Fræðigrein

Objective: Survival of extremely low birthweight infants with birthweight <1000 g (ELBW) has increased in recent years, parallel to decline in perinatal mortality rate. This study was part of a geographically defined national study on survival, health, development and longterm outcome of ELBW infants in Iceland 1991-95 focusing on infant and maternal health risk factors affecting infant survival.

Material and methods: Information was collected from the National Birth Registry on births and survival of ELBW infants weighing 500-999 g born in Iceland 1991-95. Information was obtained from hospital records of all liveborn ELBW infants and their mothers regarding maternal health, pregnancy, birth, diseases in the newborn period, lifespan and causes of death. Information on causes of death was collected from autopsy records of deceased infants. Comparison was made between the deceased ELBW infants and the control infants that survived.

Results: The study group consisted of 28 infants that died and a control group of 32 infants that survived. Most of the infants died in the first 24 hours after birth (47%). There was no significant difference in birthweight in the two groups nor regarding age of mothers, smoking, alcohol use and medication. Nearly all mothers of deceased infants (97%) had health problems during the pregnancy, compared to 66% mothers in the control group. Mothers of deceased infants had significantly more common infections (p=0.004). Significant difference was found regarding respiratory distress syndrome and intraventricular hemorrhage in infants that died (p=0.001).

Conclusions: The results of the study support that short pregnancy, infection during pregnancy and intraventricular hemorrhage were the main risk factors causing death of ELBW infants in the perinatal and neonatal period in 1991-95.

 

 

Table I.           Birth Statistics and Survival of Children with

Birthweight 500-999g born in Iceland 1991-95

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Registered births 500-999g                               102 (0.5%)         

Liveborn                                                             67

Stillborn                                                              35

Long Term Survivors                                          35 (52%)

Diseased Infants                                                 32 (48%)

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Girls                                                                   58 (57%)

Boys                                                                  44 (43%)

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Table II.          Time of Death of Children with Birthweight

500-999g born in Iceland 1991-95.

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                                      n                      (%)

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Died on Day 1              16                      (57)

Died on Day 2-7            4                      (14)

Late Deaths                    8                      (29)

 

Total                            28                    (100)

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Table III.        Birthweight Groups of Diseased Children

and Survivors with Birthweight 500-999g.

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                                     Diseased                     Survivors         

                                    n          (%)                  n         (%)

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500-599g                     5          (18)                    1          (3)

600-699g                     6          (21)                    3          (9)

700-799g                     3          (11)                    5        (16)

800-899g                     6          (21)                  15        (47)

900-999g                     8          (29)                    8        (25)

Total                          28        (100)                  32      (100)

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SGA*                        14          (50)                  14        (44)

Multiple births               6          (21)                    4        (12,5)

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*SGA=Small for gestational age

 

Table IV.        Clinical Data on Maternal Health during Pregnancy and Delivery.

Comparison of  Mothers of Diseased Children and Survivors with Birthweight 500-999g.

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                                    Diseased ELBW*                     ELBW* Survivors       

                                    mean    M**   range                 mean   M**  range      p

 

Maternal age in years      29      30    (16-43)                30        31   (19-39)     NS

Gestation weeks             26      25    (22-36)                27        27   (24-32)     NS***

Birthweight in grams      768    767   (559-999)             834    840  (590-990)  NS

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                                     n         (%)                              n         (%)                  p

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Smoking                       10        (36)                              14        (44)                  NS

Alcohol use                    1          (4)                                0          (0)                  NS

Medication use   5        (18)                                7        (22)                  NS

 

All Diseases                  27        (96)                              21        (66)                  NS

Antepartum Hem.         15        (54)                              12        (34)                  NS

Infection                       13        (46)                                4        (13)                  0.004

Hypertension                  4        (14)                                8        (23)                  NS

Other                             8        (29)                                6        (26)                  NS

 

Cesarian Section           10        (36)                              18        (56)                  NS

Vaginal birth                 18        (64)                              32        (44)                  NS

 

Total                            28      (100)                              32      (100)

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*ELBW=Extremely Low Birthweight = Birthweight < 1000g

**M=Median Value

*** p=0.03 for Median Value of Gestation Weeks

 

 

 

Table V.          Clinical Data and Comparison of Diseased Children

and Survivors with Birthweight 500-999g.

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    Diseased ELBW*            ELBW* Survivors

                                                             n         (%)                   n         (%)                  p

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Respiratory Distress Syndrome 16        (57)                  31        (97)            <0.001

Patent Ductus Arteriosus                         7        (25)                  13        (41)                  NS

Infections                                              12        (43)                  18        (56)                  NS

Necrotizing Enterocolitis                         2          (7)                    1          (3)                  NS

Congenital Anomalies                            1          (4)                    0          (0)                  NS

CNS** infection                                    0         (0)                    2          (6)                  NS

Intraventicular hemorrhage                    14        (50)                    2          (6)            <0.001

Total                                                    28      (100)                  32      (100)___________

*ELBW=Extremely Low Birthweight = Birthweight < 1000g

**CNS=Central Nervous System

 

Table VI.        Cause of Death of ELBW* children 1991-1995

determined by Obduction.

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Intraventricular Hemorrhage                    8        (33)

Immaturitas                                             7        (29)

Broncopulmonary Dysplasia                    3        (12,5)

Infection                                                 3        (12,5)

Respiratory Distress Syndrome   1          (4)

Congenital Anomalies                             1          (4)

Other                                                     1          (4)

Total                                                    24      (100)___________

*ELBW=Extremely Low Birthweight = Birthweight < 1000g