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Review of causes of perinatal mortality in a regional perinatal center, 1980 to 1984
Review of causes of perinatal mortality in a regional perinatal center, 1980 to 1984 Arne Ohlsson, M.D., Andrew T. Shennan, M.B., and Toby H. Rose, M.D. Toronto, Ontario, Canada During 1980 to 1984, 279 deaths occurred among 15,306 births in a regional perinatal unit. Survival to discharge corrected for lethal malformations was 81% or better in infants with a birth weight above 749 gm. Congenital malformations (23.2%), infections (21.3%), asphyxia (19.8%), and hyaline membrane disease (11 %) caused most perinatal deaths. (AM J OssTET GvNECOL 1987;157:443-5.)
Key words: Perinatal mortality review, congenital malformations, infections, neutropenia, neonate The purpose of this study was to review all perinatal deaths in a regional perinatal unit to indicate areas for improvements and research.
were reviewed. The ca.use of death was coded according to the International Classification of Diseases (lCD), 9th edition. The lCD code "extreme immaturity" was used only for appropriately grown neonates with a birth weight <600 gm, who died of a condition directly related to immaturity. "Definite infection" was defined as a clinical picture compatible with severe infection and growth of bacteria or virus in blood, cerebrospinal fluid, or tissue material at autopsy or a microscopic diagnosis of pneumonia. "Probable infection" was defined as a clinical picture compatible with serious infection, bacterial colonization, and neutropenia (mature neutrophils < 1300/mm') or leukocytosis (leukocytes >30,000/mm') and no other obvious causes of death. The occurrence of air leaks (pneumothorax, pneumomediastinum, pneumopericardium) and cardiac dysrythmias were noted in all neonatal deaths.
Material and methods
The Perinatal Unit at Women's College Hospital, Toronto, Ontario, Canada, serves both as a community hospital and as a level III perinatal facility for the Central East Region of Ontario, which has approximately 55,000 deliveries per year. Details of the perinatal management in the unit have been published previously.' All perinatal d€aths occurring in 15,306 in-hospital births of >20 weeks' gestation during 1980 to 1984
From the University of Toronto Regional Perinatal Unit and the Department of Pathology, Women's College Hospital. Received for publication November 24, 1986; revised January 20, 1987; accepted February 16, 1987. Reprint requests: Arne Ohlsson, M.D., Regional Perinatal Unit at Women's College Hospital, 76 Grenville St., Toronto, Ontario, Canada M5S 1B2.
Results
The birth weight distributions of live births, stillbirths, early neonatal deaths, late neonatal deaths, and
• =Hyaline membrane disease =Infection D =Asphyxia 18 =Necrotizing enterocolitis 1!1 = Intra ventricular haemorrhage B =Anemia gj
Gestation ( weeks) Fig. I. Distribution of possibly avoidable early neonatal deaths by gestational age (each square represents one death). (Forty-three neonates with lethal congenital malformations, 24 with birth weight <600 gm, five with an "oligohydramnios sequence," and four with severe nonimmune hydrops were excluded.)
443
444 Ohlsson, Shennan, and Rose
August 1987 Am J Obstet Gynecol
Table I. Perinatal mortality at Women's College Hospital, 1980 to 1984 Birth weight
Live births Stillbirths Total births Early neonatal deaths Late neonatal deaths Infant deaths First-week survival (%) Survival to discharget
,;;_499 gm
500-749 gm
750-999 gm
1000-1249 gm
1250-1499 gm
1500-1749 gm
7 3 10 7 (1) 0
109 19 (1 *) 128 49 (2) 6 3 55.1 47.7
184 10 (1) 194 33 (3) 2 4 (1) 82.1 81.7
212 7 219 20 (7) 5 (1) 1 90.6 88.2
220 7 (1) 227 11 (5) 1 3 (2)
215 7 (1) 222 8 (6) 1
95.0 96.2
96.3 98.6
0.0 0.0
*Figures in parentheses represent deaths from congenital malformations. tCorrected for lethal congenital malformations.
Table II. Cause of death (perinatal and infant deaths) Early neonatal deaths
Still births Cause
n
Congenital malformations Definite infections Probable infections Hyaline membrane disease Birth weight <600 gm (AGA) Asphyxia Intraventricular hemorrhage Oligohydramnios sequence Hydrops fetalis Other Unknown Sudden infant death Tracheal stenosis Bronchopulmonary dysplasia Total
11 17
I
%
n
12.9 20.0
43
38*
44.7
3 1 15
3.5 1.2 17.7
85
2~}
26 24 14 5 5 4 4
I
%
27.6 19.9 16.7 15.4 9.0 3.2 3.2 2.6 2.6
156
Late neonatal deaths n
7 8
I
%
31.8 36.4
3
13.6
4
18.2
22
Infant deaths n
7
1 1 7 16
I
%
43.8
6.3 6.3 43.8
*Abruptio placentae, n = 15; intrauterine growth retardation, n = 8; cord complication, n = 8; infant of diabetic mother, n = 1; other, n = 6.
infant deaths and the survival rates are shown in Table I. The first-week survival rate increased from 15.6% below 600 gm to 71.4% in the 600 to 749 gm weight group. The distribution of early neonatal deaths that possibly could have been avoided according to gestational age is shown in Fig. 1. Multiple birth was associated with 13.3% of all deaths. The main causes of perinatal deaths and infant deaths are shown in Table II. The autopsy rate was 70%. Thirty-eight percent of the stillbirths occurred in hospitalized mothers. Air leaks occurred in 25.3% of the neonatal deaths. Renal failure causing hyperkalemia and cardiac tachydysrythmias occurred in 12.4% of early neonatal deaths < 1000 gm. Early neonatal deaths from infections were associated with premature rupture of the membranes for >24 hours in 39% and infection in 67% of the mothers. Seventy-seven percent of the early neonatal deaths that were due to a definite infection involved
neutropenia. Gram-negative bacteria were most commonly isolated (34%). Comment
Prevention of preterm birth and low birth weight remains the major challenge in reproductive medicine today as mortality is closely linked to immaturity and low birth weight (Table I, Fig. 1). Multiple births carry a high risk of perinatal death. Events such as intraventricular hemorrhage, air leaks, and dysrythmias secondary to hyperkalemia often precede death in critically sick neonates. The major cause of perinatal death was congenital malformation (23.2%). Many of these anomalies were detected antenatally, but very few conditions were potentially amenable to fetal operations. Elective abortion after early antenatal diagnosis is presently the only available approach to decrease this major cause of mor-
Perinatal mortality review
Volume 157 Number 2
445
Birth weight 1750-1999 gm
2000-2249 gm
2250-2499 gm
2500+ gm
Total
220 1 (1) 221 2 (2)
272 4 (1) 276 lO (9)
345 6 (1) 351 1 2 (1) 1 (1)
13,437 21 (4) 13,458 15 (8) 5 (5)
15,221 85 15,306 156 22 16
99.1
96.3
99.7
99.9
99.5
99.6
99.9
99.9
4 (3)
tality. Routine use of ultrasonography at 17 and 33 weeks' gestation in all pregnant women• detects not only congenital anomalies but also other conditions associated with perinatal death such as multiple births and growth retardation. It has been argued that with the advent of intensive care, perinatal mortality has been improved by moving inevitable deaths into the infant age group. In this study only 6% of the deaths occurred between 28 days of life and discharge to home, and the survival rates to discharge were minimally affected by late neonatal deaths or infant deaths (Table 1). Given a birth weight of >749 gm and no congenital malformations the chance of survival to discharge to home was 81% or better. The second most common cause of perinatal death was infection (21.3%). Neutropenia, known to be associated with poor outcome, occurred in 77% of the early neonatal deaths that were due to a definite infection. The incidence of maternal infection that was undetected prior to delivery was high in this group. Tests used so far to detect infectious morbidity in mothers with premature rupture ofthe membranes lack both sensitivity and specificity. Hyaline membrane disease, infection, and asphyxia were the main, possibly preventable deaths (Fig. 1). Only one neonate born after 28 weeks' gestation died of hyaline membrane disease, but 10 died of infection. However, hyaline membrane disease remained the rna-
jor cause of possibly preventable neonatal death at gestational ages below this (Fig. 1). Hyaline membrane disease also caused late neonatal deaths and was the initial diagnosis in seven infant deaths that were due to bronchopulmonary dysplasia and in one infant death due to tracheal stenosis. Bronchopulmonary dysplasia was the major cause of possibly preventable infant deaths. This study represents a selected high-risk population of pregnant mothers admitted to a regional perinatal unit and should be complemented by an audit of all perinatal deaths in the geographic region served by the unit. Such an audit should also consider sociodemographic factors influencing pregnancy outcome. Randomized controlled studies are needed to determine the effectiveness of new interventions to prevent and/or treat preterm delivery, premature rupture of the membranes, low birth weight, maternal-fetal bacterial infections, hyaline membrane disease, and hyperkalemia. REFERENCES l. Milligan JE, Shennan AT. Perinatal management and out-
come in the infant weighing 1000 to 2000 grams. AM J 0BSTET GYNECOL 1980;136:269-75. 2. Persson P-H, Kullander S. Long-term experience of general ultrasound screening in pregnancy. AM J OBSTET GYNECOL 1983;146:942-7.
Key words: Perinatal mortality review, congenital malformations, infections, neutropenia, neonate The purpose of this study was to review all perinatal deaths in a regional perinatal unit to indicate areas for improvements and research.
were reviewed. The ca.use of death was coded according to the International Classification of Diseases (lCD), 9th edition. The lCD code "extreme immaturity" was used only for appropriately grown neonates with a birth weight <600 gm, who died of a condition directly related to immaturity. "Definite infection" was defined as a clinical picture compatible with severe infection and growth of bacteria or virus in blood, cerebrospinal fluid, or tissue material at autopsy or a microscopic diagnosis of pneumonia. "Probable infection" was defined as a clinical picture compatible with serious infection, bacterial colonization, and neutropenia (mature neutrophils < 1300/mm') or leukocytosis (leukocytes >30,000/mm') and no other obvious causes of death. The occurrence of air leaks (pneumothorax, pneumomediastinum, pneumopericardium) and cardiac dysrythmias were noted in all neonatal deaths.
Material and methods
The Perinatal Unit at Women's College Hospital, Toronto, Ontario, Canada, serves both as a community hospital and as a level III perinatal facility for the Central East Region of Ontario, which has approximately 55,000 deliveries per year. Details of the perinatal management in the unit have been published previously.' All perinatal d€aths occurring in 15,306 in-hospital births of >20 weeks' gestation during 1980 to 1984
From the University of Toronto Regional Perinatal Unit and the Department of Pathology, Women's College Hospital. Received for publication November 24, 1986; revised January 20, 1987; accepted February 16, 1987. Reprint requests: Arne Ohlsson, M.D., Regional Perinatal Unit at Women's College Hospital, 76 Grenville St., Toronto, Ontario, Canada M5S 1B2.
Results
The birth weight distributions of live births, stillbirths, early neonatal deaths, late neonatal deaths, and
• =Hyaline membrane disease =Infection D =Asphyxia 18 =Necrotizing enterocolitis 1!1 = Intra ventricular haemorrhage B =Anemia gj
Gestation ( weeks) Fig. I. Distribution of possibly avoidable early neonatal deaths by gestational age (each square represents one death). (Forty-three neonates with lethal congenital malformations, 24 with birth weight <600 gm, five with an "oligohydramnios sequence," and four with severe nonimmune hydrops were excluded.)
443
444 Ohlsson, Shennan, and Rose
August 1987 Am J Obstet Gynecol
Table I. Perinatal mortality at Women's College Hospital, 1980 to 1984 Birth weight
Live births Stillbirths Total births Early neonatal deaths Late neonatal deaths Infant deaths First-week survival (%) Survival to discharget
,;;_499 gm
500-749 gm
750-999 gm
1000-1249 gm
1250-1499 gm
1500-1749 gm
7 3 10 7 (1) 0
109 19 (1 *) 128 49 (2) 6 3 55.1 47.7
184 10 (1) 194 33 (3) 2 4 (1) 82.1 81.7
212 7 219 20 (7) 5 (1) 1 90.6 88.2
220 7 (1) 227 11 (5) 1 3 (2)
215 7 (1) 222 8 (6) 1
95.0 96.2
96.3 98.6
0.0 0.0
*Figures in parentheses represent deaths from congenital malformations. tCorrected for lethal congenital malformations.
Table II. Cause of death (perinatal and infant deaths) Early neonatal deaths
Still births Cause
n
Congenital malformations Definite infections Probable infections Hyaline membrane disease Birth weight <600 gm (AGA) Asphyxia Intraventricular hemorrhage Oligohydramnios sequence Hydrops fetalis Other Unknown Sudden infant death Tracheal stenosis Bronchopulmonary dysplasia Total
11 17
I
%
n
12.9 20.0
43
38*
44.7
3 1 15
3.5 1.2 17.7
85
2~}
26 24 14 5 5 4 4
I
%
27.6 19.9 16.7 15.4 9.0 3.2 3.2 2.6 2.6
156
Late neonatal deaths n
7 8
I
%
31.8 36.4
3
13.6
4
18.2
22
Infant deaths n
7
1 1 7 16
I
%
43.8
6.3 6.3 43.8
*Abruptio placentae, n = 15; intrauterine growth retardation, n = 8; cord complication, n = 8; infant of diabetic mother, n = 1; other, n = 6.
infant deaths and the survival rates are shown in Table I. The first-week survival rate increased from 15.6% below 600 gm to 71.4% in the 600 to 749 gm weight group. The distribution of early neonatal deaths that possibly could have been avoided according to gestational age is shown in Fig. 1. Multiple birth was associated with 13.3% of all deaths. The main causes of perinatal deaths and infant deaths are shown in Table II. The autopsy rate was 70%. Thirty-eight percent of the stillbirths occurred in hospitalized mothers. Air leaks occurred in 25.3% of the neonatal deaths. Renal failure causing hyperkalemia and cardiac tachydysrythmias occurred in 12.4% of early neonatal deaths < 1000 gm. Early neonatal deaths from infections were associated with premature rupture of the membranes for >24 hours in 39% and infection in 67% of the mothers. Seventy-seven percent of the early neonatal deaths that were due to a definite infection involved
neutropenia. Gram-negative bacteria were most commonly isolated (34%). Comment
Prevention of preterm birth and low birth weight remains the major challenge in reproductive medicine today as mortality is closely linked to immaturity and low birth weight (Table I, Fig. 1). Multiple births carry a high risk of perinatal death. Events such as intraventricular hemorrhage, air leaks, and dysrythmias secondary to hyperkalemia often precede death in critically sick neonates. The major cause of perinatal death was congenital malformation (23.2%). Many of these anomalies were detected antenatally, but very few conditions were potentially amenable to fetal operations. Elective abortion after early antenatal diagnosis is presently the only available approach to decrease this major cause of mor-
Perinatal mortality review
Volume 157 Number 2
445
Birth weight 1750-1999 gm
2000-2249 gm
2250-2499 gm
2500+ gm
Total
220 1 (1) 221 2 (2)
272 4 (1) 276 lO (9)
345 6 (1) 351 1 2 (1) 1 (1)
13,437 21 (4) 13,458 15 (8) 5 (5)
15,221 85 15,306 156 22 16
99.1
96.3
99.7
99.9
99.5
99.6
99.9
99.9
4 (3)
tality. Routine use of ultrasonography at 17 and 33 weeks' gestation in all pregnant women• detects not only congenital anomalies but also other conditions associated with perinatal death such as multiple births and growth retardation. It has been argued that with the advent of intensive care, perinatal mortality has been improved by moving inevitable deaths into the infant age group. In this study only 6% of the deaths occurred between 28 days of life and discharge to home, and the survival rates to discharge were minimally affected by late neonatal deaths or infant deaths (Table 1). Given a birth weight of >749 gm and no congenital malformations the chance of survival to discharge to home was 81% or better. The second most common cause of perinatal death was infection (21.3%). Neutropenia, known to be associated with poor outcome, occurred in 77% of the early neonatal deaths that were due to a definite infection. The incidence of maternal infection that was undetected prior to delivery was high in this group. Tests used so far to detect infectious morbidity in mothers with premature rupture ofthe membranes lack both sensitivity and specificity. Hyaline membrane disease, infection, and asphyxia were the main, possibly preventable deaths (Fig. 1). Only one neonate born after 28 weeks' gestation died of hyaline membrane disease, but 10 died of infection. However, hyaline membrane disease remained the rna-
jor cause of possibly preventable neonatal death at gestational ages below this (Fig. 1). Hyaline membrane disease also caused late neonatal deaths and was the initial diagnosis in seven infant deaths that were due to bronchopulmonary dysplasia and in one infant death due to tracheal stenosis. Bronchopulmonary dysplasia was the major cause of possibly preventable infant deaths. This study represents a selected high-risk population of pregnant mothers admitted to a regional perinatal unit and should be complemented by an audit of all perinatal deaths in the geographic region served by the unit. Such an audit should also consider sociodemographic factors influencing pregnancy outcome. Randomized controlled studies are needed to determine the effectiveness of new interventions to prevent and/or treat preterm delivery, premature rupture of the membranes, low birth weight, maternal-fetal bacterial infections, hyaline membrane disease, and hyperkalemia. REFERENCES l. Milligan JE, Shennan AT. Perinatal management and out-
come in the infant weighing 1000 to 2000 grams. AM J 0BSTET GYNECOL 1980;136:269-75. 2. Persson P-H, Kullander S. Long-term experience of general ultrasound screening in pregnancy. AM J OBSTET GYNECOL 1983;146:942-7.