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The postmature baby
THE POSTMATURE BABY BEATRICE (From The
E. TUCKER, M.D., AND HARRY B. W. BENARON,
the Service
of the Chicago
Departmentof
Obstetrics
M.D., CHICAGO, ILL.
Maternity Center, Chicago Wesley ibfemorial Hospital, and and Gynecology, Northwestern University Medical School)
A
STUDY has been made of 4,106 infants delivered by primiparous women on the service of the Chicago Maternity Center in the ten-year period 1944 through 1953. Postmaturity is defined in terms of gestational age as calculated from the first day of the last menstrual period. A baby is postmature if the gestational age is 43 weeks or over. Firstborn babies were selected for study because the menstrual history of the primiparous woman was less erratic than that of the multiparous one. In the latter, frequent pregnancies gave rise to irregularities in the cycle. The population was divided into white and Negro groups. The incidence of postmaturity was ascertained in each. The effect of prolonged gestation on infant mortality and the size of the fetus was studied. The degree of confidence which could be placed in gestational age as a method for determining fetal development was tested. Chi square was used on the data where indicated.” Nesbit’ has recently written a comprehensive and excellent review of thr literature in “Prolongation of Pregnancy.” His bibliography is complete and it is doubtful if anyone can improve upon his presentation. The discussion which follows reflects the highlights of his paper to which are added references to the work of Clifford and Smith. An amazing amount of interest has been shown recently in the subject of the postmature baby. Until five or six years ago little appeared in the literature in this country on prolonged gestation. Many physicians doubted the validity of postmaturity and others considered that if it did exist, it was of no clinical importance. The possibility of postmaturity is now being recognized. Most a,ut,hors consider a baby postmature if the gestational age is 43 weeks or over. The incidence quoted is from 3 to 8 per cent.2-G Some define postmaturity in terms of size in addition Taogestational age. By this criterion the gestational age is 43 weeks or over, the baby weighs 4,000 grams or more and measures 53 to 56 cm. The baby is thought to increase progressively in size during the postmature period. Wrigley7 believed this to be true. Karn and Penrose8 in a study of 14,000 infants found a gradual increa,se in weight for two weeks beyond term, after which the weight is constant or slightly lower. Bone growth as determined by the time of the appearance of various ossification centers has also been used to define postmaturity.Q9 *O Tables are available which display the usual time of appearance of these centers.” Roentgenography is used to visualize the fetal skeleton. The ossification center in the distal end of the epiphysis of the femur can frequently be seen before *Chi squat-e is a formula which ascertains the probability parative statistical data. 1314
of chance occurrence of com-
POSTMATURE
BABY
1315
birth. Unfortunately, there is too great a variation in the time of its appearance (35 to 44 weeks)ll to make its presence or absence of value in the diagnosis of gestational age. SmithI and CliffordI found that the postmature baby is relatively light in weight compared to its length. They noted the following characteristics : there is little vernix; the skin is loose, wrinkled, exfoliating, and meconium stained, and the nails are long. They found that the perinatal mortality rate is higher than in the mature baby. The postulation is made that the condition of the infant is due to changes which occur in the placenta due to aging. These prevent an adequate transfer of oxygen and metabolites from the mother to the baby. The baby consequently suffers from anoxia and malnutrition. Depending upon the degree of impairment, death may occur before, during, or after labor. In other cases the child survives. At times the clinical course in the postpartum period is similar to that displayed in hyaline membrane discase. The vagaries of placental function and morphology have not been determined in prolonged gestati0n.l Masters and Clayton14 concluded that postmature placentas show no more degeneration than mature placentas. HillI found that 40 per cent of postmature placentas showed evidence of infarction and calcification. McKiddie16 postulated that microscopy and chemical analysis of the placenta might not necessarily show changes indicative of a hampered physiology. Opinions differ as to the significance of prolonged gestation in regard to survival of the infant. While Hi1115 concluded that “postmaturity does not affect adversely the mother, her labor or her infant,” Clifford13 of the Boston Lying-in Hospital stated that “in the primiparous woman postmaturity is second only to prematurity as a cause of infant death.” Walker,17 an English observer, found in 11,051 patients of all parities, that the stillbirth rate was three times as high at 43 weeks’ gestation and over as at 40 weeks. ClaytorP and Rathbunlg found no increase in the stillbirth rate without evident cause. They found that the higher mortality rate is due to difficult labor and delivery. No infant died as a direct result of the prolongation of pregnancy. Wrigley,7 Calkins,*O Eastman,21 and Daichman and Gold6 felt that there is no problem with postmaturity. Daichmane stated that the case of postmaturity should receive the same management as that of the mature infant. He believes the t.erm “postmaturity” dangerous because it leads to unnecessary interference, with bad results. The suggestion is made that the term “post date labor” be substituted. The question arises as to what are the indications for the termination of pregnancy in cases of prolonged gestation. Until recently the attitude of obstetricians was governed by the individual case, based primarily on fetal size in relation to pelvic size. Induction was carried out if the fetus was becoming excessive in size and mild disproportion seemed likely. In case of insurmountable disproportion cesarean section was done. During the past fifteen years elective induction of labor for postmaturity has been increasingly used in many clinics in England. Impetus has been given to this practice recently through the cord blood studies of Walker. l7 He has found that there is a progressive diminution in oxygen content and saturation as pregnancy advances beyond term. Rooth and SjGstedt? are unable to substantiate Walker’s findings. They conclude that hypoxia does not explain the higher mortality in infants delivered by mothers with a gestational time longer than 294 days. Even SmithI and Clifford,13 who believe that prolonged gestation has a direct bearing on infant mortality, are guarded in recommending t.he termination of pregnancy by induction or cesarean section.
Incidence Of the 4,106 children, 832 were whil-e and 3,274 were Negro. In 32 of the white and in 45 of the Negro mothtbrs the (late of t,hc last menstrual period was not known or the cycle recurred irregularly. The babies of these mothers were deducted from each group, respectively. Table I shows t,he incidence of postmaturity. The incidence in the white group is 9 per cent; in the Negro, 6 per cent. The higher incidence in t,hc white group probably has no signifigiven from maternal recollection regarding the date cance. The information of the last menstrual period was less rcliablp in the white patient.” TABLE
I.
THE
INCIDENCE
OF POSTMATURITY CHICAGO MATERNITP --LAST
RACE
White Negro
Total
TOTAL NO. 832 3,274 4,106
IN THE FIRSTBORN RABIES CENTER, 1944-1954
MENSTRUAL B 32 45 77
Perinatal
I
Infant
PER1011 KNOWN -/-___800 3,229 4.029
DELIVERED
POSTMATURE NO, / 75
192 267
AT THE
BABIES s 9.3
-y
5.9 6.6
Mortality
The perinatal mortality rate was determined for white and Negro mature and postmature infants. A mature ba.by weighs 2,500 grams or over. The perinatal deaths include intrauterine deaths and neonatal deaths. Intrauterine death occurs either ante partum or during labor and the baby is born dead. Neonatal death occurs during the first month of life. The number of mature babies was calculated by subtracting from the total the number of prematures, postmatures, and the babies born of mothers whose last menstrual period was unknown or whose cycle recurred irregularly. A premat,ure baby weighs less than 2,500 grams. Two infant deaths were deducted from the Negro postmature group. In one case the baby died during the forty-second week of pregnancy and was delivered one week later. This death was assigned to the mature group. In t,he second instance the infant was a twin, the second baby. The first twin lived. The gestational age was 48 weeks. The baby weighed 2,200 grams. The pathologist stated that the baby appeared to be a premature of about 36 weeks’ gestation. The mother gavr a history of markedly irregular menstrual periods. This death was not assigned to either group. Table II shows the perinatal mortality of the white and Negro mature and postmature babies. The percentage of loss in t,hc white group is 1.4, compared with 1.3 in the postmature group. The percentage of Negro mature babies lost is 2.3, compared with 3.1 in the postmature group. There is no statistically significant difference in the perinatal mortality rat,cs of either the white or the Negro mature and postmature groups (P = .17). A study was made of the perinatal records of the 7 babies, one white and 6 Negro, lost in the postmature group. In 2 patients pregnancy was diagnosed in the first trimester. The gesta,tional ages varied from 43 to 4’7 weeks. Two of the mothers had syphilis and were treated during pregnancy. Five had toxemia. The blood pressure ranged from 150/110 in one patient to HO/140 in another. Three of the paCents had albuminuria. Five of the 7 were deThe labors lasted from 27 to 71 hours. In 2, livered after prolonged labor. *The date of the last menstrual period is recorded twice on each perinatai WCord, once at the flrst visit on the prenatal record and again at the time of delivery on the laboGLE;; ord. A discrepancy in the two recordings occurred more often in the white a discrepancy did occur the most plausible date was chosen for the calcula voup. Ion of gestational age.
Volume Number
73 6
POSTMATURE
1317
BABY
the babies died early in labor and were delivered by craniotomy. Two were persistent posterior presentations, delivered after manual rotation by forceps. There were 3 breech deliveries. Four of the babies were large, weighing from 3,700 to 4,300 grams. There were no antepartum intrauterine deaths; 4 died intra partum and 3 died neonatally. Autopsies were performed on 6 of the 7 babies. One breech baby died from interstitial and periarterial emphysema secondary to resuscitation by tracheal catheter. A second breech baby died neonatally from pncumonia probably secondary to intrauterine asphyxia The autopsies were noncont.ributory as to the cause of death in the intrapartum group. It will be seen that each deat,h could have been due either to difficult labor and delivery, or toxemia, or infection. We agree with Nesbit’ who states, “It is fallacious to at.tribute total fetal mortality to any single factor such as postmaturity without correcting for associated clinical and pathological conditions. ” Only one of these deaths might possibly have been due to prolonged gestation. This will be discussed below. TABLE
II.
THE PERINATAL MORTALITY RATE OF WHITE AND NEGRO MATURE AND POSTMATURE FIRSTBORN RAEIES AT THE CHICAGO MATERNITY CENTER, 1944-1954 DEATHS RACEAND GESTATIONAI, .A(:F. NO. RABIES NO. I I $6 I
White.-
Unusual
Mature Postmature
634 75
9 1
1.4 1.3
Negro.Mature Postmature
2,611 192
61 6
23 3.1
Ratio
of Weight
to Length Associated With Intrauterine Death
Placental
Pathology
and
The theory has been advanced that in prolonged gestation changes occur in the placenta due to aging which cause anoxia and malnutrition, which lead to intrauterine or neonatal death. Two cases are presented which possibly but not conclusively support this theory. One was that of a premature baby, classified as such by weight and gestational age. The mother’s prenatal course was not remarkable. This baby was delivered spontaneously after a thirty-one-hour labor at the thirty-seventh week of gestation. It weighed 2,200 grams and measured 49 cm. Intrauterine death occurred two hours prior to birth. The body was meconium stained and poorly nourished. No cause of death was found at autopsy. Xecondary centers of ossification were present and the pathologist remarked that t,he tissues examined could not have been those of a premature baby. The p1acent.a was very small and thin. One-fourth of the tissue was replaced by infarcts. Another large part was nonfunctional because of a clot in one of the larger vessels. The second case was that of a postmature baby of 47 weeks’ gestation. The mother had a positive Wassermann test and received what was thought to be adequate antisyphilis treatment during the seventh month of pregnancy. This baby was born in breech presentation and died late in the second stage of labor which lasted two and a half hours. The delivery was spontaneous. The baby weighed 2,500 grams and was 51 cm. long. The attendant noted that the baby was emaciated and meconium stained. At autopsy no evidence of syphilis was found in either the baby or t,he placenta. Petechiae characteristic of anoxia were found in the lungs and heart. About half of the subst.ance
of the placenta was replated by granular infarcts. Microscopic examinatiofl disclosed t,hat most, of the villi were degenerated and buried in fibroid material.
The Effect of Postmaturity on Infant Weight The effect of postmaturity on infant weight was studied. The birth weights of the babies in the white and Negro mature and postmature groups were compared. The babies were all born at home and weighed on spring scales. Whatever error which may have occurred in weight is for the purposes of this study considered constant. The babies were divided into four groups by weight: 2,500 to 2,700 grams , 2,700 to 3,200 grams, 3,200 6o 3,700 grams and 3,700 grams and over. The data are shown in Table III. The largest number of mature white babies fell into the 3,200 gram division, while t.he largest number of mature Negro babies weighed 500 grams less and fell int,o the 2,700 gram group. The percentage of large babies was higher and the percentage of small babies was less in both the white and the Negro postmature groups. This is statistically significant ; P is less than 0.001. TABLE
III.
THE BIRTH WEIGI~TS OF WHITE AND NEGRO MATURE AND POSTMATURE INFANTS AT THE CHICAGO MATERNITV CENTER, 1944-1954 (P < 0.001)
2,500 GRAMS NO. 1 %
White.-
WEIGHT 1 2,700GRAMS 1 3,200G~aMS 1 NO. 1 ___% t NO. ) %
FIRSTBORN ---__-zzz
I3,700GRAMS+ 1 NO. 1 %
TOTAL NO. -__1 %
Mature Postmature
46 2
7.2 2.6
154 17
29 22
244 28
38.5 39
160 28
25.3 36.4
634 75
100 100
Negro.Mature Postmature
223 5
8.5 2.4
992 60
38 31
887 82
34 43
509 45
19.5 23.6
2,611 192
100 100
The problem was approached from a different angle. The incidence of postmaturity of large and of average-sized babies was ascertained and compared. The data presented are taken from a study in progress on “The Larger Babies Born on the Service of the Chicago Maternity Center.” This includes all babies that weighed 4,500 grams and over born during the twenty-year period, 1934-1954. During this time there were 55,246 deliveries. Among these were 1,507 large babies. In 45 t,he date of the last menst,rual period was not known or it recurrecl irregularly. These were deducted, leaving 1,462. The gestational age was determined for each child and compared with the gestational ages of 1,005 average-sized babies whose mothers had last menstrual periods of known date a,nd regular cycles. The latter group was made up of samplings chosen at random. Every fifty-t,hird chart in the series was pulled and the date of delivery noted. The chart of the 3,200 gram baby born nearest to this date was studied. Table IV gives the gestational ages of the large and average-sized babies born to mothers of all parities and races (white, Negro, and one Chinese). TABLE IV. (3,200
GESTATIONAL AGE OF LARGE (4,500 GRAM AND OVER) BABIES AND AVERAGE-SIZED GRAM) BABIES BORN OF MOTHERS OF ALL RACES AND PARITIES ON THE SERVICE OF THE CHICAGO MATERNITY C~~~~~,1934-1954 (P < 0.0001). ~__ GESTATIONAL AGE -TOTAL LESS THAN 43 WEEKS I1 43 WEEKS AND OVER NO. WEIGHT NO. 1 NO. 7%-I % % I 4,500 grams+ 1,237 85 225 15 1,462 100 3,200 grams* 942 93.7 6.3 3!L!!E!-100 ____ ____- 63 *Sampling.
POSTMATURE
Table V shows the gestational Negro and white babies. TABLE
BABY
ages of large and average-sized
V. THE INCIDENCE OE‘ VARIOUS GESTATIONAL SIZED FIRSTBORN BABIES, CHICAGO MATERNITY I
WEIQHT 4,500 grams+ 3,20Ograms* *Sampling.
1319
GESTATIONAL LESS THAN 43 WEEES 1 NO. % I
firstborn
AGES OF THE LARGE AND THE AVERAGECENTER, 1934-1954 (P = 0.11)
AGE 43 WEEKS AND OVER NO. % I 14 7
I TOTAL NO. 64 174
I
% 100 100
The incidence of postmaturity for la,rge babies, 4,500 grams and over, is 15 per cent, as compared with 6 per cent for average-sized babies. Statistically this is highly significant. More large babies are postmature than average-sized babies. The infant mortality rate of the large babies was three times as great as that of the average-sized babies. None of these babies died as a direct result of postmaturity. Over 60 per cent were lost because of shoulder dystoeia. In a hospital where anesthesia is readily available, this figure undoubtedly would have been less. The degree of confidence which can be placed in gestational age, as calculated from the first day of the last menstrual period, as a method of determining fetal development was tested. The degree of development after birth is usually determined by weight. A premature baby weighs less than 2,500 grams. Such a baby usually has a gestational age of less than 38 weeks. The percentage of white premature babies with a gestational age of 38 weeks or over was determined and the percentage of white mature babies with a gestational age of less than 38 weeks was determined. There were 91 premature infants among the 832 white firstborn infants and 30 of these, or 27 per cent, had a gestational age of 38 weeks or more. Of the 632 white mature infants, 176, or 28 per cent, had a gestational age of less than 38 weeks. We conclude that gestational age is a very crude method of ascertaining fetal development. Summary Of the 4,106 firstborn infants, 832 were white and 3,274 Negro. The incidence of postmaturity in the white group was 9 per cent and in the Negro group, 6 per cent. The perinatal mortality rate in the mature white group was 1.4 per cent; in the postmature white group, 1.3 per cent. The perinatal mortality rate in the mature Negro group was 2.3 per cent; in the postmature Negro group, 3.1 per cent. Two small babies died of malnutrition and anoxia during labor. The placenta of each showed changes which might have been attributed to aging. There were 5 per cent fewer small babies (2,500 grams) in the postmature white group than in the mature white group. There were 6 per cent fewer small babies in the postmature Negro group than in the mature Negro group. In the ma.ture white group the largest number of babies fell into the 3,200 gram division. This was also the largest division in the postmature white group. There was a 1 per cent increase in 3,200 gram babies and a 10 per cent increase in babies weighing 3,700 grams and over in the postmature white group over the mature white group.
In the mature Negro group thcl largest. n~unbe~* of babies 1’(zII into the 2,700 gram division, while in the postmaturtl Negro gmup t,hc largest. number There was a 13 pc’r cent incrtlase in 3,200 fell into the 3,200 gram division. gram babies and iI, 3 pc’r vacant incrc~asc ilt l)al)icts \vho weighed :?,‘7C)Ograins and over in the postmat,urc Negro group o\‘or the nmturc Negro group. From a study of “The Larger Babies Thorn at the Chicago Maternity Ckntcr,” the incidence of postmaturity for large babies (4,500 grams and over) born of mothers of all races and parities is ‘i pc~ cent greater than for avcragesized babies (3,200 grams). The same increase in the incidence of postmaturity is found for large firstborn babies over average-sized firstborn children. Twenty-seven per cent of white premature babies classified by weight fall into the mature group when classified by gestational age. Twenty-eight per cent of mature babies classified by weight. fall into the premature group when classified by gclstational age.
Conclusions There is a high degree of error in determining fetal development by gestational age and any conclusion drawn from a study such as this must be evaluated accordingly. The incidence of postmaturity is 6.6 per cent (total population). There is no statistically significant difference in the perinatal mortality rates of mature and postmature infants. Prolonged gestation is rarely accompanied by placental changes which iead to malnutrition, anosia, and death. Postmature babies tend to be larger than mature babies. The incidence of postmaturity is 7 per cent higher in large babies than in average-sized babies. The case of a postmature irifant requires no different management than that of the mature infant.
References 1. 2. 3. 4. 5. ;: if: 10. 11. 12. 13. 14. 15. 16. 17. 18. ii: 2:
Nesbit, R. E. L., Jr.: Obst. & Gynec. Surv. 10: 311, 1955. Eastman, N. J.: Editorial, Obst. & Gynec. Surv. 5: 813, 1949. Kortenoever, J. I).: Obst. & Gyncc. Surv. 5: 812, 1950. McKeown, T., and Gibson, J. R.: British &I. .I. 1: 938, 1952. Am. J. Dis. Child. 82: 232, 1951. Clifford, S. H., and Reid, D. E.: Daichman, I., and Gold, E. M.: AM. J. OBST.& GYNEC. 68: 1129, 1954. Wrigley, A. J.: Proc. Roy. Sot. Med. 39: 569, 1946. Karn, M. N., and Penrose, L. S. M.: Ann. Eugenics 16: 147, 1951. Christie, A., et al.: AM. J. OBST. &I GYKSC. 60: 133, 1950. Adams. T. W.: Obst. & Gvnec. 5: 43. 1955. Potter,’ Edith L.: Pathology of the’ Fetus and the Newborn, Chicago, 1953, The Yeal Book Publishers, Inc., p. 12. Smith, Clement A.: Am: J. Dis. Child. 82: 171, 1951. Cliffofd, Stewart H.: J. Pediat. 44: 1, 1954. J. Obst. & Gynaec. Brit. Emp. 47: 437, 1940. Masters, M., and Clayton, 8. G.: Hill, G.: J. Obst. & Gynaec. Brit. Emp. 59: 807, 1952. MeKiddie, J. M.: J. Obst. & Gynaec. Brit. Emp. 56: 386, 1949. Oxygen Levels in Human Umbilical Cord Blood. Anoxia of the Newborn Walker, J.: Infant, A Symposium, Springfield, Ill., 1953, Charles C Thomas, p, 158. J. Obst. & Gynaec. Brit. Emp. 48: 450, 1941. Clayton, S. G.: Rathbun, L. S.: AX J. OBST. L GYNEC. 46: 278,1943. AM. J. OBST. & GYNEC. 56: 167,1948. Calkins, L. A.: AM. J. OBST. & GYNEC. 67: 701, 1954. Eastman, N. J.: Personal communication to be published in The Laneet. Rooth, G., and SjGstedt, 8.:
E. TUCKER, M.D., AND HARRY B. W. BENARON,
the Service
of the Chicago
Departmentof
Obstetrics
M.D., CHICAGO, ILL.
Maternity Center, Chicago Wesley ibfemorial Hospital, and and Gynecology, Northwestern University Medical School)
A
STUDY has been made of 4,106 infants delivered by primiparous women on the service of the Chicago Maternity Center in the ten-year period 1944 through 1953. Postmaturity is defined in terms of gestational age as calculated from the first day of the last menstrual period. A baby is postmature if the gestational age is 43 weeks or over. Firstborn babies were selected for study because the menstrual history of the primiparous woman was less erratic than that of the multiparous one. In the latter, frequent pregnancies gave rise to irregularities in the cycle. The population was divided into white and Negro groups. The incidence of postmaturity was ascertained in each. The effect of prolonged gestation on infant mortality and the size of the fetus was studied. The degree of confidence which could be placed in gestational age as a method for determining fetal development was tested. Chi square was used on the data where indicated.” Nesbit’ has recently written a comprehensive and excellent review of thr literature in “Prolongation of Pregnancy.” His bibliography is complete and it is doubtful if anyone can improve upon his presentation. The discussion which follows reflects the highlights of his paper to which are added references to the work of Clifford and Smith. An amazing amount of interest has been shown recently in the subject of the postmature baby. Until five or six years ago little appeared in the literature in this country on prolonged gestation. Many physicians doubted the validity of postmaturity and others considered that if it did exist, it was of no clinical importance. The possibility of postmaturity is now being recognized. Most a,ut,hors consider a baby postmature if the gestational age is 43 weeks or over. The incidence quoted is from 3 to 8 per cent.2-G Some define postmaturity in terms of size in addition Taogestational age. By this criterion the gestational age is 43 weeks or over, the baby weighs 4,000 grams or more and measures 53 to 56 cm. The baby is thought to increase progressively in size during the postmature period. Wrigley7 believed this to be true. Karn and Penrose8 in a study of 14,000 infants found a gradual increa,se in weight for two weeks beyond term, after which the weight is constant or slightly lower. Bone growth as determined by the time of the appearance of various ossification centers has also been used to define postmaturity.Q9 *O Tables are available which display the usual time of appearance of these centers.” Roentgenography is used to visualize the fetal skeleton. The ossification center in the distal end of the epiphysis of the femur can frequently be seen before *Chi squat-e is a formula which ascertains the probability parative statistical data. 1314
of chance occurrence of com-
POSTMATURE
BABY
1315
birth. Unfortunately, there is too great a variation in the time of its appearance (35 to 44 weeks)ll to make its presence or absence of value in the diagnosis of gestational age. SmithI and CliffordI found that the postmature baby is relatively light in weight compared to its length. They noted the following characteristics : there is little vernix; the skin is loose, wrinkled, exfoliating, and meconium stained, and the nails are long. They found that the perinatal mortality rate is higher than in the mature baby. The postulation is made that the condition of the infant is due to changes which occur in the placenta due to aging. These prevent an adequate transfer of oxygen and metabolites from the mother to the baby. The baby consequently suffers from anoxia and malnutrition. Depending upon the degree of impairment, death may occur before, during, or after labor. In other cases the child survives. At times the clinical course in the postpartum period is similar to that displayed in hyaline membrane discase. The vagaries of placental function and morphology have not been determined in prolonged gestati0n.l Masters and Clayton14 concluded that postmature placentas show no more degeneration than mature placentas. HillI found that 40 per cent of postmature placentas showed evidence of infarction and calcification. McKiddie16 postulated that microscopy and chemical analysis of the placenta might not necessarily show changes indicative of a hampered physiology. Opinions differ as to the significance of prolonged gestation in regard to survival of the infant. While Hi1115 concluded that “postmaturity does not affect adversely the mother, her labor or her infant,” Clifford13 of the Boston Lying-in Hospital stated that “in the primiparous woman postmaturity is second only to prematurity as a cause of infant death.” Walker,17 an English observer, found in 11,051 patients of all parities, that the stillbirth rate was three times as high at 43 weeks’ gestation and over as at 40 weeks. ClaytorP and Rathbunlg found no increase in the stillbirth rate without evident cause. They found that the higher mortality rate is due to difficult labor and delivery. No infant died as a direct result of the prolongation of pregnancy. Wrigley,7 Calkins,*O Eastman,21 and Daichman and Gold6 felt that there is no problem with postmaturity. Daichmane stated that the case of postmaturity should receive the same management as that of the mature infant. He believes the t.erm “postmaturity” dangerous because it leads to unnecessary interference, with bad results. The suggestion is made that the term “post date labor” be substituted. The question arises as to what are the indications for the termination of pregnancy in cases of prolonged gestation. Until recently the attitude of obstetricians was governed by the individual case, based primarily on fetal size in relation to pelvic size. Induction was carried out if the fetus was becoming excessive in size and mild disproportion seemed likely. In case of insurmountable disproportion cesarean section was done. During the past fifteen years elective induction of labor for postmaturity has been increasingly used in many clinics in England. Impetus has been given to this practice recently through the cord blood studies of Walker. l7 He has found that there is a progressive diminution in oxygen content and saturation as pregnancy advances beyond term. Rooth and SjGstedt? are unable to substantiate Walker’s findings. They conclude that hypoxia does not explain the higher mortality in infants delivered by mothers with a gestational time longer than 294 days. Even SmithI and Clifford,13 who believe that prolonged gestation has a direct bearing on infant mortality, are guarded in recommending t.he termination of pregnancy by induction or cesarean section.
Incidence Of the 4,106 children, 832 were whil-e and 3,274 were Negro. In 32 of the white and in 45 of the Negro mothtbrs the (late of t,hc last menstrual period was not known or the cycle recurred irregularly. The babies of these mothers were deducted from each group, respectively. Table I shows t,he incidence of postmaturity. The incidence in the white group is 9 per cent; in the Negro, 6 per cent. The higher incidence in t,hc white group probably has no signifigiven from maternal recollection regarding the date cance. The information of the last menstrual period was less rcliablp in the white patient.” TABLE
I.
THE
INCIDENCE
OF POSTMATURITY CHICAGO MATERNITP --LAST
RACE
White Negro
Total
TOTAL NO. 832 3,274 4,106
IN THE FIRSTBORN RABIES CENTER, 1944-1954
MENSTRUAL B 32 45 77
Perinatal
I
Infant
PER1011 KNOWN -/-___800 3,229 4.029
DELIVERED
POSTMATURE NO, / 75
192 267
AT THE
BABIES s 9.3
-y
5.9 6.6
Mortality
The perinatal mortality rate was determined for white and Negro mature and postmature infants. A mature ba.by weighs 2,500 grams or over. The perinatal deaths include intrauterine deaths and neonatal deaths. Intrauterine death occurs either ante partum or during labor and the baby is born dead. Neonatal death occurs during the first month of life. The number of mature babies was calculated by subtracting from the total the number of prematures, postmatures, and the babies born of mothers whose last menstrual period was unknown or whose cycle recurred irregularly. A premat,ure baby weighs less than 2,500 grams. Two infant deaths were deducted from the Negro postmature group. In one case the baby died during the forty-second week of pregnancy and was delivered one week later. This death was assigned to the mature group. In t,he second instance the infant was a twin, the second baby. The first twin lived. The gestational age was 48 weeks. The baby weighed 2,200 grams. The pathologist stated that the baby appeared to be a premature of about 36 weeks’ gestation. The mother gavr a history of markedly irregular menstrual periods. This death was not assigned to either group. Table II shows the perinatal mortality of the white and Negro mature and postmature babies. The percentage of loss in t,hc white group is 1.4, compared with 1.3 in the postmature group. The percentage of Negro mature babies lost is 2.3, compared with 3.1 in the postmature group. There is no statistically significant difference in the perinatal mortality rat,cs of either the white or the Negro mature and postmature groups (P = .17). A study was made of the perinatal records of the 7 babies, one white and 6 Negro, lost in the postmature group. In 2 patients pregnancy was diagnosed in the first trimester. The gesta,tional ages varied from 43 to 4’7 weeks. Two of the mothers had syphilis and were treated during pregnancy. Five had toxemia. The blood pressure ranged from 150/110 in one patient to HO/140 in another. Three of the paCents had albuminuria. Five of the 7 were deThe labors lasted from 27 to 71 hours. In 2, livered after prolonged labor. *The date of the last menstrual period is recorded twice on each perinatai WCord, once at the flrst visit on the prenatal record and again at the time of delivery on the laboGLE;; ord. A discrepancy in the two recordings occurred more often in the white a discrepancy did occur the most plausible date was chosen for the calcula voup. Ion of gestational age.
Volume Number
73 6
POSTMATURE
1317
BABY
the babies died early in labor and were delivered by craniotomy. Two were persistent posterior presentations, delivered after manual rotation by forceps. There were 3 breech deliveries. Four of the babies were large, weighing from 3,700 to 4,300 grams. There were no antepartum intrauterine deaths; 4 died intra partum and 3 died neonatally. Autopsies were performed on 6 of the 7 babies. One breech baby died from interstitial and periarterial emphysema secondary to resuscitation by tracheal catheter. A second breech baby died neonatally from pncumonia probably secondary to intrauterine asphyxia The autopsies were noncont.ributory as to the cause of death in the intrapartum group. It will be seen that each deat,h could have been due either to difficult labor and delivery, or toxemia, or infection. We agree with Nesbit’ who states, “It is fallacious to at.tribute total fetal mortality to any single factor such as postmaturity without correcting for associated clinical and pathological conditions. ” Only one of these deaths might possibly have been due to prolonged gestation. This will be discussed below. TABLE
II.
THE PERINATAL MORTALITY RATE OF WHITE AND NEGRO MATURE AND POSTMATURE FIRSTBORN RAEIES AT THE CHICAGO MATERNITY CENTER, 1944-1954 DEATHS RACEAND GESTATIONAI, .A(:F. NO. RABIES NO. I I $6 I
White.-
Unusual
Mature Postmature
634 75
9 1
1.4 1.3
Negro.Mature Postmature
2,611 192
61 6
23 3.1
Ratio
of Weight
to Length Associated With Intrauterine Death
Placental
Pathology
and
The theory has been advanced that in prolonged gestation changes occur in the placenta due to aging which cause anoxia and malnutrition, which lead to intrauterine or neonatal death. Two cases are presented which possibly but not conclusively support this theory. One was that of a premature baby, classified as such by weight and gestational age. The mother’s prenatal course was not remarkable. This baby was delivered spontaneously after a thirty-one-hour labor at the thirty-seventh week of gestation. It weighed 2,200 grams and measured 49 cm. Intrauterine death occurred two hours prior to birth. The body was meconium stained and poorly nourished. No cause of death was found at autopsy. Xecondary centers of ossification were present and the pathologist remarked that t,he tissues examined could not have been those of a premature baby. The p1acent.a was very small and thin. One-fourth of the tissue was replaced by infarcts. Another large part was nonfunctional because of a clot in one of the larger vessels. The second case was that of a postmature baby of 47 weeks’ gestation. The mother had a positive Wassermann test and received what was thought to be adequate antisyphilis treatment during the seventh month of pregnancy. This baby was born in breech presentation and died late in the second stage of labor which lasted two and a half hours. The delivery was spontaneous. The baby weighed 2,500 grams and was 51 cm. long. The attendant noted that the baby was emaciated and meconium stained. At autopsy no evidence of syphilis was found in either the baby or t,he placenta. Petechiae characteristic of anoxia were found in the lungs and heart. About half of the subst.ance
of the placenta was replated by granular infarcts. Microscopic examinatiofl disclosed t,hat most, of the villi were degenerated and buried in fibroid material.
The Effect of Postmaturity on Infant Weight The effect of postmaturity on infant weight was studied. The birth weights of the babies in the white and Negro mature and postmature groups were compared. The babies were all born at home and weighed on spring scales. Whatever error which may have occurred in weight is for the purposes of this study considered constant. The babies were divided into four groups by weight: 2,500 to 2,700 grams , 2,700 to 3,200 grams, 3,200 6o 3,700 grams and 3,700 grams and over. The data are shown in Table III. The largest number of mature white babies fell into the 3,200 gram division, while t.he largest number of mature Negro babies weighed 500 grams less and fell int,o the 2,700 gram group. The percentage of large babies was higher and the percentage of small babies was less in both the white and the Negro postmature groups. This is statistically significant ; P is less than 0.001. TABLE
III.
THE BIRTH WEIGI~TS OF WHITE AND NEGRO MATURE AND POSTMATURE INFANTS AT THE CHICAGO MATERNITV CENTER, 1944-1954 (P < 0.001)
2,500 GRAMS NO. 1 %
White.-
WEIGHT 1 2,700GRAMS 1 3,200G~aMS 1 NO. 1 ___% t NO. ) %
FIRSTBORN ---__-zzz
I3,700GRAMS+ 1 NO. 1 %
TOTAL NO. -__1 %
Mature Postmature
46 2
7.2 2.6
154 17
29 22
244 28
38.5 39
160 28
25.3 36.4
634 75
100 100
Negro.Mature Postmature
223 5
8.5 2.4
992 60
38 31
887 82
34 43
509 45
19.5 23.6
2,611 192
100 100
The problem was approached from a different angle. The incidence of postmaturity of large and of average-sized babies was ascertained and compared. The data presented are taken from a study in progress on “The Larger Babies Born on the Service of the Chicago Maternity Center.” This includes all babies that weighed 4,500 grams and over born during the twenty-year period, 1934-1954. During this time there were 55,246 deliveries. Among these were 1,507 large babies. In 45 t,he date of the last menst,rual period was not known or it recurrecl irregularly. These were deducted, leaving 1,462. The gestational age was determined for each child and compared with the gestational ages of 1,005 average-sized babies whose mothers had last menstrual periods of known date a,nd regular cycles. The latter group was made up of samplings chosen at random. Every fifty-t,hird chart in the series was pulled and the date of delivery noted. The chart of the 3,200 gram baby born nearest to this date was studied. Table IV gives the gestational ages of the large and average-sized babies born to mothers of all parities and races (white, Negro, and one Chinese). TABLE IV. (3,200
GESTATIONAL AGE OF LARGE (4,500 GRAM AND OVER) BABIES AND AVERAGE-SIZED GRAM) BABIES BORN OF MOTHERS OF ALL RACES AND PARITIES ON THE SERVICE OF THE CHICAGO MATERNITY C~~~~~,1934-1954 (P < 0.0001). ~__ GESTATIONAL AGE -TOTAL LESS THAN 43 WEEKS I1 43 WEEKS AND OVER NO. WEIGHT NO. 1 NO. 7%-I % % I 4,500 grams+ 1,237 85 225 15 1,462 100 3,200 grams* 942 93.7 6.3 3!L!!E!-100 ____ ____- 63 *Sampling.
POSTMATURE
Table V shows the gestational Negro and white babies. TABLE
BABY
ages of large and average-sized
V. THE INCIDENCE OE‘ VARIOUS GESTATIONAL SIZED FIRSTBORN BABIES, CHICAGO MATERNITY I
WEIQHT 4,500 grams+ 3,20Ograms* *Sampling.
1319
GESTATIONAL LESS THAN 43 WEEES 1 NO. % I
firstborn
AGES OF THE LARGE AND THE AVERAGECENTER, 1934-1954 (P = 0.11)
AGE 43 WEEKS AND OVER NO. % I 14 7
I TOTAL NO. 64 174
I
% 100 100
The incidence of postmaturity for la,rge babies, 4,500 grams and over, is 15 per cent, as compared with 6 per cent for average-sized babies. Statistically this is highly significant. More large babies are postmature than average-sized babies. The infant mortality rate of the large babies was three times as great as that of the average-sized babies. None of these babies died as a direct result of postmaturity. Over 60 per cent were lost because of shoulder dystoeia. In a hospital where anesthesia is readily available, this figure undoubtedly would have been less. The degree of confidence which can be placed in gestational age, as calculated from the first day of the last menstrual period, as a method of determining fetal development was tested. The degree of development after birth is usually determined by weight. A premature baby weighs less than 2,500 grams. Such a baby usually has a gestational age of less than 38 weeks. The percentage of white premature babies with a gestational age of 38 weeks or over was determined and the percentage of white mature babies with a gestational age of less than 38 weeks was determined. There were 91 premature infants among the 832 white firstborn infants and 30 of these, or 27 per cent, had a gestational age of 38 weeks or more. Of the 632 white mature infants, 176, or 28 per cent, had a gestational age of less than 38 weeks. We conclude that gestational age is a very crude method of ascertaining fetal development. Summary Of the 4,106 firstborn infants, 832 were white and 3,274 Negro. The incidence of postmaturity in the white group was 9 per cent and in the Negro group, 6 per cent. The perinatal mortality rate in the mature white group was 1.4 per cent; in the postmature white group, 1.3 per cent. The perinatal mortality rate in the mature Negro group was 2.3 per cent; in the postmature Negro group, 3.1 per cent. Two small babies died of malnutrition and anoxia during labor. The placenta of each showed changes which might have been attributed to aging. There were 5 per cent fewer small babies (2,500 grams) in the postmature white group than in the mature white group. There were 6 per cent fewer small babies in the postmature Negro group than in the mature Negro group. In the ma.ture white group the largest number of babies fell into the 3,200 gram division. This was also the largest division in the postmature white group. There was a 1 per cent increase in 3,200 gram babies and a 10 per cent increase in babies weighing 3,700 grams and over in the postmature white group over the mature white group.
In the mature Negro group thcl largest. n~unbe~* of babies 1’(zII into the 2,700 gram division, while in the postmaturtl Negro gmup t,hc largest. number There was a 13 pc’r cent incrtlase in 3,200 fell into the 3,200 gram division. gram babies and iI, 3 pc’r vacant incrc~asc ilt l)al)icts \vho weighed :?,‘7C)Ograins and over in the postmat,urc Negro group o\‘or the nmturc Negro group. From a study of “The Larger Babies Thorn at the Chicago Maternity Ckntcr,” the incidence of postmaturity for large babies (4,500 grams and over) born of mothers of all races and parities is ‘i pc~ cent greater than for avcragesized babies (3,200 grams). The same increase in the incidence of postmaturity is found for large firstborn babies over average-sized firstborn children. Twenty-seven per cent of white premature babies classified by weight fall into the mature group when classified by gestational age. Twenty-eight per cent of mature babies classified by weight. fall into the premature group when classified by gclstational age.
Conclusions There is a high degree of error in determining fetal development by gestational age and any conclusion drawn from a study such as this must be evaluated accordingly. The incidence of postmaturity is 6.6 per cent (total population). There is no statistically significant difference in the perinatal mortality rates of mature and postmature infants. Prolonged gestation is rarely accompanied by placental changes which iead to malnutrition, anosia, and death. Postmature babies tend to be larger than mature babies. The incidence of postmaturity is 7 per cent higher in large babies than in average-sized babies. The case of a postmature irifant requires no different management than that of the mature infant.
References 1. 2. 3. 4. 5. ;: if: 10. 11. 12. 13. 14. 15. 16. 17. 18. ii: 2:
Nesbit, R. E. L., Jr.: Obst. & Gynec. Surv. 10: 311, 1955. Eastman, N. J.: Editorial, Obst. & Gynec. Surv. 5: 813, 1949. Kortenoever, J. I).: Obst. & Gyncc. Surv. 5: 812, 1950. McKeown, T., and Gibson, J. R.: British &I. .I. 1: 938, 1952. Am. J. Dis. Child. 82: 232, 1951. Clifford, S. H., and Reid, D. E.: Daichman, I., and Gold, E. M.: AM. J. OBST.& GYNEC. 68: 1129, 1954. Wrigley, A. J.: Proc. Roy. Sot. Med. 39: 569, 1946. Karn, M. N., and Penrose, L. S. M.: Ann. Eugenics 16: 147, 1951. Christie, A., et al.: AM. J. OBST. &I GYKSC. 60: 133, 1950. Adams. T. W.: Obst. & Gvnec. 5: 43. 1955. Potter,’ Edith L.: Pathology of the’ Fetus and the Newborn, Chicago, 1953, The Yeal Book Publishers, Inc., p. 12. Smith, Clement A.: Am: J. Dis. Child. 82: 171, 1951. Cliffofd, Stewart H.: J. Pediat. 44: 1, 1954. J. Obst. & Gynaec. Brit. Emp. 47: 437, 1940. Masters, M., and Clayton, 8. G.: Hill, G.: J. Obst. & Gynaec. Brit. Emp. 59: 807, 1952. MeKiddie, J. M.: J. Obst. & Gynaec. Brit. Emp. 56: 386, 1949. Oxygen Levels in Human Umbilical Cord Blood. Anoxia of the Newborn Walker, J.: Infant, A Symposium, Springfield, Ill., 1953, Charles C Thomas, p, 158. J. Obst. & Gynaec. Brit. Emp. 48: 450, 1941. Clayton, S. G.: Rathbun, L. S.: AX J. OBST. L GYNEC. 46: 278,1943. AM. J. OBST. & GYNEC. 56: 167,1948. Calkins, L. A.: AM. J. OBST. & GYNEC. 67: 701, 1954. Eastman, N. J.: Personal communication to be published in The Laneet. Rooth, G., and SjGstedt, 8.: