low Papp-a: what is this and what does it mean for me?
Okay! So I’ve decided to write a blog post on low PAPP-A levels because its come up recently and it is a tricky one to find information and details about this. I think if you are someone who gets told that you have got this, it can definitely send you into a bit of a panic - simply because its an unknown and you don’t know what this means for you! The risks can sound terrifying so its important to know what they are and understand them a bit better.
To help ladies experiencing this get the correct information (and resources) to make an informed decision, and also just to get some reassurance, I have tried to compile some of the useful information that I have found in one place to give some accurate understanding to what it is and what it means.
So, firstly, what is PAPP-A?
PAPP-A stands for Pregnancy-Associated Plasma Protein-A. It is a hormone - placenta produced protein. During the 12 week scan, screening tests for Downs syndrome, Edwards syndrome and Patels syndrome are offered. If you accept this screen, the fluid on the back of the babies neck is measured and a blood test is taken that has 4 markers which are being looked at. This is to define if you have a low risk of one of the said syndrome, or a high risk. One of those four markers in the blood test is the PAPP-A. This is not being looked for in isolation at the screening tests but can be discovered when looking. Having a low PAPP-A alone is not linked to any of the said syndromes.
You would be deemed as having a low PAPP-A if this hormone show levels a less than 0.4 MoM in blood during your 12 week screening tests of pregnancy.
What do we know about low PAPP-A?
What we know about low PAPP-A is that it is identified within about 5% of all pregnancies. This means that potentially the placenta is going to have to work harder and can have these possible outcomes on the placenta during pregnancy:
Placental vascularisation: reduced capillary diameters and a lower number of capillary vessels.
Placental thickness: thicker placentas.
Abnormal placental morphology: this means that the placenta may be misshaped or formed.
What are the risks of having low PAPP-A?
There is a few risks that are associated with having a low PAPP-A, and these are:
Pre-eclampsia: high blood pressure and protein in the urine.
Low birth weight.
Early or pre-term birth: baby being born before they are 37 weeks which is currently deemed full term.
Miscarriage/still birth: these is an increase risk of miscarriage in the second half of pregnancy.
Growth restriction: smaller baby than normal.
Statics for above risks:
Pre-eclampsia.
There has been a higher association of pre-eclampsia in mums with low PAPP-A than in mums whose PAPP-A levels have been above the 5th percentile.
A study looking at 102 pregnant mums with low PAPP-A between 2017 and 2019 found that there was a 9% chance of having this, compared to 3% of those without low PAPP-A.
A study retrospectively reviewing 300 women with low PAPP-A between 2013 and 2015 found that there was a 28.3% chance of pregnancy induced hypertension (high blood pressure).
Read more on this here: https://fetalmedicine.org/abstracts/2016/var/pdf/abstracts/01254.pdf
Stillbirth/miscarriage in the second half of pregnancy.
Whilst there has been a link found between low PAPP-A levels and stillbirth - the risk for this does still remain low. There is two studies here I want to share with you.
The first one is a prospectus cohort study of 7934 women between 1998 and 2000. Of the 7934 women 400 were found to have low PAPP-A levels within the first 10 weeks of gestation. Of these 400 women, 8 had stillbirths.
Read more on this study here: https://www.researchgate.net/publication/51367447_First_Trimester_Placentation_and_Risk_of_Antepartum_Stillbirth#pf4
The second study looked retrospectively at 102 cases between 2017 and 2019 - all of which were found to have low PAPP-A. They found a 2% rate of spontaneous miscarriage.
Read more on this study here: https://www.library.wmuh.nhs.uk/wp/library/wp-content/uploads/sites/2/2024/03/LOW-PAPP-A-and-Induction-of-Labour-at-40-Weeks.pdf BJOG: An International Journal of Obstetrics and Gynaecology. Conference: Royal College of Obstretriscians and Gynaecologists World Congress, RCOG 2021. Virtual. 128(SUPPL 2) (pp 159-160); Blackwell Publishing Ltd.
Growth restrictions and pre-term birth.
There has been an increased chance of small babies for gestational age (SGA) in mums with low PAPP-A.
One study of 300 mums with low PAPP-A between 2013 and 2015 found a higher chance of small babies with 27% of babies born below the 10th centile. The incidence of preterm birth was higher in the group of babies classified as SGA (33.8%) versus 7.9% in the non-SGA group.
Read more here: https://fetalmedicine.org/abstracts/2016/var/pdf/abstracts/01254.pdf
Of the 102 babies in 2017 to 2019 retrospectively reviewed, 10% were deemed to be SGA. A further 15% more were SGA when smoking or BMI were taken into the mix alongside low PAPP-A. 8% of the 102 women experienced preterm labour.
Read more on this study here: https://www.library.wmuh.nhs.uk/wp/library/wp-content/uploads/sites/2/2024/03/LOW-PAPP-A-and-Induction-of-Labour-at-40-Weeks.pdf BJOG: An International Journal of Obstetrics and Gynaecology. Conference: Royal College of Obstretriscians and Gynaecologists World Congress, RCOG 2021. Virtual. 128(SUPPL 2) (pp 159-160); Blackwell Publishing Ltd.
What does this mean for me?
So, whilst these risks have been identified within those with low PAPP-A, there is no clear understanding on why. Does the low PAPP-A cause these risk factors or is the low PAPP-A a consequence of something not being right to start with and the risk factor was destined to occur.
There is limited intervention and medicine available that can prevent the potential risks from occurring. Your NHS provider might advise you to take a dose of aspirin from week 12 of pregnancy through to week 36. The rational for this is because it is felt that it helps the blood flow easier and therefore prevent smaller babies and can reduce the risk of pre-eclampsia. Whether you want to take this or not, as always in your maternity care, is your choice. You can do your own research into this, looking at the pros and cons to be able to make an informed decision.
It is likely that you will be offered extra monitoring during your pregnancy, and these tend to start after the second half of your pregnancy. These are to monitor the growth of your baby. Despite how these might be sold to you, they are optional and totally your choice. You might be quite happy to see little one a few extra times before meeting them!
What if I am advised to have an induction?
As it stands there is not clear guidance on whether or not induction of labour should be offered at full term. Depending on where you live and your local services, their guidelines may suggest different things.
This is shown here:
This Walsall Healthcare information leaflet recommends that due to ‘risks’ of low PAPP-A that induction of labour be offered at around 40 weeks gestation.
Read this here: https://www.walsallhealthcare.nhs.uk/wp-content/uploads/2024/10/Low-PAPP-A-Information-English.pdf
And yet, in this Royal Berkshire Health care information leaflet, the opposite is advised, and it is said that having a low PAPP-A result by itself is not reason for induction.
Read this here: https://www.royalberkshire.nhs.uk/media/dvxh4mvx/low-papp-a-results-and-extra-scans_aug23.pdf
As it stand, there is no current evidence to suggest that induction of labour improves any of the outcomes. In fact, one study found that it had minimal difference in the outcome of pregnancy. This study clearly states that when low PAPP-A is in isolation the only ‘risk’ of pregnancy, that induction of labour should not be advised.
Read more on this study here: https://www.library.wmuh.nhs.uk/wp/library/wp-content/uploads/sites/2/2024/03/LOW-PAPP-A-and-Induction-of-Labour-at-40-Weeks.pdf BJOG: An International Journal of Obstetrics and Gynaecology. Conference: Royal College of Obstretriscians and Gynaecologists World Congress, RCOG 2021. Virtual. 128(SUPPL 2) (pp 159-160); Blackwell Publishing Ltd.
Do I need to accept the advice of my NHS maternity care providers?
When it comes to being offered an induction, it is very important that you look at the pros and cons to your individual situation. Do you just have a low PAPP-A result in isolation? Do you have other complications of pregnancy? Has there been a medical worry raised?
When being offered any intervention or treatment during your pregnancy and maternity care - please remember this - it is always your decision to what you do and don’t accept. Do your research. Understand the absolute risk rather than the generic ones. It is okay to ask lots of questions and to see the evidence that underpins the recommendations of care you are being offered.
As part of my Hypnobrithing course, we look in detail about decision making tools, the main one being something called the BRAIN skill. Check out my available Hypnobirthing Courses.
Resources
A great resource for low PAPP-A is this live Instagram video led by Doula Samantha Gadsden and you can watch that here: https://www.instagram.com/reel/DBCWr4ANphn/?igsh=ZXI3eXpvYXBhanJt
Some other great resources and research articles:
https://thebirthuprising.com/decoding-low-papp-a-results-in-pregnancy-what-you-need-to-know/ - this is a great article and helps prompt some questions that you might want to ask your care professionals when speaking to them about low PAPP-A levels.
https://pmc.ncbi.nlm.nih.gov/articles/PMC9731607/#sec5
https://www.thegreenmidwife.co.uk/blog/low-pappa-in-pregnancy
https://www.royalfree.nhs.uk/patients-and-visitors/patient-information-leaflets/low-pregnancy-associated-plasma-protein-papp#:~:text=babies%20and%20mothers.-,What%20is%20a%20PAPP%2DA?,%2C%20known%20as%20pre%2Declampsia.