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Standards for measuring umbilical cord length
Placenta (I983), 4, 423-426
Standards for Measuring Umbilical Cord Length JAMES L. M I L L S a,c, E R N E S T E. H A R L E Y a & A D R I E N C. M O E S S I N G E R b a Epidemiology and Biometry Research Program, NationalInstitute of Child Health and Human Development, National Institutes of Health, Landow Building, Bethesda, MD 2o2o5, USA b Department of Pediatrics, College of Physicians and Surgeons, Columbia University, USA To whom correspondence should be addressed
INTRODUCTION Fetal growth standards have classically included the measurements of body weight, body length and head circumference. These measurements are an integral part of the physical examination of any newborn infant since a deviation from the norm suggests selective pathological processes. Until recently the factors controlling umbilical cord length were poorly understood and its measurement, once a time-honoured ritual, has been abandoned in most obstetrical services. It now appears that cord length at birth might represent an index of fetal activity, given adequate space for movement (Miller, Higginbottom and Smith, i98i; Moessinger et al, 1982). In addition, extremes in cord length have been associated with fetal heart rate abnormalities and fetal distress (Bain and Eliot, 1976; Rayburn, Beynen and Brinkman, 198 i). In light of these new findings, a standard curve for umbilical cord length is needed to identify deviations from the norm.
METHODS Data on cord length were gathered as part of the Collaborative Perinatal Project-NINDB. Participants came from I3 hospitals covering a wide geographical area. Details of patient selection have been described elsewhere (The Collaborative Study, x966). Gestational age was determined by the woman's report of her last menstrual period and the actual date of confinement. Umbilical cord measurements were available on 962o of 12 688 (76 per cent) white male and 9o68 of i 1 932 (76 per cent) white female infants born in the study. Umbilical cords were measured with a metric ruler in the delivery room. The segments attached to the baby and the placenta were measured and the results added. If any part of the cord had been cut out, this was also measured and added to give total cord length. Data from all births occurring after I9 weeks' gestation were examined. The growth curve was constructed for cases of 34 to 43.5 weeks' gestation. The number of cases born before or after this period was small enough (fewer than ioo per week) to raise concern that errors in calculating gestational age would distort the growth curve. 423
424
J. L. Mills, E. E. Harley, A. C. Moessinger
Growth curves were plotted from data on umbilical cord lengths in 5 cm intervals and gestational age in weeks. Curves were constructed for the 3rd, ioth, 25th, 5oth, 75th, 9oth and 97th percentiles. Smoothing was performed on the first and last observations by doubling the observation, adding the next observation to it and dividing the result by three. All other observations were doubled, added to the preceding and following observations and divided by four.
RESULTS The results are shown for white males (Figure i) and females (Figure 2). Males have significantly longer umbilical cords, on the average, than females (P < o.ooo i). Umbilical cords grow from a mean of 53.75 cm (51.75 cm in females) at 34 weeks to 6o.25 cm (57 cm in females) at term. After 4~ weeks there is little additional growth. There is great variability in cord length; at the same gestational age the longest cords are more than twice the length of the shortest. White
Males
r
90
/
r_
"~
97tti
1,,-
90th
~ - ~ " ~ --
75tH
|
-~
70
~ Z
60
~ .,.,..,.~'-~ " " " ' - ' ~
50th
UJ .-I cr
0
"
50
40
~ ~'
~-"
25th
~
30
20
34
36
38
40
42
44
WEEKS GESTATION
Figure i. Umbilicalcord length by gestationalage in US white males.
DISCUSSION The distribution of the umbilical cord lengths at term shows a good correspondence with recently published series (Walker and Pye, I96o; Malpas, I964; Purola, 1968; Rayburn, Beynen and Brinkman, 198 i). These studies are, however, inadequate to provide umbilical cord growth
Umbilical Cord Length Standards
~5
White Females
r
90
I
_.._t'80
~
~ L ~ ....- ~VgOth
"--
75th t
z
----" ~
500"
o o
o
50
_.~ f _ ~
30
20
25t1" ~
lOtt"
~-
34
36
38
40
42
44
WEEKS GESTATION
Figure
2. Umbilical cord length by gestational age in US white females.
standards since, combined, they include fewer than 3000 measurements from different countries, and represent a sample of mixed races. Moreover, fewer than 6o measurements are from gestations of 37 weeks or less. Our study is large enough to provide standards for umbilical cord length in the US white population for gestational ages between 34 and 43.5 weeks. As noted by Walker and Pye (196o) males have longer cords than females. This is not surprising since males are heavier and longer than females at birth. Alternatively, the difference in cord length could be the result of varying degrees of fetal activity. In contrast to two recent studies (Walker and Pye, I96O; Malpas, 1964), but in accordance with an earlier one (Fog, 193o), our results demonstrate that the umbilical cord continues to grow throughout the third trimester. It is, therefore, important to take both sex and gestational age into account when evaluating cord length. The concept that tensile forces exerted on the cord by fetal movements are important determinants of cord length is supported by both experiments on animals and 'experiments of nature' in human fetuses (Miller, Higginbottom and Smith, 198 i; Moessinger et al, 1982). Short cords have been associated with conditions resulting in impaired fetal mobility such as the amniotic band syndrome, oligohydramnios of varied aetiologies or duration, maternal uterine malformation, and some congenital neuromuscular diseases (Miller, Higginbottom and Smith, 1981). It has also been postulated that unusually short or long cords are related to intrapartum fetal heart rate abnormalities and fetal distress (Bain and Eliot, 1976; Rayburn, Beynen and Brinkman, i98i ). In summary, this study has used measurements on a large sample of the US white population to construct standards for umbilical cord growth late in pregnancy. These standards will
426
j . L. Mills, E. E. Harley, A. C. Moessinger
facilitate identification of significant deviations from the norm. Identifying abnormally short or long cords may help the obstetrician explain intrapartum complications as well as alerting the paediatrician to associated developmental anomalies.
SUMMARY Umbilical cord length was measured in 962o male and 9o68 female infants and related to gestational age in order to construct a growth chart for umbilical cords. In addition to providing a standard for the US white population, these growth charts illustrate that umbilical cord length is widely divergent at the same gestational age, males have longer cords than females (P < o.oooI), and umbilical cord growth continues throughout the third trimester.
ACKNOWLEDGEMENTS We appreciate Mr Robert Nugent and Ms Marcia Withiam's assistance in analysing these data, Dr William Blanc's helpful suggestions and Ms Beverly Trainor's assistance in preparing this manuscript.
REFERENCES Bain, C. & Eliot, B. W. (t 976) Fetal distress in the first stage of labour associated with early fetal heart rate decelerations and a short umbilical cord. Australian and New Zealand Journal of Obstetrics and Gynaecology, t6, 51-56. The Collaborative Study on Cerebral Palsy, Mental Retardation, and Other Neurological and Sensory Disorders of Infancy and Childhood (I966) Bethesda, MD, US Department of Health, Education and Welfare Public Health Service. Fog, J. (193o) Die Lange der Nabelschnur. Acta Obstetrica et Gynecologica Scandinavica, 9, I32-149. Malpas, P. (1964) Length of the human umbilical cord at term. British Medical Journal, i, 673-674. Moessinger, A. C., Blanc, W. A., Marone, P. A. & Polsen, D. C. (x982) Umbilical cord length as an index of fetal activity: experimental study and clinical implications. Pediatric Research, I6, lO9-1 I2. Miller, M. E., Higginbottom, M. & Smith, D. W. (1981) Short umbilical cord: its origin and relevance. Pediamcs, 67, 618-621. Purola, E. (1968) The length and insertion of the umbilical cord. Annales Chirurgiae et Gynaecologiae Fenniae, 57, 621-622. Rayburn, W. F., Beynen, A. & Brinkman, D. L. (1981) Umbilical cord length and intrapartum complications. Obstetrica Gynecologica, 57, 45o-452. Walker, C. W. & Pye, B. G. (I96O) The length of the human umbilical cord. British Medical Journal, t, 546-548.
Standards for Measuring Umbilical Cord Length JAMES L. M I L L S a,c, E R N E S T E. H A R L E Y a & A D R I E N C. M O E S S I N G E R b a Epidemiology and Biometry Research Program, NationalInstitute of Child Health and Human Development, National Institutes of Health, Landow Building, Bethesda, MD 2o2o5, USA b Department of Pediatrics, College of Physicians and Surgeons, Columbia University, USA To whom correspondence should be addressed
INTRODUCTION Fetal growth standards have classically included the measurements of body weight, body length and head circumference. These measurements are an integral part of the physical examination of any newborn infant since a deviation from the norm suggests selective pathological processes. Until recently the factors controlling umbilical cord length were poorly understood and its measurement, once a time-honoured ritual, has been abandoned in most obstetrical services. It now appears that cord length at birth might represent an index of fetal activity, given adequate space for movement (Miller, Higginbottom and Smith, i98i; Moessinger et al, 1982). In addition, extremes in cord length have been associated with fetal heart rate abnormalities and fetal distress (Bain and Eliot, 1976; Rayburn, Beynen and Brinkman, 198 i). In light of these new findings, a standard curve for umbilical cord length is needed to identify deviations from the norm.
METHODS Data on cord length were gathered as part of the Collaborative Perinatal Project-NINDB. Participants came from I3 hospitals covering a wide geographical area. Details of patient selection have been described elsewhere (The Collaborative Study, x966). Gestational age was determined by the woman's report of her last menstrual period and the actual date of confinement. Umbilical cord measurements were available on 962o of 12 688 (76 per cent) white male and 9o68 of i 1 932 (76 per cent) white female infants born in the study. Umbilical cords were measured with a metric ruler in the delivery room. The segments attached to the baby and the placenta were measured and the results added. If any part of the cord had been cut out, this was also measured and added to give total cord length. Data from all births occurring after I9 weeks' gestation were examined. The growth curve was constructed for cases of 34 to 43.5 weeks' gestation. The number of cases born before or after this period was small enough (fewer than ioo per week) to raise concern that errors in calculating gestational age would distort the growth curve. 423
424
J. L. Mills, E. E. Harley, A. C. Moessinger
Growth curves were plotted from data on umbilical cord lengths in 5 cm intervals and gestational age in weeks. Curves were constructed for the 3rd, ioth, 25th, 5oth, 75th, 9oth and 97th percentiles. Smoothing was performed on the first and last observations by doubling the observation, adding the next observation to it and dividing the result by three. All other observations were doubled, added to the preceding and following observations and divided by four.
RESULTS The results are shown for white males (Figure i) and females (Figure 2). Males have significantly longer umbilical cords, on the average, than females (P < o.ooo i). Umbilical cords grow from a mean of 53.75 cm (51.75 cm in females) at 34 weeks to 6o.25 cm (57 cm in females) at term. After 4~ weeks there is little additional growth. There is great variability in cord length; at the same gestational age the longest cords are more than twice the length of the shortest. White
Males
r
90
/
r_
"~
97tti
1,,-
90th
~ - ~ " ~ --
75tH
|
-~
70
~ Z
60
~ .,.,..,.~'-~ " " " ' - ' ~
50th
UJ .-I cr
0
"
50
40
~ ~'
~-"
25th
~
30
20
34
36
38
40
42
44
WEEKS GESTATION
Figure i. Umbilicalcord length by gestationalage in US white males.
DISCUSSION The distribution of the umbilical cord lengths at term shows a good correspondence with recently published series (Walker and Pye, I96o; Malpas, I964; Purola, 1968; Rayburn, Beynen and Brinkman, 198 i). These studies are, however, inadequate to provide umbilical cord growth
Umbilical Cord Length Standards
~5
White Females
r
90
I
_.._t'80
~
~ L ~ ....- ~VgOth
"--
75th t
z
----" ~
500"
o o
o
50
_.~ f _ ~
30
20
25t1" ~
lOtt"
~-
34
36
38
40
42
44
WEEKS GESTATION
Figure
2. Umbilical cord length by gestational age in US white females.
standards since, combined, they include fewer than 3000 measurements from different countries, and represent a sample of mixed races. Moreover, fewer than 6o measurements are from gestations of 37 weeks or less. Our study is large enough to provide standards for umbilical cord length in the US white population for gestational ages between 34 and 43.5 weeks. As noted by Walker and Pye (196o) males have longer cords than females. This is not surprising since males are heavier and longer than females at birth. Alternatively, the difference in cord length could be the result of varying degrees of fetal activity. In contrast to two recent studies (Walker and Pye, I96O; Malpas, 1964), but in accordance with an earlier one (Fog, 193o), our results demonstrate that the umbilical cord continues to grow throughout the third trimester. It is, therefore, important to take both sex and gestational age into account when evaluating cord length. The concept that tensile forces exerted on the cord by fetal movements are important determinants of cord length is supported by both experiments on animals and 'experiments of nature' in human fetuses (Miller, Higginbottom and Smith, 198 i; Moessinger et al, 1982). Short cords have been associated with conditions resulting in impaired fetal mobility such as the amniotic band syndrome, oligohydramnios of varied aetiologies or duration, maternal uterine malformation, and some congenital neuromuscular diseases (Miller, Higginbottom and Smith, 1981). It has also been postulated that unusually short or long cords are related to intrapartum fetal heart rate abnormalities and fetal distress (Bain and Eliot, 1976; Rayburn, Beynen and Brinkman, i98i ). In summary, this study has used measurements on a large sample of the US white population to construct standards for umbilical cord growth late in pregnancy. These standards will
426
j . L. Mills, E. E. Harley, A. C. Moessinger
facilitate identification of significant deviations from the norm. Identifying abnormally short or long cords may help the obstetrician explain intrapartum complications as well as alerting the paediatrician to associated developmental anomalies.
SUMMARY Umbilical cord length was measured in 962o male and 9o68 female infants and related to gestational age in order to construct a growth chart for umbilical cords. In addition to providing a standard for the US white population, these growth charts illustrate that umbilical cord length is widely divergent at the same gestational age, males have longer cords than females (P < o.oooI), and umbilical cord growth continues throughout the third trimester.
ACKNOWLEDGEMENTS We appreciate Mr Robert Nugent and Ms Marcia Withiam's assistance in analysing these data, Dr William Blanc's helpful suggestions and Ms Beverly Trainor's assistance in preparing this manuscript.
REFERENCES Bain, C. & Eliot, B. W. (t 976) Fetal distress in the first stage of labour associated with early fetal heart rate decelerations and a short umbilical cord. Australian and New Zealand Journal of Obstetrics and Gynaecology, t6, 51-56. The Collaborative Study on Cerebral Palsy, Mental Retardation, and Other Neurological and Sensory Disorders of Infancy and Childhood (I966) Bethesda, MD, US Department of Health, Education and Welfare Public Health Service. Fog, J. (193o) Die Lange der Nabelschnur. Acta Obstetrica et Gynecologica Scandinavica, 9, I32-149. Malpas, P. (1964) Length of the human umbilical cord at term. British Medical Journal, i, 673-674. Moessinger, A. C., Blanc, W. A., Marone, P. A. & Polsen, D. C. (x982) Umbilical cord length as an index of fetal activity: experimental study and clinical implications. Pediatric Research, I6, lO9-1 I2. Miller, M. E., Higginbottom, M. & Smith, D. W. (1981) Short umbilical cord: its origin and relevance. Pediamcs, 67, 618-621. Purola, E. (1968) The length and insertion of the umbilical cord. Annales Chirurgiae et Gynaecologiae Fenniae, 57, 621-622. Rayburn, W. F., Beynen, A. & Brinkman, D. L. (1981) Umbilical cord length and intrapartum complications. Obstetrica Gynecologica, 57, 45o-452. Walker, C. W. & Pye, B. G. (I96O) The length of the human umbilical cord. British Medical Journal, t, 546-548.