What is IUGR?

November 10, 2014
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by Lindsey Wimmer, RN, MSN, CPNP, CPLC

Intrauterine Growth Restriction (IUGR) is receiving a lot of attention recently as it relates to perinatal loss. I am very encouraged by this and the promising studies that are being done.  A recent video has been circulating through social media that highlights the issue (Born Asleep: part 1, part 2, part 3).

I’ve been getting many questions from parents about what IUGR actually IS.  I think it’s a very important question.

The most important thing we need to understand about IUGR is that is it a symptom, not a diagnosis.  

Providers will often provide this as a diagnosis if there is a poor outcome in a pregnancy or even identify it as a cause of death.  Being small does not, in itself, post a lethal problem.  But WHY a baby is small very well could be a serious problem.

Studies have indicated that more than half of all stillborn babies are growth restricted. This tells me that these babies had issues going on through the pregnancy that were limiting the baby’s ability to develop and grow appropriately – and, ultimately to survive.

Growth restriction, by definition, requires us to recognize that a baby’s growth pattern is not following expected norms.  In pediatrics, we do this with every single well-child visit from birth to adulthood.  If a child is at the 75th percentile for his/her age and is consistently at that mark, we consider that appropriate growth.  However, if a child is usually at the 75th percentile and is suddenly down to the 25th percentile – we are going to be investigating because that is a significant change.  Growth charts can be utilized for fetal growth in the same way – and usually are when IUGR is suspected and identified during a pregnancy.  The problem is when a diagnosis of IUGR is made from a single assessment.  From a single point in time, it is not feasible to identify if a baby measuring at the 25th percentile is acceptable or not.  It depends on what the baby has done in the past, but we often don’t have that information.

Most providers and facilities have identified trigger points at the 10th percentile or 5th percentile.  If a baby is under those marks, they may be diagnosed with IUGR.  This can be problematic because it may mean that we are concerned about a baby that is naturally a smaller person OR it may be that we don’t catch a baby that is very sick until it progresses to this extreme.  It is more appropriate to consider a baby “appropriate for gestational age” (AGA), “small for gestational age” (SGA) or “large for gestational age” (LGA) rather than IUGR if we are only looking at data from one assessment  These terms simply describe the child’s size without indicating if it is a concern or not.  However, it is important to remember that any of these babies could ALSO be growth restricted – but we need more information to know.  Once a baby is born, if we identify growth restriction (known as ‘failure to thrive’ in the pediatric setting), we will begin looking into potential causes.  We look at the sources of the baby’s nutrition, the baby’s anatomy and physical health, the baby’s behaviors and patterns, the baby’s environment, and more.  The baby’s size is considered a symptom – not a final diagnosis.  We may not be able to directly affect the baby’s growth, but we can address the underlying cause (in most cases) and indirectly improve growth.  The growth pattern is simply another vital sign that indicates how well the baby is doing.

This isn’t always the approach to baby’s growth (or restricted growth) in obstetrics.  Any baby diagnosed with IUGR should be having serial ultrasound measurements and further testing to identify the cause of the limited growth and the baby’s tolerance of the issues.  Examples could include placental concerns, restricted blood flow through the umbilical cord, infection, or genetic or anatomical abnormalities. This information gives the obstetrical providers information about how to manage the pregnancy moving forward.

Probably my biggest frustration with IUGR is that in ‘healthy’ pregnancies, it is only looked for by measuring fundal height (the tape measure of mom’s ‘bump’). This method has been noted in literature to be faulty and neither sensitive or specific.  But it continues to be the standard of care because it is easy and inexpensive.  I am very concerned, however, that this practice keeps us from identifying babies that are struggling under our radar and we lost a chance to intervene and help them survive and thrive. The technology exists for ultrasound measurements to be taken regularly throughout the pregnancy to better assess baby’s growth.

Many stillbirth families are told that their baby died of IUGR, yet they did not have any idea this was a concern before the baby had died.  Further, they aren’t given any information about WHY their baby had IUGR.  These are significant omissions that could have implications for parental grief, management of and health of subsequent pregnancies, or for public health stillbirth prevention efforts.



Thank you for clarifying what IUGR is. This is a well written article. I was fortunate enough to receive plenty of information from my perinatologist in regards to why my baby was not growing properly. My uterine vessels were severely restricted instead of expanded. This, coupled with preeclampsia, early onset, led to her death. She stopped progressing in growth, I was in severe preeclampsia and since our daughter was less than 300 grams at the 24th week, we induced to save my life.

IUGR is a diagnosis antenatally as well as a symptom in utero since as a Maternal-Fetal Medicine specialist, once we Diagnosis a fetus as IUGR and we then do serial assessments depending on the situation. This generally applies as either every 2 weeks assessments to as intensive as daily assessments. It is disheartening to hear that providers are stating that the baby died of IUGR which makes no sense. Obviously there is an underlying cause to the IUGR and I hope that those families have been connected with a Maternal-Fetal Medicine specialist to do the assessments that would have been appropriate.
While facilities do label pregnancies as IUGR with a single growth assessment, the follow-up will confirm or not confirm the actual diagnosis of IUGR. You are correct that one snapshot does not make a diagnosis but once the diagnosis is made, the mother is subjected to multiple ultrasounds. You allude to the possibility that serial ultrasounds are not performed. Are these ultrasounds performed by the radiology department and then these families not referred to high risk specialists?
Additionally, depending on when the growth restriction is identified, maternal nutrition is not likely a factor unless there is a famine or there is anorexia/bulemia component. Earlier the growth restriction, more likely it is a placental or genetic issue whether it may be a thrombophilia, hypertension, connective tissue disorder of the mother for example or a problem with the placenta or an intrinsic issue with the baby.
That being said, does the public understand and know that the nomograms for fetal weight and gestational age are based upon certain demographic, social economic status and ethnicity. The majority of the US population does not fall within those criteria. How would a mixed race couple from the West Coast measure versus one that is from Africa and imigrated to the US versus one from that is from the projects in NY and is dependent on Medicaid. I am not sure how the pediatric height and weight charts compare but it is virtually impossible to evaluate every child based upon race, social economic status and location.
As there are a wide variety of what is considered normal in adults and children so to fetuses. I do agree that an ultrasound assessment periodically every trimester would be helpful but that would not only benefit those families of stillbirth but also those that may diagnose those fetuses that may have another intrinsic issue whether it may be maternal or fetal.


Serena – Thank you for your comments and great explanations. You are exactly right about the variations in growth patterns based on so many factors. And that serial ultrasounds could benefit MANY types of babies and families. Unfortunately, we do hear of women who are diagnosed with abnormal fetal growth patterns without getting special followup or referral. Just as troubling to me, there are many pregnancies that may have IUGR (among many other issues) that are missed because their risk factors aren’t recognized and treated as such. As an example, a mother recently contacted me. She was told her baby was big (based on fundal height measurements only), but that was likely because of her obesity and borderline GDM. Once her baby was stillborn, they were shocked to be told the ’cause’ of the baby’s death was IUGR. Clearly, there are many opportunities for education, awareness, and improvement. 🙁

I would love to talk to you sometime about your experiences and perspectives of the issues!

Hi Lindsey,

Thank you for your comments and response. It is really unfortunate to hear that the IUGR is considered a diagnosis and that seems to be from a general OB/GYN and not a perniatologist.
I am not sure how one is borderline GDM since one is either diabetic or not. She most likely has glucose intolerance and was suspected to be at high risk though her testing was negative. Or if her testing was equivocal, that should have kicked her into a higher risk category. Unfortunately again, depending on where these women are and the resources, there may not be a perinatologist available.

I would love to discuss these issues with you at some time.
I just read your article on nuchal cords and the one in regards to kick counts from the nurse. Actually, public awareness and education should be a bigger push. You wouldn’t believe how many pregnant women say the exact same things to me as what the article stated even when I tell them to do their kick counts, that mothers know best, to not be concerned about being a nuisnace. They completely discount it.

Unfortunately, patient discount kick counts more than you think.


We lost our son 7 weeks ago. I was 28W4D when I delivered. He was only 10 1/2 inches and 13.3oz and they estimate he had been dead several days. I had been sick, which masked his momements (or lack there of). It was blamed on placental infarction. They found false knots in his chord as well, but all the pathology came back that the placenta was dying or dead in some areas. This lends to IUGR, but our OB stopped short of saying that. We are meeting with an MFM next week and I hope to get more answers we also are going to do some testing as we want to try again.

I had a normal pregnancy, at our 20 weeks can, they said he was measuring a week and a half behind and when I questioned it they said it was not an issue. They never brought it up again and even though I questioned it and felt I didn’t receive a good answer or any answer how am I supposed to question someone who does this day in and day out. I wish I had pushed more as I think he would have had a better chance. After the 20 weeks scan I had two more appointments prior to losing him. They never said anything, but I had no weight gain etc (I am overweight to begin with). How did the miss this? I really feel like they dropped the ball.

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