Low PAPP-A and Celiac Disease in Pregnancy
Wednesday, November 26, 2008
Kenneth F. Trofatter, Jr., MD, PhD
Kate said...
Dear Dr.T,
I have been following your site and articles ever since my NT (nuchal translucency - combined first trimester screening) and your information, insight and attentive responses to your readers have been exemplary. Thank you SO much for writing and responding to all of us! I am 36 years old with my first baby and currently 16w3d. No history of smoking or drinking. At my NT everything looked good: my Down’s risk was 1:800 and trisomy 18/13 1:7000. I did not need to do an amnio. However my PAPP-A was .44MOM (10th percentile). I also have "suspected" Celiac disease which I will be retested for later.
I have been concerned with this low PAPP-A and when I asked my OB she was not very helpful. So in reading you articles I have gained insight but have further questions:
1) The report said my .44MOM was at 10th percentile...yet I saw many other readers with .4 etc. and were considered 5th percentile (which is a percentile cited as of concern)...am I marginally at 10th percentile and is there a big difference? Should I be concerned?
2) Is there correlation with celiac disease and placental health or low PAPP-A levels? I have read reports of celiac disease causing many of same risk factors associated with low PAPP-A.
3) The other day, I felt a gush of fluid and went to the OB where she tested me for amniotic fluid. She only did a Nitrazine and "thought" all was fine. I revisited PAPP-A levels and their correlation with PROM (premature rupture of membranes)...do you have any insight or advice on this? As a first time mom, I don't even know what a gush of amniotic at 16 weeks might feel like. But moreover...I am concerned about PAPP-A, celiac disease , and PROM.
Many thanks Dr. T!
To Kate:
Let me briefly answer the first and third questions before spending more time with the second in another post. Multiples of the median (MoM) are a measure of how far an individual test result deviates from the median. The ‘median’ is the middle of a distribution: half the scores are above the median and half are below the median. It is less sensitive to extreme values than the mean and this makes it a better measure than the mean for highly skewed distributions. The median is found by arranging all the observations from lowest value to highest value and picking the middle one. MoM is commonly used to report the results of medical screening tests, as is done with the concentrations of the maternal serum markers in both first and second trimester screening tests during pregnancy, where the median is highly variable and dependent on the gestational age. This allows comparison between laboratories and helps to ‘standardize’ interpretation of tests for sake of comparison that may be performed differently in different laboratories. In your case, the MoM for your PAPP-A value at 16 3/7 weeks is 0.44. This is less than half the median for that gestational age and places you between the 5th and the 10th percentiles, but this is not what we consider to be extremely low as would be the case at the 1st percentile. In your case, I would not see that as cause for panic!
All that said and done, as we have discussed in previous posts, the further the PAPP-A is below the median, the greater the risk is for certain pregnancy-related complications such as intrauterine growth restriction, premature labor, unexplained fetal demise, pregnancy-induced hypertensive disorders, and cesarean delivery. However, on an individual basis, the absolute risk is difficult to predict and some women with extremely low PAPP-A values have none of these complications. In the case of preterm delivery, a recent article by Spencer and colleagues (Ultrasound Obstet Gynecol 2008;31:147-52) concluded that women with PAPP-A levels in the range of yours had about twice the risk of delivery before 37 and 34 weeks.
You do raise an interesting question though and that is related to the risk of premature rupture of membranes (PROM) and low PAPP-A. I had not heard, or even thought, about that association before you raised the question. Certainly, premature labor and delivery in general is often preceded by PROM, but in the case premature delivery in association with a low PAPP-A, we tend to think more in terms of this being necessitated by fetal and/or maternal complications. Interestingly, I did find and article by She and colleagues (Taiwan J Obstet Gynecol. 2007:46:242-7) that reported that low maternal serum levels of pregnancy-associated plasma protein-A during the first trimester are associated with subsequent preterm delivery with preterm premature rupture of membranes and the authors concluded that this may be the result of “a trophoblast invasion defect in the maternal-fetal interface” which sets up the series of events leading to both PROM and preterm labor.
So Kate, thanks for the great questions and we will continue with your concerns related to celiac disease and pregnancy in our next post. And, to all our readers, have a very HAPPY THANKSGIVING!
Labels: celiac disease, PAPP-A
2 Comments:
At Thu Nov 27, 11:44:00 PM 2008,
Anonymous said…
Hi. I am 33 years old, I will be almost 34 when I give birth. I will be 22 weeks on Monday. With my 1rst trimester results I had a 1 in 7,000 chance of having a child with Downs. Both my 12 week sand 20 week ultrasounds were normal. But with my quad screening I have a 1 in 290 chance of having an baby with Downs, I wish my doctor would have informed me of these results earlier, but because the quad results weren't positive, she didn't feel the need. I was VERY concerned with a number like 1 out of 290. My doctor saw I was nervous and suggested I have an amnio. I know it's late, but I am very concerned with both alternatives: having a baby with Downs and miscarrying a healthy baby.
Is the number 1 out of 290 high for my age?
Is it worth having an amnio to alleviate my worry?
I obviously have to make a decision right away.
Thank you for your thoughts,
Cammy
At Mon May 11, 10:50:00 PM 2009,
Anonymous said…
Hi Dr T,
I don't know if you are still answering queries on this site, but I hope so. I am 28yo and currently 15wks pregnant. It's my first pregnancy. I belatedly got the detailed results of my Nuchal Translucency and Blood tests and was shocked to find that my odds of having a baby with Trisomy 21 are 1:584. I realise that this result is usually assessed as 'low risk' but I want to know why my chances are worse than other people my age (I was expecting at least 1:1000)
The details are:
12wk1d
CRL 57.8mm
NT 2.0mm
free Beta HCG - 1.3400 MoM
PAPP-A - 0.5000 MoM
All I can see is that perhaps my PAPP-A results are a bit low?
I have been sick with worry since I have gotten these results and am considering having an amnio but frightened by the risks. What is your opinion?
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