- Email: [email protected]
Umbilical cord length: Clinical significance
Umbilical cord length." Clinical significance Umbilical cord length in 35,779 neonates was analyzed to determine values after mid-gestation and to see if abnormal values have clinical signOqcance. Growth slowed after the twenty-eighth week of gestation but did not stop before term. Cord length had a positive correlation with maternal height, pregravid weight, pregnancy weight gain, socioeconomic status, and the fetus being male. Short cords were associated with subsequent psychomotor abnormalities, but taken alone their predictive value was low because the normal range of cord lengths is" large. Short cords were much better predictors' of subsequent impairments when they were combined with other neonatal predictors. Short cords" doubled or tripled the predictive values of low Apgar scores and several other neonatal abnormalities for subsequent low IQ values and neurologic abnormalities. (J PED/ATR 1985;107:278-281)
Richard L. Naeye, M.D. Hershey, Pennsylvania
FOR MANY YEARS physicians have recognized the mechanical consequences of an abnormally short or abnormally long umbilical cord. A length of at least 32 cm has been claimed necessary to prevent traction on the cord during vaginal delivery, so it is not surprising that shorter cords occasionally delay completion of the second stage of labor or cause placental abruptions, inversion of the uterus, cord herniation, and cord rupture. 14 Abnormally long cords increase the frequency of cord prolapse, true knots, and coiling of the cord around fetal parts, all of which can produce fetal distress through cord compression. 1-6 More recently researchers have begun to investigate what regulates cord length and to wonder if abnormal cord length might sometimes be a marker for other developmental abnormalities. 6 Miller et al. 3,4 and Moessinger et al? have published evidence that tension applied to the coi'd by fetal movements influences its length. Because central nervous system malfunction can limit fetal movements, we have attempted to determine if cord length has any prognostic value for childhood psychomotor impairments not related to easily recognized central nervous system anomalies.
From the Department of Pathology, M. S. Hershey Medical Center, The Pennsylvania State University College of Medicine. Submitted for publication Aug. 29, 1984; accepted Jan. 2, 1985. Reprint requests: Richard L. Naeye, M.D., Department of Pathology, M. S. Hershey Medical Center, Pennsylvania State University College of Medicine, Hershey, PA 17033.
278
TheJournalofPEDIATRICS
METHODS Data for the study came from 35,779 successful singleton pregnancies in the Collaborative Perinatal Study of the National institutes of Neurological and Communicative Disorders and Stroke. 7 Participants came from 13 hospitals from different areas of the United States. Details of patient selection have been previously published. 7 Umbilical cords were measured in the delivery room. The segments~ attached to the baby and the placenta were measured and the results added. Any part that had been cut out was also measured and added to give the total cord length. Gestational ages were calculated from ~he first.day of the last menstrual period. Corrections had to be made in some of these calculated ages because some mothers bled at the end of the first and second months of gestation. 8 The corrections were made by using birth weight cutoff values for each preterm gestational age to eliminate from the analyses infants who were 1 or 2 months older than the age calculated from the menstrual history. Hypertension Was considered to be present when two or more diastolic blood pressures were recorded at >--90 mm Hg during pregnancy. Alcoholism and narcotic addiction were diagnoses derived from maternal history and from observations made by the Project staff. The socioeconomic index used in the analyses combined scores for maternal education, husband's occupation, and family income. 9 Cases of abruptio placentae, umbilical cord rupture, and other recognized umbilical cord traumas were excluded so that the analyses would reflect nontraumatic correlations between cord length and psychomotor abnormalites. Cbil-
Volume 107 Number 2
dren with congenital malformations that might shorten life span were also excluded so that the findings would not be diluted by cases in which there was such an obvious explanation for both short umbilical cords and psychomotor impairments. Birth weights and head circumferences were included in two of the analyses as percentiles from fetal growth curves. 1~ An effort was made to separate the correlation of cord length from the effects of genetic factors and parerital child-raising practices on psychomotor development. To do this, intrapair differences in cord length were compared with intrapair differences in psychomotor development in same-sex siblings who had been born at full term. The methods used to evaluate psychomotor performance have been previously published, n,t2 A child was recorded as having neurologic abnormalities when two or more such definite abnormalities were recorded on neurologic examination at 7 years of age: The statistical methods used were the chi-square test for paired data, and stepwise multiple regression analysis. In one of the multiple regression analyses, cord length was deliberately placed last in the order of independent variables to try to determine whether its correlation with psychomotor .impairments was independent of other factors that correlate with such impairments. This analysis was then repeated, placing I-minute Apgar scores just before cord length, to see if any part of the correlation between short cords and subsequent psychomotor impairments was due to intrapartum hypoxia caused by undetected cord trauma or compression during delivery. One-minute Apgar scores have long been considered a good marker for intrapartum hypoxia, although other factors can also affect such scores. RESULTS Umbilical cords progressively lengthened from a mean of 32 cm at 20 weeks of gestation to 60 m m at term (Table I). The rate of growth slowed progressively during this period, and was very slow after 35 weeks. Cord lengths had a positive correlation with maternal pregravid weight, height, socioeconomic status, pregnancy weight gain, and the fetus being male (Table II). Only 6% of the umbilical cords were --<40 cm long at 40 to 41 weeks of gestation, so 40 cm was used as the dividing line between short and normal cord lengths in full-term neonates. 6 Short cords were associated with the need for positive pressure resuscitation at birth, low Apgar scores, hypotonia, and jitters and tremulousness in the neonatal period; short cords doubled or tripled the prognostic value of some of these markers for subsequent low IQ values and neurologic abnormalities (Table III). The correlation of short cords with low IQ values and with neurologic abnormalities was independent of birth weights and mea-
Umbilical cord length
279
Table I. Umbilical cord length at various gestational ages Gestational age (wk)
20 to 22 to 24 to 26 to 28 to 30 to 32 to 34 to 36 to 38 to 40 to 42 to 44 to 46 to
21 23 25 27 29 31 33 35 37 39 41 43 45 47
n
Umbilical cord length (cm)
16 27 38 59 80 it3 337 857 3,153 10,083 13,841 4,797 1,450 492
32.4 36.4 40.1 42.5 45.0 47.6 50.2 52.5 55.6 57.4 59.6 60.3 60.4 60.5
_+ 8.6 _+ 9.0 _+ lO.i +_ 11.3 _ 9.7 _+ 11.3 + 12.1 +_ 11.2 + 12.6 + 12.6 + 12.6 _+ 12.7 _ 12.7 + i3.0
Data represent mean -+ 1 SD.
Table II. Stepwise multiple regression analysis for relationship to umbilical cord length
Maternal pregravid body weight Maternal pregnancy weight gain Male sex of fetus Socioeconomic index value Maternal height Neonatal Hgb level Pregnancy-induced hypertension White race Maternal mental retardation Maternal chronic hypertension Maternal alcoholism Maternal narcotic addiction Maternal cigarette smoking
3
e
+0.112 +0.077 +0.074 +0.055 +0.017 +0.016 +0.007 +0.004 +0.004 +0.001 +0.001 -0.002 -0.003
<0.001 <0.001 <0.001 <0.001 <0.02 <0.05 >0.1 >0.1 >0.1 >0.1 >0.I >0.1 >0.1
Analysis limited to full-term gestations. Short umbilicalcords associated with low maternal body weight,low weight gain, female infants, low socioeconomicstatus, short mothers.
surements of head circumference at birth (Tables IV and V). Placing 1-minute Apgar scores just before cord length in a multiple regression analysis had no effect on the correlation of cord length with subsequent psychomotor performance (Table IV). When the cord lengths of full-term same-sex siblings differed by >20 cm, those with the shorter cords more often had low IQ values and neurologic abnormalities than did their paired siblings (Table VI). DISCUSSION This study confirms the previous findings of Mills et al. 6 that umbilical cord growth slows in the third trimester but
280
Naeye
The Journal o f Pediatrics August 1985
Table III. Relationship of short umbilical cord in c o m b i n a t i o n with various neonatal abnormalities
to children's subsequent psychomotor development. IQ <80 at 4 years o f age
Neurologic abnormalities at 7 years o f age
Umbilical cord length (cm)
Umbilical Cord length (cm)
5 to 40
I
n
Positive pressure ventilation Used 12 Not used 77 Apgar score at 5 min 0 to 6 9 7 to 1-0 77 Hypotofiia Present 10 Absent 70 Jitters/tremulousness Present 5 Absent 81 Cry Abnormal 6 Normal 80 Electroencephalogram Abnormal 7 Normal 79
41 to 80
5 to 40
41 to 80
%
n
%
P
n
%
n
%
P
at birth 12,5 6.4
50 666
5.7 4.4
<0.02 <0.005
15 66
15.8 5.4
42 641
5.2 4.2
<0,001 <0.05
12.8 6.4
44 656
8.2 4.2
<0.00l
10 69
14.5 5.7
29 659
6.7 4,2
<0.05 <0.02
27.0 5.6
28 659
11.7 4.2
<0.05 <0.02
12 66
32.4 5.3
25 64O
18.0 4.0
<0.05
22.7 5.8
21 721
7.0 3.6
<0.05 <0.001
4 86
18.2 6.2
30 821
10,0 4.1
<0.001
15.4 5.5
27 749
7.0 3.6
<0.001
i6 83
41.0 5.7
79 858
20.5 4.1
<0.05 <0.01
15.9 3.6
39 737
6.5 3.7
6 117
13.6 5.7
53 810
8.9 4.1
<0.005
<0.05
Analysis limited to full-term inf'ants.
Table IV. Stepwise multiple regression analysis for relationship to IQ values at 4 years a n d neurologic abnormalities at 7 years of age IQ values
Socioeconomic index values Maternal SRA test values White race Female infant Peak neonatal serum bilirubin level Birth weight by percentile Head circumference by percentile Length of umbilical cord One-minute Apgar scores preceding Umbilical cord length Length of umbilical cord
Neurologic abnormalities
fl
e
fl
P
+0.330 +0.260
-0.042 -0.063 -0.020 -O.O83 +O.004 -0.022 -0.023 -0.016 -0.020
<0.001 <0.001 <~0.05 <0.001 <0.02 <0.02 <0.05 <0.05
--0.017
<0.05
+0.158
<0.001
+0.095 -0,042 +0.034 +0,019 +0.043 +0,006
<0.001
+0.043
<0.001
Low IQ values or neurologicabnormalities associated with low socioeconomicstatus, low maternal test scores, nonwhite race, male infants, high neonatal bilirubin level, low birth weight, small head circumference, short umbilical cord, low Apgar score.
does not stop before term. Those investigators showed t h a t fetal sex also affects cord length. This study adds m a t e r n a l pregravid weight, height, socioeconomic Status, and pregnancy weight gain to the list of factors t h a t correlate with umbilical cord length. T h e most i m p o r t a n t finding of this study is t h a t short umbilical cords correlate with an increased frequency of
subsequent childhood m e n t a l and motor impairments. These i m p a i r m e n t s were presumably not related to intrap a r t u m cord t r a u m a or to abruptio placentae, because cases in which these abnormalities were diagnosed were excluded from the analysis. F u r t h e r evidence t h a t the psychomotor i m p a i r m e n t s associated with short cords originated before a n d not during labor a n d delivery was the
Volume 107 Number 2
Umbilical cord length
28 1
Table V, Correlations of umbilical cord length with psychomotor abnormalities by birth weight in children born at full term
_w.
IQ <80 at 4 years of age
Neurologic abnormalities at 7 years of age
Umbilical cord length (cm)
Umbilical cord length (cm)
.040
.o40,4
percentile
n
%
n
%
P
n
%
1st to 10th l l t h to 30th >30th
20 51 116
22.7 13.4 12.0
111 477 1426
12.6 12.0 9.6
<0,05 >0.1 <0.05
8 19 41
9.3 6.3 1.8
Table VL Intrapair same-sex sibling comparisons of umbilical cord lengths with long-term psychomotor development in children born at full term
t
ifferencein cord length between two siblings (cm) 0 to I0 n
%
10.1 to 20 n
%
4 years 1Q <80 Longer cords 48 10.6 19 8.2 Shorter cords 86 9.3 25 ll.1 7 years Abnormalities on neurologic examination Longer cords 131 13.7 36 14.2 Shorter cords 149 14.7 45 17.7
._
>20 n
P
12 27
5.9 13.2 <0.02
23 41
10.8 19.4 <0.05
finding that adding 1-minute Apgar scores to the analysis did not reduce the correlation of short cords with psychomotor impairments. Low 1-minute Apgar scores are widely regarded as a marker of intrapartum hypoxia. Multiple regression analysis and intrapair sibling comparisons showed that the correlation of short cords with psychomotor impairments was independent of many genetic factors, parental child-raising practices, and fetal growth retardation. Because short umbilical cords originate in developmental conditions long before labor and delivery, recorded measurements of cord length could be important when the obstetric management of labor and delivery or the clinical management of neonates is errone-
J
[
o
~
0 I
34 138 512
n
%
P
3.9 3.6 3.6
<0.05 <0.05 <0.1
ously claimed to be the cause of later mental and motor impairments.
REFERENCES
1, Gardiner JP: The umbilical cord. Surg Gynecol 34:252, 1922. 2. Rayburn WF, Beynen A, Brinkman DL: Umbilical cord length and intrapartum complications. Obstet Gynecol 57:450, 1981. 3. Miller ME, Jones MC, Smith DW: Tension: The basis of umbilical cord growth. J PEDIATR101:844, 1982. 4. Miller ME, Higginbottom M, Smith DW: Short umbilical cord: Its origin relevance. Pediatrics 67:618, 1981. 5. Moessinger AC, Blanc WA, Marone PA, Polsen DC: Umbilical cord length as an index of fetal activity: Experimental study and clinical implications. Pediatr Res 16:109, 1982. 6. Mills JL, Harley EE, Moessinger AC: Standards for measuring umbilical cord length. Placenta 4:423~ 1983. 7. Niswander KR, Gordon M: The women and their pregnancies. Philadelphia, 1972, W.B. Saunders Co. 8. Naeye RL, Dixon JB: Distortions in fetal growth standards. Pediatr Res 12:987, 1978. 9. Myrianthopolous NC, French KS: An application of the U.S. Bureau of the Census socioeconomic index to a large, diversified patient population. Soc Sci Med 2:283, 1968. 10. Lubchenco LO, Hansman C, Dressier M, Boyd E: Intrauterine growth as estimated from tiveborn birth-weight data at 24 to 42 weeks of gestation. Pediatrics 32:793, 1963. 11. Terman LM, Merill MA: Stanford-Binet Intelligence Scale. Boston, 1960, Houghton Miflin. 12. The Collaborative Study on Cerebral Palsy, Mental Retardation and Other Neurological and Sensory Disorders of Infancy and Childhood. Bethesda, Md., 1966, Department of Health, Education, and Welfare.
Richard L. Naeye, M.D. Hershey, Pennsylvania
FOR MANY YEARS physicians have recognized the mechanical consequences of an abnormally short or abnormally long umbilical cord. A length of at least 32 cm has been claimed necessary to prevent traction on the cord during vaginal delivery, so it is not surprising that shorter cords occasionally delay completion of the second stage of labor or cause placental abruptions, inversion of the uterus, cord herniation, and cord rupture. 14 Abnormally long cords increase the frequency of cord prolapse, true knots, and coiling of the cord around fetal parts, all of which can produce fetal distress through cord compression. 1-6 More recently researchers have begun to investigate what regulates cord length and to wonder if abnormal cord length might sometimes be a marker for other developmental abnormalities. 6 Miller et al. 3,4 and Moessinger et al? have published evidence that tension applied to the coi'd by fetal movements influences its length. Because central nervous system malfunction can limit fetal movements, we have attempted to determine if cord length has any prognostic value for childhood psychomotor impairments not related to easily recognized central nervous system anomalies.
From the Department of Pathology, M. S. Hershey Medical Center, The Pennsylvania State University College of Medicine. Submitted for publication Aug. 29, 1984; accepted Jan. 2, 1985. Reprint requests: Richard L. Naeye, M.D., Department of Pathology, M. S. Hershey Medical Center, Pennsylvania State University College of Medicine, Hershey, PA 17033.
278
TheJournalofPEDIATRICS
METHODS Data for the study came from 35,779 successful singleton pregnancies in the Collaborative Perinatal Study of the National institutes of Neurological and Communicative Disorders and Stroke. 7 Participants came from 13 hospitals from different areas of the United States. Details of patient selection have been previously published. 7 Umbilical cords were measured in the delivery room. The segments~ attached to the baby and the placenta were measured and the results added. Any part that had been cut out was also measured and added to give the total cord length. Gestational ages were calculated from ~he first.day of the last menstrual period. Corrections had to be made in some of these calculated ages because some mothers bled at the end of the first and second months of gestation. 8 The corrections were made by using birth weight cutoff values for each preterm gestational age to eliminate from the analyses infants who were 1 or 2 months older than the age calculated from the menstrual history. Hypertension Was considered to be present when two or more diastolic blood pressures were recorded at >--90 mm Hg during pregnancy. Alcoholism and narcotic addiction were diagnoses derived from maternal history and from observations made by the Project staff. The socioeconomic index used in the analyses combined scores for maternal education, husband's occupation, and family income. 9 Cases of abruptio placentae, umbilical cord rupture, and other recognized umbilical cord traumas were excluded so that the analyses would reflect nontraumatic correlations between cord length and psychomotor abnormalites. Cbil-
Volume 107 Number 2
dren with congenital malformations that might shorten life span were also excluded so that the findings would not be diluted by cases in which there was such an obvious explanation for both short umbilical cords and psychomotor impairments. Birth weights and head circumferences were included in two of the analyses as percentiles from fetal growth curves. 1~ An effort was made to separate the correlation of cord length from the effects of genetic factors and parerital child-raising practices on psychomotor development. To do this, intrapair differences in cord length were compared with intrapair differences in psychomotor development in same-sex siblings who had been born at full term. The methods used to evaluate psychomotor performance have been previously published, n,t2 A child was recorded as having neurologic abnormalities when two or more such definite abnormalities were recorded on neurologic examination at 7 years of age: The statistical methods used were the chi-square test for paired data, and stepwise multiple regression analysis. In one of the multiple regression analyses, cord length was deliberately placed last in the order of independent variables to try to determine whether its correlation with psychomotor .impairments was independent of other factors that correlate with such impairments. This analysis was then repeated, placing I-minute Apgar scores just before cord length, to see if any part of the correlation between short cords and subsequent psychomotor impairments was due to intrapartum hypoxia caused by undetected cord trauma or compression during delivery. One-minute Apgar scores have long been considered a good marker for intrapartum hypoxia, although other factors can also affect such scores. RESULTS Umbilical cords progressively lengthened from a mean of 32 cm at 20 weeks of gestation to 60 m m at term (Table I). The rate of growth slowed progressively during this period, and was very slow after 35 weeks. Cord lengths had a positive correlation with maternal pregravid weight, height, socioeconomic status, pregnancy weight gain, and the fetus being male (Table II). Only 6% of the umbilical cords were --<40 cm long at 40 to 41 weeks of gestation, so 40 cm was used as the dividing line between short and normal cord lengths in full-term neonates. 6 Short cords were associated with the need for positive pressure resuscitation at birth, low Apgar scores, hypotonia, and jitters and tremulousness in the neonatal period; short cords doubled or tripled the prognostic value of some of these markers for subsequent low IQ values and neurologic abnormalities (Table III). The correlation of short cords with low IQ values and with neurologic abnormalities was independent of birth weights and mea-
Umbilical cord length
279
Table I. Umbilical cord length at various gestational ages Gestational age (wk)
20 to 22 to 24 to 26 to 28 to 30 to 32 to 34 to 36 to 38 to 40 to 42 to 44 to 46 to
21 23 25 27 29 31 33 35 37 39 41 43 45 47
n
Umbilical cord length (cm)
16 27 38 59 80 it3 337 857 3,153 10,083 13,841 4,797 1,450 492
32.4 36.4 40.1 42.5 45.0 47.6 50.2 52.5 55.6 57.4 59.6 60.3 60.4 60.5
_+ 8.6 _+ 9.0 _+ lO.i +_ 11.3 _ 9.7 _+ 11.3 + 12.1 +_ 11.2 + 12.6 + 12.6 + 12.6 _+ 12.7 _ 12.7 + i3.0
Data represent mean -+ 1 SD.
Table II. Stepwise multiple regression analysis for relationship to umbilical cord length
Maternal pregravid body weight Maternal pregnancy weight gain Male sex of fetus Socioeconomic index value Maternal height Neonatal Hgb level Pregnancy-induced hypertension White race Maternal mental retardation Maternal chronic hypertension Maternal alcoholism Maternal narcotic addiction Maternal cigarette smoking
3
e
+0.112 +0.077 +0.074 +0.055 +0.017 +0.016 +0.007 +0.004 +0.004 +0.001 +0.001 -0.002 -0.003
<0.001 <0.001 <0.001 <0.001 <0.02 <0.05 >0.1 >0.1 >0.1 >0.1 >0.I >0.1 >0.1
Analysis limited to full-term gestations. Short umbilicalcords associated with low maternal body weight,low weight gain, female infants, low socioeconomicstatus, short mothers.
surements of head circumference at birth (Tables IV and V). Placing 1-minute Apgar scores just before cord length in a multiple regression analysis had no effect on the correlation of cord length with subsequent psychomotor performance (Table IV). When the cord lengths of full-term same-sex siblings differed by >20 cm, those with the shorter cords more often had low IQ values and neurologic abnormalities than did their paired siblings (Table VI). DISCUSSION This study confirms the previous findings of Mills et al. 6 that umbilical cord growth slows in the third trimester but
280
Naeye
The Journal o f Pediatrics August 1985
Table III. Relationship of short umbilical cord in c o m b i n a t i o n with various neonatal abnormalities
to children's subsequent psychomotor development. IQ <80 at 4 years o f age
Neurologic abnormalities at 7 years o f age
Umbilical cord length (cm)
Umbilical Cord length (cm)
5 to 40
I
n
Positive pressure ventilation Used 12 Not used 77 Apgar score at 5 min 0 to 6 9 7 to 1-0 77 Hypotofiia Present 10 Absent 70 Jitters/tremulousness Present 5 Absent 81 Cry Abnormal 6 Normal 80 Electroencephalogram Abnormal 7 Normal 79
41 to 80
5 to 40
41 to 80
%
n
%
P
n
%
n
%
P
at birth 12,5 6.4
50 666
5.7 4.4
<0.02 <0.005
15 66
15.8 5.4
42 641
5.2 4.2
<0,001 <0.05
12.8 6.4
44 656
8.2 4.2
<0.00l
10 69
14.5 5.7
29 659
6.7 4,2
<0.05 <0.02
27.0 5.6
28 659
11.7 4.2
<0.05 <0.02
12 66
32.4 5.3
25 64O
18.0 4.0
<0.05
22.7 5.8
21 721
7.0 3.6
<0.05 <0.001
4 86
18.2 6.2
30 821
10,0 4.1
<0.001
15.4 5.5
27 749
7.0 3.6
<0.001
i6 83
41.0 5.7
79 858
20.5 4.1
<0.05 <0.01
15.9 3.6
39 737
6.5 3.7
6 117
13.6 5.7
53 810
8.9 4.1
<0.005
<0.05
Analysis limited to full-term inf'ants.
Table IV. Stepwise multiple regression analysis for relationship to IQ values at 4 years a n d neurologic abnormalities at 7 years of age IQ values
Socioeconomic index values Maternal SRA test values White race Female infant Peak neonatal serum bilirubin level Birth weight by percentile Head circumference by percentile Length of umbilical cord One-minute Apgar scores preceding Umbilical cord length Length of umbilical cord
Neurologic abnormalities
fl
e
fl
P
+0.330 +0.260
-0.042 -0.063 -0.020 -O.O83 +O.004 -0.022 -0.023 -0.016 -0.020
<0.001 <0.001 <~0.05 <0.001 <0.02 <0.02 <0.05 <0.05
--0.017
<0.05
+0.158
<0.001
+0.095 -0,042 +0.034 +0,019 +0.043 +0,006
<0.001
+0.043
<0.001
Low IQ values or neurologicabnormalities associated with low socioeconomicstatus, low maternal test scores, nonwhite race, male infants, high neonatal bilirubin level, low birth weight, small head circumference, short umbilical cord, low Apgar score.
does not stop before term. Those investigators showed t h a t fetal sex also affects cord length. This study adds m a t e r n a l pregravid weight, height, socioeconomic Status, and pregnancy weight gain to the list of factors t h a t correlate with umbilical cord length. T h e most i m p o r t a n t finding of this study is t h a t short umbilical cords correlate with an increased frequency of
subsequent childhood m e n t a l and motor impairments. These i m p a i r m e n t s were presumably not related to intrap a r t u m cord t r a u m a or to abruptio placentae, because cases in which these abnormalities were diagnosed were excluded from the analysis. F u r t h e r evidence t h a t the psychomotor i m p a i r m e n t s associated with short cords originated before a n d not during labor a n d delivery was the
Volume 107 Number 2
Umbilical cord length
28 1
Table V, Correlations of umbilical cord length with psychomotor abnormalities by birth weight in children born at full term
_w.
IQ <80 at 4 years of age
Neurologic abnormalities at 7 years of age
Umbilical cord length (cm)
Umbilical cord length (cm)
.040
.o40,4
percentile
n
%
n
%
P
n
%
1st to 10th l l t h to 30th >30th
20 51 116
22.7 13.4 12.0
111 477 1426
12.6 12.0 9.6
<0,05 >0.1 <0.05
8 19 41
9.3 6.3 1.8
Table VL Intrapair same-sex sibling comparisons of umbilical cord lengths with long-term psychomotor development in children born at full term
t
ifferencein cord length between two siblings (cm) 0 to I0 n
%
10.1 to 20 n
%
4 years 1Q <80 Longer cords 48 10.6 19 8.2 Shorter cords 86 9.3 25 ll.1 7 years Abnormalities on neurologic examination Longer cords 131 13.7 36 14.2 Shorter cords 149 14.7 45 17.7
._
>20 n
P
12 27
5.9 13.2 <0.02
23 41
10.8 19.4 <0.05
finding that adding 1-minute Apgar scores to the analysis did not reduce the correlation of short cords with psychomotor impairments. Low 1-minute Apgar scores are widely regarded as a marker of intrapartum hypoxia. Multiple regression analysis and intrapair sibling comparisons showed that the correlation of short cords with psychomotor impairments was independent of many genetic factors, parental child-raising practices, and fetal growth retardation. Because short umbilical cords originate in developmental conditions long before labor and delivery, recorded measurements of cord length could be important when the obstetric management of labor and delivery or the clinical management of neonates is errone-
J
[
o
~
0 I
34 138 512
n
%
P
3.9 3.6 3.6
<0.05 <0.05 <0.1
ously claimed to be the cause of later mental and motor impairments.
REFERENCES
1, Gardiner JP: The umbilical cord. Surg Gynecol 34:252, 1922. 2. Rayburn WF, Beynen A, Brinkman DL: Umbilical cord length and intrapartum complications. Obstet Gynecol 57:450, 1981. 3. Miller ME, Jones MC, Smith DW: Tension: The basis of umbilical cord growth. J PEDIATR101:844, 1982. 4. Miller ME, Higginbottom M, Smith DW: Short umbilical cord: Its origin relevance. Pediatrics 67:618, 1981. 5. Moessinger AC, Blanc WA, Marone PA, Polsen DC: Umbilical cord length as an index of fetal activity: Experimental study and clinical implications. Pediatr Res 16:109, 1982. 6. Mills JL, Harley EE, Moessinger AC: Standards for measuring umbilical cord length. Placenta 4:423~ 1983. 7. Niswander KR, Gordon M: The women and their pregnancies. Philadelphia, 1972, W.B. Saunders Co. 8. Naeye RL, Dixon JB: Distortions in fetal growth standards. Pediatr Res 12:987, 1978. 9. Myrianthopolous NC, French KS: An application of the U.S. Bureau of the Census socioeconomic index to a large, diversified patient population. Soc Sci Med 2:283, 1968. 10. Lubchenco LO, Hansman C, Dressier M, Boyd E: Intrauterine growth as estimated from tiveborn birth-weight data at 24 to 42 weeks of gestation. Pediatrics 32:793, 1963. 11. Terman LM, Merill MA: Stanford-Binet Intelligence Scale. Boston, 1960, Houghton Miflin. 12. The Collaborative Study on Cerebral Palsy, Mental Retardation and Other Neurological and Sensory Disorders of Infancy and Childhood. Bethesda, Md., 1966, Department of Health, Education, and Welfare.