Int J Gynecol Obstet,
1992, 38: 181-187
181
International Federation of Gynecology and Obstetrics
Perinatal outcome of very low birthweight infants by mode of delivery J.C. Melchora, G. Arangurena, J.A. Lbpez”, M. Avila”, L. FernBndez-Llebrez” and A. Linaresb ‘Perinatal Care Unit, Department of Obstetrics and Gvnecolopv University of the Pais V&o. Crucei Hospital, Vizcaya (Spa&j
and bDepartment
of Pediatrics.
Faculty of Medicine and Dentistry,
(Received July 26th, 1991) (Revised and accepted February 7th, 1992)
Abstract In order to evaluate the influence of mode of delivery on perinatal morbidity and mortality in vertex infants weighing less than 1500 g ( VLB W), we made a retrospective study of 152 singleton newborns, in vertex presentation, with a birthweight of less than 1500 g, delivered in the Cruces Hospital (Vizcaya, Spain), a major perinatal referral center, between 1 January 1987 and 31 December 1989. Twins and infants with lethal congenital anomalies or gross intrauterine growth deviations were excluded from the study (n = 71). Of the infants studied (n = 81), 37 were delivered by cesarean section (mean weight 1120 f 206 g, range: 680-1495 g) and 44 were delivered vaginally (mean weight 1029 f 283 g, range: 530- 14 75 g) , The patients were divided into four groups: Group A: 500-749 g (n = 10); Group B: 750-999 g (n = 21); Group C: 1000-1249 g (n = 27); and Group D: 1250-1499 g (n = 23). The percentages of cesarean sections in each group were IO%, 42%, 66% and 39”/0, respectively. A comparison within each group of immediate perinatal outcome (Apgar score and umbilical vein cord pH), as well as mortality and sequelae up to 1 year of age did not yield any significant differences between cesarean and vaginal birth. We conclude that cesarean 0020-7292/92/$05.00
0 1992 International Federation of Gynecology and Obstetrics Printed and Published in Ireland
delivery does not appear to offer improved outcome over vaginal delivery in live births without congenital anomalies. For this reason, we believe that fetal weight should not be the only obstetrical variable considered when deciding whether or not to perform a cesarean section in these circumstances.
Keywords: Prematurity;
Vertex presentation; Very low birthweight; Cesarean section; Vaginal delivery; Perinatal mortality.
Introduction
One of the great challenges in perinatology today is the management of low birthweight infants and, within this group, infants weighing less than 1500 g are usually described as very low birthweight (VLBW). During the 198Os, neonatal mortality rates dropped dramatically, largely due to the improved survival of low birthweight infants [5,9]. Probably the most influential factor has been the great advances made in neonatal intensive care [5,13]. However, this factor has created a series of clinical dilemmas regarding the management of these infants both before and during birth. The optimal mode of delivery for low birthArticle
182
Melchor et al
weight infants is a matter of great controversy. Based on the work of Goldenberg and Nelson [8] cesarean section is the proposed best mode of delivery to decrease perinatal morbidity and mortality, even in vertex births. This proposal is controversial. It is postulated that vaginal delivery is preferable in a vertex birth [3,15]. To study the influence of mode of delivery on vertex infants weighing less than 1500 g, tie studied immediate perinatal outcomes and both morbidity and mortality during the first year of life of these very low birthweight babies.
1000-1249 g (n = 27); and Group D: 1250-1499 g (n = 23). For the statistical analysis, the frequencies of the different variables were determined. Comparison between two qualitative variables was made using the chi-square test (with Yates’ correction when appropriate). The Student’s t-test was used to compare means and percentages and the Mann-Whitney test was employed when the distribution of cases did not follow a normal curve. Values of P < 0.05 were considered significant.
Materials and methods
The mean age of patients was 28.5 f 5.5 years. Forty-eight patients (59%) were primiparas. The mean gestational age at delivery was 28.2 * 2.7 weeks (23-33 weeks) and the mean birthweight was 1071 * 254 g. There were 42 males (51.85%) and 39 females. It was noted that only 26 of 81 patients received tocolytic agents (Ritodrine). Using the sonogram done shortly before delivery, 26.31% of the infants showed a discrepancy (1 l-2 weeks) between fetal biometry (sonographic age) and menstrual age. Except for 10 patients (12.34%), all other deliveries presented some type of perinatal risk in addition to the prematurity itself. The most frequent were premature rupture of membranes (PROM, 26 cases), hypertension of pregnancy (17 cases) and hemorrhage during the I-II trimester (8 cases) and during the III trimester (7 cases). Other, less frequent risks were oligohydramnios without PROM (3 cases), absence of prenatal care (3 cases),
A retrospective analysis was made of 152 singleton newborns with birthweights of less than 1500 g delivered at Cruces Hospital (Vizcaya, Spain), a major perinatal referral center between 1987 and 1989. Excluded from the study were twins (n = 36), stillborns (n = 23) and infants with lethal congenital anomalies (n = 7). Infants with a low birthweight for gestational age (intrauterine growth retardation) were also excluded (n = 5). A total of 19 090 deliveries were made during the study period. Antenatal steroids had not been used. The following factors were analyzed for the study: age, parity, course of gestation, gestational age, use or not of tocolytic drugs, agreement or disagreement with sonographic measurements, course of delivery, immediate perinatal outcomes (1-min and 5-min Apgar scores and umbilical vein cord pH), gender, mortality up to 1 year of age, causes of death, length of hospital stay of the newborn (in intensive care and total length of stay in the Pediatric Unit), as well as follow up of these infants (presence or absence of sequelae and type of same) during the first year of life. The study population was divided into four birthweight groups for the analysis of some variables: Group A: 500-749 g (n = 10); Group B: 750-999 g (n = 21); Group C:
Inr J Gynecol Obster 38
Results
Table 1. Mode of delivery (%) by birthweight groups.
500-749 g 750-999 g 1000-1249 g 1250-1499 g
Vaginal delivery (n=44)
Cesarean section (n = 37)
88.9 57.2 33.3 60.9
11.1 42.8 66.7 39.1
Perinatal outcome of very low birthweight infants by mode of delivery
183
Number of cases 124
750-999
grams
1000-1249 grams Birthweight groups
1250-1499
grams
Fig. 1. Indications for cesarean section by birtbweight groups.
polyhydramnios (I case) and maternal diabetes (1 case). Five patients presented other problems. Table 1 shows the mode of delivery in each of the birthweight groups. Particularly notable is the high frequency (66.66%) of cesarean sections in the birthweight group of lOOO-1249 g. The incidence of cesarean sections in the whole population was 45.67%. The most frequent indications for cesarean
Table 2.
section were hypertension (16 cases, 43.24%) and fetal distress (9 cases, 24.32%). Eight patients elected to have a cesarean delivery due to PROM, while the indication for the other four cases was III-trimester hemorrhage (2 for placenta previa and another 2 for placental abruption). Figure 1 presents a summary of the indications for cesarean delivery by birthweight groups. An analysis of immediate perinatal out-
Immediate perinatal outcomes (1’ and 5’ Apgar test and umbilical venous pH) by birthweight and mode of delivery. 750-999 g Cesarean section (n = 9)
1’Apgar c 4 37.5 5’ Apgar c 7 12.5 Umbilical pH < 7.20 25.0
1000-1249 g
1250-1499 g
Vaginal delivery (n = 12)
Cesarean section (n = 18)
Vaginal delivery (n = 9)
Cesarean section (n = 9)
Vaginal delivery (n = 14)
41.7 33.3 40.0
16.7 0 16.7
11.1 22.2 0
22.2 0 0
0 0 33.3
P values were not significant in any of the groups studied. (No comparison could be made in the birthweight group of 500-749 g since there was only one cesarean section in this group.)
Article
184
Melchor et al.
m
VAGINAL DELIVERY
=
CESAREAN
SECTION
66,6 /
/I
60
1000-1249
g.
t groups Fig. 2. Postneonatal mortality.
come (Table 2) do not show statistically significant differences in any of the groups studied, whether the delivery was made vaginally or abdominally. Postneonatal mortality (up to 1 year of age) is shown in Fig. 2. Mortality rates are very high under 1000 g (20/3 1 cases; 64.5 lo/), while above this weight, mortality was only 18.00% (9 cases). Of 29 infants who died before 1 year of age, 20 died during the first month of life. When we analyze mortality by birthweight groups and mode of delivery, we find no significant differences. The causes of death were: sepsis (3 cases); respiratory distress syndrome (RDS) (7 cases); sepsis + RDS (5 cases); RDS + intraventricular hemorrhage (IVH) (4 cases); sepsis + RDS + IVH (8 cases) and immaturite lungs development considered to be incompatible with extrauterine survival (2 cases). There Int J Gynecol Obstet 38
were no differences between vaginal and cesarean delivery (Table 3). Figure 3 summarizes the morbidity and type of sequelae presented by the infants who did not die during the first year of life Table 3. Causes (number) of death.
Sepsis RDS Sepsis + RDS RDS+ IVH Sepsis + RDS + IVH Inmaturity Other causes
Vaginal delivery (n=44)
Cesarean section (n = 37)
1 5 2 4
2 2 3 -
5 2
3 -
1
-
RDS, Respiratory Distress Syndrome; IVH, Intraventricular Hemorrhage. x2 = 6.73; P not significant (P = 0.34616).
Perinatal outcome of very low birthweight infants by mode of delivery
Number
185
of cases
-
VAGINAL DELIVERY
@@ CESAREAN
SECTION
6
NEUROLOGIC
NO Fig. 3.
RESPIRATORY
DIGESTIVE
MALFORMATIONS
Morbidity and type of sequelae.
100 80 60 40
SURVIVAL SEQUELAE
RATES RATES
(%I (%)
I
4
30
31
32
33
100
77,7
80
63,3
100
42,8
85,7
50
40
0
I
I
I
I
25
26
27
28
29
30
28,5
50
66,6
100
100
100
53,8 Week
-
Fig. 4.
I
I
0
SURVIVAL
I
of gestation
RATES (%I--
SEQUELAE
RATES (%I
Survival and sequelae rates (tendency) for each week of gestation. Article
186
Melchor et al.
(n = 51). No statistically significant differences were found. The sequelae were classified. as neurologic problems (cerebral palsy, hydrocephalus, and other forms of impairement), respiratory problems (bronchopulmonary dysplasia, respiratory distress syndrome), digestive problems (necrotizing enterocolitis, gastro-esophageal ebb), retinopathy and no lethal congenital malformations. Three newborns developed retinopathy and 8 newborns developed more than one sequela. Figure 4 presents the survival rates at 1 year of age and the percentage of short and longterm sequelae for each week of gestation. Note that survival goes up with increasing gestational age, while the index of sequelae, very high at 25-27 weeks, goes progressively down. Discussion The most notable aspect of this study is that, based on our results, it does not appear that cesarean section has a better outcome than vaginal delivery in vertex infants weighing less than 1500 g. We found no significant differences between the two modes of delivery in any of the parameters studied immediate perinatal outcome (Apgar score and umbilical vein cord pH), mortality up to 1 year of age, and existence of sequelae - for any of the four birthweight groups analyzed at 1 year of age. Other authors have found similar results [3,10,12,15]. Vaginal delivery is now the preferred method in the case of a vertex infant estimated to weigh less than 1500 g. In contrast to the studies cited, our population was pre-selected in that it excluded twins, infants with malformations and infants with a low or high birthweight for gestational age. This was done because the initial idea was to analyze the influence of delivery mode on morbidity and mortality. These results, however, should be viewed with caution since they pertain to a retrospective study and are, therefore, biased to some Int J Gynecol Obstet 38
extent. Practically all studies made on this subject suffer from the same problem. Furthermore, the results from different centers cannot always be extrapolated to others, as was shown by Fenton [6] in his prospective review of the management of premature infants of less than 33 weeks gestation in 17 centers in England. The perinatal factors that best predict survival in low birthweight infants are gestational age and birthweight [I 11, although in infants < 1000 g birthweight is clearly a more specific indicator than gestational age [I]. Antenatal determination of fetal weight and sonographic age based on ultrasonographic measurements have quite high rates of error. Unless the date of conception is known exactly, the calculation is only an estimate which has a variation of l-2 weeks, at best [2]. We found the discrepancy between sonographic age and menstrual age to be 26.31%. This discrepancy between fetal weight as estimated by ultrasound and birthweight makes it necessary for each work site to have its own weight curves. These graphs will be of enormous help in evaluating each case and deciding which mode of delivery will be most appropriate for the low birthweight infant. In our population, 500 g of weight are reached between 22 and 23 weeks of gestation. Therefore it is no longer acceptable to limit fetal viability to 25 weeks of gestation, especially when survivals have been described under that limit [8,16]. Furthermore, the underestimation of fetal weight is generally associated with high rates of perinatal mortality. For all these reasons, we believe that the attitude taken with respect to fetal viability is as important as birthweight. Obviously, ‘attitude’ alone cannot make a baby survive; however, attitude can allow for the proper perinatal measures to be taken in order to maximize the chance of survival. A greater or lesser interest in the infant during perinatal care will in large measure condition the neonatal outcome [2,6,9]. In addition to the weight chart, it is impor-
Perinatal outcome of very low birthweight
tant to have survival rates and the percentage of infants that present sequelae, for each week of gestation (Fig. 4). These, after all, are the data that will help us make decisions in the case of a low birthweight infant. Both neurological and other types of morbidity increase in frequency as gestational age at birth goes down. In Cooke’s [4] multicenter review of gestations under 28 weeks, he found a 20-50% rate of serious neurologic sequelae. Goldenberg [8] found similar rates. However these sequelae cannot be attributed exclusively to the mode of delivery. There are undoubtedly other factors that intervene in the genesis of these problems which are probably more important than the mode of delivery, such as perinatal asphyxia, respiratory distress, neonatal trauma, perinatal care, etc. [13]. Tejani [14] even suspected that intraventricular hemorrhage may be present before delivery and that this may bring on the premature birth. In our fmdings, of the 51 infants followed up to 1 year of age, 10 (19.60%) presented neurologic sequelae and live of these were delivered by cesarean section. In conclusion, our findings, with the limitations already mentioned, indicate that cesarean section does not offer an improved outcome over vaginal delivery in vertex infants weighing less than 1500 g. Nevertheless, we believe that the decision as to the optimal mode of delivery must be made individually in each case.
4 5
6
7 8
9
10
11
12
13
14
15
16
References Amon E, Sibai BM, Anderson GD, Mabie WC: Obstetrics variables predicting survival of immature newborn ( zz 1000 gm): A live-year experience at a single perinatal center. Am J Obstet Gynecol 156: 1380, 1987. Amon E: Limits of fetal viability. Obstetrics considerations regarding the management and delivery of the extremely premature baby. Obstet Gynecol Clin N Am 15. 321, 1988. Bowes Jr. WA: Clinical management of preterm delivery. Clin Obstet Gynecol 3: 629, 1988.
infants by mode of delivery
187
Cooke RWI: Outcome and costs of care for the very immature infant. Br Med Bull 44: 1133, 1988 Ehrenhaft PM, Wagner JL, Herdman RC: Changing prognosis for very low birth weight infants. Obstet Gynecol 74: 528, 1989. Fenton A, Field DJ, Mason E, Clarke M: Attitudes to viability of preterm infants and their effect on figures for perinatal mortality. Br Med J 300: 434, 1990. Goldenberg RL, Nelson KG: The premature breech. Am J Obstet Gynecol 127: 240, 1977. Goldenberg RL, Nelson KG, Davis RO, Koski J: Delay in delivery: influence of gestational age and the duration of delay on perinatal outcome. Obstet Gynecol 64: 48C, 1984. Hack M, Fanaroff AA: Changes in the delivery room care of the extremely small infant (~750 g). Effects on morbidity and outcome. N Engl J Med 314: 660, 1986. Kitchen W, Ford GW, Doyle LW, Rickards AL, Lissenden JV, Pepperell RJ, Duke JE: Cesarean section or vaginal delivery at 24 to 28 weeks gestation: Comparison of survival and neonatal and 2-year morbidity. Obstet Gynecol 66: 149, 1985. Melchor JC, Femandez-Llebrez L, Linares A, Ariceta JM, Lopez JA, Rodriguez-Alar&n J, Corcostegui B, Aranguren G: Obstetrics variables predicting survival of immature newborn (< 1000 pm). Rev Esp Obst Ginec 2. 51, 1989. Olshan AF, Shy KK, Luthy DA, Hickok D, Weiss NS, Daling JR: Cesarean birth and neonatal mortality in very low birth weight infants. Obstet Gynecol 64: 267, 1984. Sachs BP, Ringer SA: Intrapartum and delivery room management of the very low birthweight infant. Clin Perinatol 16: 809, 1989. Tejani N, Verma U, Hameed C, Chayen B: Method and route of delivery in the low-birth-weight vertex presentation correlated with early periventricular/intraventricular hemorrhage. Obstet Gynecol 69: I, 1987. Welch RA, Bottoms SF: Reconsideration of head compression and intraventricular hemorrhage in the vertex very-low-birth-weight fetus. Obstet Gynecol 68: 29, 1986. Yu WYH, Loke HL, Bajuk B, Schymonowicz W, Orgill AA, Astbury J: Prognosis of infants born at 23 to 28 weeks’ gestation. Br Med J 293: 1200, 1986.
Address for reprints:
J.C. Mel&or Uaidad de Atencih Perinatal Hospital de Cruces Vizcaya, Spain
Article
1992, 38: 181-187
181
International Federation of Gynecology and Obstetrics
Perinatal outcome of very low birthweight infants by mode of delivery J.C. Melchora, G. Arangurena, J.A. Lbpez”, M. Avila”, L. FernBndez-Llebrez” and A. Linaresb ‘Perinatal Care Unit, Department of Obstetrics and Gvnecolopv University of the Pais V&o. Crucei Hospital, Vizcaya (Spa&j
and bDepartment
of Pediatrics.
Faculty of Medicine and Dentistry,
(Received July 26th, 1991) (Revised and accepted February 7th, 1992)
Abstract In order to evaluate the influence of mode of delivery on perinatal morbidity and mortality in vertex infants weighing less than 1500 g ( VLB W), we made a retrospective study of 152 singleton newborns, in vertex presentation, with a birthweight of less than 1500 g, delivered in the Cruces Hospital (Vizcaya, Spain), a major perinatal referral center, between 1 January 1987 and 31 December 1989. Twins and infants with lethal congenital anomalies or gross intrauterine growth deviations were excluded from the study (n = 71). Of the infants studied (n = 81), 37 were delivered by cesarean section (mean weight 1120 f 206 g, range: 680-1495 g) and 44 were delivered vaginally (mean weight 1029 f 283 g, range: 530- 14 75 g) , The patients were divided into four groups: Group A: 500-749 g (n = 10); Group B: 750-999 g (n = 21); Group C: 1000-1249 g (n = 27); and Group D: 1250-1499 g (n = 23). The percentages of cesarean sections in each group were IO%, 42%, 66% and 39”/0, respectively. A comparison within each group of immediate perinatal outcome (Apgar score and umbilical vein cord pH), as well as mortality and sequelae up to 1 year of age did not yield any significant differences between cesarean and vaginal birth. We conclude that cesarean 0020-7292/92/$05.00
0 1992 International Federation of Gynecology and Obstetrics Printed and Published in Ireland
delivery does not appear to offer improved outcome over vaginal delivery in live births without congenital anomalies. For this reason, we believe that fetal weight should not be the only obstetrical variable considered when deciding whether or not to perform a cesarean section in these circumstances.
Keywords: Prematurity;
Vertex presentation; Very low birthweight; Cesarean section; Vaginal delivery; Perinatal mortality.
Introduction
One of the great challenges in perinatology today is the management of low birthweight infants and, within this group, infants weighing less than 1500 g are usually described as very low birthweight (VLBW). During the 198Os, neonatal mortality rates dropped dramatically, largely due to the improved survival of low birthweight infants [5,9]. Probably the most influential factor has been the great advances made in neonatal intensive care [5,13]. However, this factor has created a series of clinical dilemmas regarding the management of these infants both before and during birth. The optimal mode of delivery for low birthArticle
182
Melchor et al
weight infants is a matter of great controversy. Based on the work of Goldenberg and Nelson [8] cesarean section is the proposed best mode of delivery to decrease perinatal morbidity and mortality, even in vertex births. This proposal is controversial. It is postulated that vaginal delivery is preferable in a vertex birth [3,15]. To study the influence of mode of delivery on vertex infants weighing less than 1500 g, tie studied immediate perinatal outcomes and both morbidity and mortality during the first year of life of these very low birthweight babies.
1000-1249 g (n = 27); and Group D: 1250-1499 g (n = 23). For the statistical analysis, the frequencies of the different variables were determined. Comparison between two qualitative variables was made using the chi-square test (with Yates’ correction when appropriate). The Student’s t-test was used to compare means and percentages and the Mann-Whitney test was employed when the distribution of cases did not follow a normal curve. Values of P < 0.05 were considered significant.
Materials and methods
The mean age of patients was 28.5 f 5.5 years. Forty-eight patients (59%) were primiparas. The mean gestational age at delivery was 28.2 * 2.7 weeks (23-33 weeks) and the mean birthweight was 1071 * 254 g. There were 42 males (51.85%) and 39 females. It was noted that only 26 of 81 patients received tocolytic agents (Ritodrine). Using the sonogram done shortly before delivery, 26.31% of the infants showed a discrepancy (1 l-2 weeks) between fetal biometry (sonographic age) and menstrual age. Except for 10 patients (12.34%), all other deliveries presented some type of perinatal risk in addition to the prematurity itself. The most frequent were premature rupture of membranes (PROM, 26 cases), hypertension of pregnancy (17 cases) and hemorrhage during the I-II trimester (8 cases) and during the III trimester (7 cases). Other, less frequent risks were oligohydramnios without PROM (3 cases), absence of prenatal care (3 cases),
A retrospective analysis was made of 152 singleton newborns with birthweights of less than 1500 g delivered at Cruces Hospital (Vizcaya, Spain), a major perinatal referral center between 1987 and 1989. Excluded from the study were twins (n = 36), stillborns (n = 23) and infants with lethal congenital anomalies (n = 7). Infants with a low birthweight for gestational age (intrauterine growth retardation) were also excluded (n = 5). A total of 19 090 deliveries were made during the study period. Antenatal steroids had not been used. The following factors were analyzed for the study: age, parity, course of gestation, gestational age, use or not of tocolytic drugs, agreement or disagreement with sonographic measurements, course of delivery, immediate perinatal outcomes (1-min and 5-min Apgar scores and umbilical vein cord pH), gender, mortality up to 1 year of age, causes of death, length of hospital stay of the newborn (in intensive care and total length of stay in the Pediatric Unit), as well as follow up of these infants (presence or absence of sequelae and type of same) during the first year of life. The study population was divided into four birthweight groups for the analysis of some variables: Group A: 500-749 g (n = 10); Group B: 750-999 g (n = 21); Group C:
Inr J Gynecol Obster 38
Results
Table 1. Mode of delivery (%) by birthweight groups.
500-749 g 750-999 g 1000-1249 g 1250-1499 g
Vaginal delivery (n=44)
Cesarean section (n = 37)
88.9 57.2 33.3 60.9
11.1 42.8 66.7 39.1
Perinatal outcome of very low birthweight infants by mode of delivery
183
Number of cases 124
750-999
grams
1000-1249 grams Birthweight groups
1250-1499
grams
Fig. 1. Indications for cesarean section by birtbweight groups.
polyhydramnios (I case) and maternal diabetes (1 case). Five patients presented other problems. Table 1 shows the mode of delivery in each of the birthweight groups. Particularly notable is the high frequency (66.66%) of cesarean sections in the birthweight group of lOOO-1249 g. The incidence of cesarean sections in the whole population was 45.67%. The most frequent indications for cesarean
Table 2.
section were hypertension (16 cases, 43.24%) and fetal distress (9 cases, 24.32%). Eight patients elected to have a cesarean delivery due to PROM, while the indication for the other four cases was III-trimester hemorrhage (2 for placenta previa and another 2 for placental abruption). Figure 1 presents a summary of the indications for cesarean delivery by birthweight groups. An analysis of immediate perinatal out-
Immediate perinatal outcomes (1’ and 5’ Apgar test and umbilical venous pH) by birthweight and mode of delivery. 750-999 g Cesarean section (n = 9)
1’Apgar c 4 37.5 5’ Apgar c 7 12.5 Umbilical pH < 7.20 25.0
1000-1249 g
1250-1499 g
Vaginal delivery (n = 12)
Cesarean section (n = 18)
Vaginal delivery (n = 9)
Cesarean section (n = 9)
Vaginal delivery (n = 14)
41.7 33.3 40.0
16.7 0 16.7
11.1 22.2 0
22.2 0 0
0 0 33.3
P values were not significant in any of the groups studied. (No comparison could be made in the birthweight group of 500-749 g since there was only one cesarean section in this group.)
Article
184
Melchor et al.
m
VAGINAL DELIVERY
=
CESAREAN
SECTION
66,6 /
/I
60
1000-1249
g.
t groups Fig. 2. Postneonatal mortality.
come (Table 2) do not show statistically significant differences in any of the groups studied, whether the delivery was made vaginally or abdominally. Postneonatal mortality (up to 1 year of age) is shown in Fig. 2. Mortality rates are very high under 1000 g (20/3 1 cases; 64.5 lo/), while above this weight, mortality was only 18.00% (9 cases). Of 29 infants who died before 1 year of age, 20 died during the first month of life. When we analyze mortality by birthweight groups and mode of delivery, we find no significant differences. The causes of death were: sepsis (3 cases); respiratory distress syndrome (RDS) (7 cases); sepsis + RDS (5 cases); RDS + intraventricular hemorrhage (IVH) (4 cases); sepsis + RDS + IVH (8 cases) and immaturite lungs development considered to be incompatible with extrauterine survival (2 cases). There Int J Gynecol Obstet 38
were no differences between vaginal and cesarean delivery (Table 3). Figure 3 summarizes the morbidity and type of sequelae presented by the infants who did not die during the first year of life Table 3. Causes (number) of death.
Sepsis RDS Sepsis + RDS RDS+ IVH Sepsis + RDS + IVH Inmaturity Other causes
Vaginal delivery (n=44)
Cesarean section (n = 37)
1 5 2 4
2 2 3 -
5 2
3 -
1
-
RDS, Respiratory Distress Syndrome; IVH, Intraventricular Hemorrhage. x2 = 6.73; P not significant (P = 0.34616).
Perinatal outcome of very low birthweight infants by mode of delivery
Number
185
of cases
-
VAGINAL DELIVERY
@@ CESAREAN
SECTION
6
NEUROLOGIC
NO Fig. 3.
RESPIRATORY
DIGESTIVE
MALFORMATIONS
Morbidity and type of sequelae.
100 80 60 40
SURVIVAL SEQUELAE
RATES RATES
(%I (%)
I
4
30
31
32
33
100
77,7
80
63,3
100
42,8
85,7
50
40
0
I
I
I
I
25
26
27
28
29
30
28,5
50
66,6
100
100
100
53,8 Week
-
Fig. 4.
I
I
0
SURVIVAL
I
of gestation
RATES (%I--
SEQUELAE
RATES (%I
Survival and sequelae rates (tendency) for each week of gestation. Article
186
Melchor et al.
(n = 51). No statistically significant differences were found. The sequelae were classified. as neurologic problems (cerebral palsy, hydrocephalus, and other forms of impairement), respiratory problems (bronchopulmonary dysplasia, respiratory distress syndrome), digestive problems (necrotizing enterocolitis, gastro-esophageal ebb), retinopathy and no lethal congenital malformations. Three newborns developed retinopathy and 8 newborns developed more than one sequela. Figure 4 presents the survival rates at 1 year of age and the percentage of short and longterm sequelae for each week of gestation. Note that survival goes up with increasing gestational age, while the index of sequelae, very high at 25-27 weeks, goes progressively down. Discussion The most notable aspect of this study is that, based on our results, it does not appear that cesarean section has a better outcome than vaginal delivery in vertex infants weighing less than 1500 g. We found no significant differences between the two modes of delivery in any of the parameters studied immediate perinatal outcome (Apgar score and umbilical vein cord pH), mortality up to 1 year of age, and existence of sequelae - for any of the four birthweight groups analyzed at 1 year of age. Other authors have found similar results [3,10,12,15]. Vaginal delivery is now the preferred method in the case of a vertex infant estimated to weigh less than 1500 g. In contrast to the studies cited, our population was pre-selected in that it excluded twins, infants with malformations and infants with a low or high birthweight for gestational age. This was done because the initial idea was to analyze the influence of delivery mode on morbidity and mortality. These results, however, should be viewed with caution since they pertain to a retrospective study and are, therefore, biased to some Int J Gynecol Obstet 38
extent. Practically all studies made on this subject suffer from the same problem. Furthermore, the results from different centers cannot always be extrapolated to others, as was shown by Fenton [6] in his prospective review of the management of premature infants of less than 33 weeks gestation in 17 centers in England. The perinatal factors that best predict survival in low birthweight infants are gestational age and birthweight [I 11, although in infants < 1000 g birthweight is clearly a more specific indicator than gestational age [I]. Antenatal determination of fetal weight and sonographic age based on ultrasonographic measurements have quite high rates of error. Unless the date of conception is known exactly, the calculation is only an estimate which has a variation of l-2 weeks, at best [2]. We found the discrepancy between sonographic age and menstrual age to be 26.31%. This discrepancy between fetal weight as estimated by ultrasound and birthweight makes it necessary for each work site to have its own weight curves. These graphs will be of enormous help in evaluating each case and deciding which mode of delivery will be most appropriate for the low birthweight infant. In our population, 500 g of weight are reached between 22 and 23 weeks of gestation. Therefore it is no longer acceptable to limit fetal viability to 25 weeks of gestation, especially when survivals have been described under that limit [8,16]. Furthermore, the underestimation of fetal weight is generally associated with high rates of perinatal mortality. For all these reasons, we believe that the attitude taken with respect to fetal viability is as important as birthweight. Obviously, ‘attitude’ alone cannot make a baby survive; however, attitude can allow for the proper perinatal measures to be taken in order to maximize the chance of survival. A greater or lesser interest in the infant during perinatal care will in large measure condition the neonatal outcome [2,6,9]. In addition to the weight chart, it is impor-
Perinatal outcome of very low birthweight
tant to have survival rates and the percentage of infants that present sequelae, for each week of gestation (Fig. 4). These, after all, are the data that will help us make decisions in the case of a low birthweight infant. Both neurological and other types of morbidity increase in frequency as gestational age at birth goes down. In Cooke’s [4] multicenter review of gestations under 28 weeks, he found a 20-50% rate of serious neurologic sequelae. Goldenberg [8] found similar rates. However these sequelae cannot be attributed exclusively to the mode of delivery. There are undoubtedly other factors that intervene in the genesis of these problems which are probably more important than the mode of delivery, such as perinatal asphyxia, respiratory distress, neonatal trauma, perinatal care, etc. [13]. Tejani [14] even suspected that intraventricular hemorrhage may be present before delivery and that this may bring on the premature birth. In our fmdings, of the 51 infants followed up to 1 year of age, 10 (19.60%) presented neurologic sequelae and live of these were delivered by cesarean section. In conclusion, our findings, with the limitations already mentioned, indicate that cesarean section does not offer an improved outcome over vaginal delivery in vertex infants weighing less than 1500 g. Nevertheless, we believe that the decision as to the optimal mode of delivery must be made individually in each case.
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Cooke RWI: Outcome and costs of care for the very immature infant. Br Med Bull 44: 1133, 1988 Ehrenhaft PM, Wagner JL, Herdman RC: Changing prognosis for very low birth weight infants. Obstet Gynecol 74: 528, 1989. Fenton A, Field DJ, Mason E, Clarke M: Attitudes to viability of preterm infants and their effect on figures for perinatal mortality. Br Med J 300: 434, 1990. Goldenberg RL, Nelson KG: The premature breech. Am J Obstet Gynecol 127: 240, 1977. Goldenberg RL, Nelson KG, Davis RO, Koski J: Delay in delivery: influence of gestational age and the duration of delay on perinatal outcome. Obstet Gynecol 64: 48C, 1984. Hack M, Fanaroff AA: Changes in the delivery room care of the extremely small infant (~750 g). Effects on morbidity and outcome. N Engl J Med 314: 660, 1986. Kitchen W, Ford GW, Doyle LW, Rickards AL, Lissenden JV, Pepperell RJ, Duke JE: Cesarean section or vaginal delivery at 24 to 28 weeks gestation: Comparison of survival and neonatal and 2-year morbidity. Obstet Gynecol 66: 149, 1985. Melchor JC, Femandez-Llebrez L, Linares A, Ariceta JM, Lopez JA, Rodriguez-Alar&n J, Corcostegui B, Aranguren G: Obstetrics variables predicting survival of immature newborn (< 1000 pm). Rev Esp Obst Ginec 2. 51, 1989. Olshan AF, Shy KK, Luthy DA, Hickok D, Weiss NS, Daling JR: Cesarean birth and neonatal mortality in very low birth weight infants. Obstet Gynecol 64: 267, 1984. Sachs BP, Ringer SA: Intrapartum and delivery room management of the very low birthweight infant. Clin Perinatol 16: 809, 1989. Tejani N, Verma U, Hameed C, Chayen B: Method and route of delivery in the low-birth-weight vertex presentation correlated with early periventricular/intraventricular hemorrhage. Obstet Gynecol 69: I, 1987. Welch RA, Bottoms SF: Reconsideration of head compression and intraventricular hemorrhage in the vertex very-low-birth-weight fetus. Obstet Gynecol 68: 29, 1986. Yu WYH, Loke HL, Bajuk B, Schymonowicz W, Orgill AA, Astbury J: Prognosis of infants born at 23 to 28 weeks’ gestation. Br Med J 293: 1200, 1986.
Address for reprints:
J.C. Mel&or Uaidad de Atencih Perinatal Hospital de Cruces Vizcaya, Spain
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