Recently I was at a lovely homebirth. Baby was born into his parents arms after a short but intense labour. No problems during the labour where identified. Once the woman and her baby were snuggled together and comfortable, I set to the task of checking the placenta under the women’s watchful glaze. Quickly we both saw that there was a true knot of the umbilical cord. I have seen quite a few true knots of the umbilical cord over the years – all of which have been identified after the birth and none of which were associated with a significant adverse outcome. I was interested in this finding as a variation on normal but the woman was reasonably concerned and wanted to know what were the implications for her baby in having a true knot of the umbilical cord?
I sat there and thought about the answer I would give. Certainly I was aware that a true knot of the umbilical cord can cause the baby stress in labour and in the worst case scenario can cause the death of a baby. But my experiences haven’t yielded any poor outcomes so I wondered how significant is it? We discussed my positive experiences and my understanding that it is associated with poor outcomes in the literature. We also talked about the fact that I didn’t know the rates of poor outcomes, so I promised to do a bit of research for the woman. Following is a summary of the information I found.
Problems with the baby’s umbilical cord can cause abnormalities of the baby’s heart rate in labour (both major and minor) and can be a cause of the baby dying before birth (Kaplan, 1996). However the umbilical cord contains special substance called Wharton's jelly and this protects the blood vessels of the cord even if a true knot occurs. The protective function of Wharton’s jelly will, most of the time, prevent a tight knot from forming, and stops the knot from interfering with the circulation of blood going to the baby. It is not common that a significant problem occurs, which is congruent with what I have noticed in my own midwifery practice.
Knots rarely tighten before labour but can do so when the baby starts descending down the birth canal. While significant problems are rare, they can occur. Where a baby has a true knot in their cord there is a definite increase in the risk of death before labour begins in comparison with babies who do not have a knot in their cord. During labour there are an increase in the number of babies who show worrying heart rate changes and those babies that pass meconium liquor (this is where the baby does a poo in the waters before birth). There is also a four-fold increase in the number of babies who die before birth. Because of complications these babies are more likely to be born by caesarean than a baby that doesn’t have a knot in their cord.
The literature indicates that a true knot of the umbilical cord occurs in between 0.3 to 2.2 percent of all births. The most commonly quoted statistic I found was 1.25 percent. Most true knots are discovered after the birth but with new ultrasound techniques some are discovered during the pregnancy. The following circumstances increase the chance of a true knot forming:
True knots of the umbilical cord are formed when the baby moves through a loop or loops of cord while being active in the uterus, and most form very early in the pregnancy (Heifetz, 1996; Hershkovitz et al., 2001; Ramón Y Cajal & Martínez, 2004; Semchyshyn, 1973). It is important to note that babies who suffer temporary stress during labour as a result of a true not usually recover shortly after birth. A true knot is not an automatic reason to plan a caesarean birth (Airas & Heinonen, 2002). In doing my research I didn’t find very many research articles on true knot of the umbilical cord – so some of this information may be the opinion of health professionals rather than fact. More research and understanding is needed.
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Written 13 March 2014 for www.pregnancy.com.au as part of the ‘Musings of a Midwife’ series.
Airas, U., & Heinonen, S. (2002). Clinical significance of true umbilical knots: A population-based analysis. American Journal of Perinatology, 19(3), 127–132.
Heifetz, S. a. (1996). The umbilical cord: obstetrically important lesions. Clinical Obstetrics and Gynecology, 39(3), 571–587. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/8862884
Hershkovitz, R., Silberstein, T., Sheiner, E., Shoham-Vardi, I., Holcberg, G., Katz, M., & Mazor, M. (2001). Risk factors associated with true knots of the umbilical cord. Eur J Obstet Gynecol Reprod Biol, 98(1), 36–39.
Kaplan, C. G. (1996). Postpartum examination of the placenta. Clinical Obstetrics and Gynecology, 39(3), 535–548. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/8862882
Ramón Y Cajal, C. L., & Martínez, R. O. (2004). Prenatal diagnosis of true knot of the umbilical cord. Ultrasound in Obstetrics and Gynecology, 23(1), 99–100. doi:10.1002/uog.900
Semchyshyn, S. (1973). True knot of the umbilical cord in two consecutive pregnancies. CMA Journal, 6, 1973.
17 comment(s) on this page. Add your own comment below.
Hi Sarah - I am very sorry for the loss of your baby boy. I hope this article helped a little with your knowledge of true knots.
I had twins 35 years ago and didn't know I was having them until on the delivery table....The first one was small 5 lbs. 3 oz. but the second was larger 6lbs. 5 oz. and forceps had to be used...The doctor kept saying there was one placenta but they are not identical...No problem with knots to my knowledge, but your article was "very interesting"...
My baby girl died at 38 1/2 weeks due to a true tight knot. Up until her death, her scores were perfect. I lie here now, unable to sleep cuz I miss my Zailee .
My middle son was a home birth and was born with the cord around his neck and also had a very tight true knot in his cord. You know when you have a shoelace and it has such a tight knot in it can't be undone? It was like that. The midwives said I was incredibly lucky that he was born alive and well and It must've happened when he was tiny as he didn't have a very long cord at all. He is seven now and mostly well, however he does have some mild to moderate difficulty with the physical act of writing and drawing and also difficulties with telling his left from his right as well as other coordination difficulties. Although we cannot know for sure the tight cord knot was a contributing factor it seems a strong possibility. We got off very mildly though. It was never picked up on ultrasound and I never noticed any decrease in foetal movements.
My first child was also born with a true knot in his cord. I knew something wasn't quite right as I'd had to attend the hospital several times due to decreased movement. The cause was never investigated, I was never even offered a scan, and after a traumatic birth were his heart rate dropped and he had to be born via emergency ventouse delivery we discovered a knot in his cord. I am so grateful that nothing terrible happened to the baby and I firmly believe more needs to be known about true knots. Thank you for your article.
We lost our beautiful sweet baby boy Jaxon at 36 weeks 2days. Dr. Jason Collin wrote a book on umbilical cord accidents. There where so many red flags with my son. Should be taken very serous if red flags come up. The pain is unbearable I miss my son and still have not held a baby since I lost him
We lost our baby at 33 weeks to a true knot. We had a scan the day before as the baby was restless, I have even found out since that this was a doppler scan, which shows blood flow. And the knot was still not detected. She died the next day.
My daughter Taia was born 2 weeks late at 9lb 10.5oz with a true knot in her cord. I didn't understand the implications of this until I had quite a few visits from trainees and doctors explaining what had happened. She was very floppy after birth and suffered with benign hypotonia in her early years. I've no idea if this is a characteristic of true knot or oxygen reduction. I am very grateful to have her with us and i'm so sad for others of you that have lost your little ones. Taia turns 13 in february and I still find the need to process what happened occasionally.
My Baby Boy was born last Wednesday by an Emergency C-section, having been left for too long when my waters had broken and then being induced, which lead to me developing an infection. However I was told that my labour might have been very difficult anyway and ended up with a C-section as my little boy had a true knot I his cord as well.
We just lost our baby girl today. My wife was scheduled for an induction today and during the day yesterday and into the night my wife was having contractions but the times were all over the place. Well late last night she had not felt any movement from the baby and contractions were gone. We went straight to the hospital with positive thoughts and when they could not find the heartbeat it was crushing. When she delivered we found out it was because of a tight knot in the cord. we are heartbroken that we have lost our little Sadie Bea. Along with the pain we are feeling it was so hard to tell our other 5 children. It's just horrible.
I was 40 weeks and my blood pressure was slightly raised. My doc induced by at about 7 or 8 cm after almost 10 hrs of labour the baby went into distress. She recovered but the doc was not convinced. She was born with a true know. . It was very tight. I'm very happy that the events to get birth led to a csection and she survived with no after effects. I don't wavy to think about what could have happened. We were blessed.
Our daughter lost her beautiful baby girl 16 days before her due date. She had a healthy pregnancy with no complications but her baby died due to a cord accident. Why was there no sign of a problem six days before this tragedy when she had an ultrasound and her scores were perfect?
My grandson was born on 26 January 2015 by emergency C-section after a long labour , baby not descending, etc. When born they discovered 5 knots in one in his umbilical chord. But praise God, he is fine! My heart goes out to everyone who had lost their precious babies.
To Kevin and those that lost their babies I true knots... I am so sorry to read about your losses. It is absolutely devastating. I am 24 years old, and I was a true knot baby. The doctor said she had only seen a true knot twice in her career, and the other had baby passed away. My mother had to undergo an emergency c-section and I was fortunate to make it without any further complications. I am deeply saddened to read that so many babies do not make it. My heart goes out to all of you. :(
Baby david was born 3 days ago at 41 weeks with a true knot. Decreased movements had led us to hostpital trips in previous weeks. Within the first 5 mins of being at the hospital and the baby being monitored his heart beat stopped for 2 minutes. I was rushed for samples to be taken from Davids head but the tests showed no abnormality. 3 hours into the labour the same thing happened again, a large contraction followed by his heart beat not recovering. This determined my C section to start immediately. Upon giving birth I was shown the placenta and a very tight true Knott. I was experiencing lots of decreased movements after week 38 and am glad that I insisted on arriving at the hospital on my birth day earlier than the staff wanted me to be there (waters had not broke yet) and was advised to wait). The doctors were very surprised at how much fluid I was carrying in my waters, and had to break my waters 3 times during labour. I am so sorry for everyone who has lost loved ones, my heart goes out to you. Thank you Jane for the study.