High Risk Of Perinatal Death Research Articles

Factors Affecting Short-Term Mortality in Very Low Birth Weight Infants in Japan

No epidemiological surveys have examined risk factors related to the death of very low birth weight infants (VLBWIs) in Japan. The objectives of this study were to examine the death rate and fatalities related to complications among VLBWIs, and to analyze factors possibly determining the death of VLBWIs. The subjects of this study were 811 VLBWIs admitted to the Neonatal Care Center of Niigata City General Hospital between April 1987 and March 2003. We obtained information on gender, birth weight, gestational age, Apgar scores, single/multiple pregnancy, postnatal transfer, mode of delivery, complications and outcome (alive or deceased) at the time of discharge from medical records. Of the 811 infants, 98 died prior to discharge (12.1%). Logistic regression analysis showed that independent risk factors for death of VLBWIs were male gender (relative risk [RR]: 2.0), low birth weight (RR: 0.56), necrotizing enterocolitis (RR: 58.0), pulmonary hypoplasia (RR: 37.8), chromosomal abnormalities (RR: 36.3), congenital heart diseases (RR: 9.8), persistent fetal circulation (RR: 9.6), neonatal asphyxia (RR: 6.3) and sepsis (RR: 4.4). The risk for death rises 1.8-fold if birth weight decreases by 100 g. A very high risk of perinatal death is associated with necrotizing enterocolitis, pulmonary hypoplasia or chromosomal abnormalities. The risk of death due to congenital heart diseases or neonatal asphyxia is relatively lower, but the incidences of these two disorders are high (8% and 6%, respectively). From the viewpoint of prophylactic treatment aimed at reducing the death rate of VLBWIs, measures to increase birth weight are of primary importance. Furthermore, early treatment and improved perinatal management of congenital heart diseases and neonatal asphyxia are anticipated to reduce the overall death rate of VLBWIs.

Placental abruption and perinatal mortality in the United States.

Placental abruption is an uncommon obstetric complication associated with high perinatal mortality rates. The authors explored the associations of abruption with fetal growth restriction, preterm delivery, and perinatal survival. The study was based on 7,508,655 singleton births delivered in 1995 and 1996 in the United States. Abruption was recorded in 6.5 per 1,000 births. Perinatal mortality was 119 per 1,000 births with abruption compared with 8.2 per 1,000 among all other births. The high mortality with abruption was due, in part, to its strong association with preterm delivery; 55% of the excess perinatal deaths with abruption were due to early delivery. Furthermore, babies in the lowest centile of weight (<1% adjusted for gestational age) were almost nine times as likely to be born with abruption than those in the heaviest (> or =90%) birth weight centiles. This relative risk progressively declined with higher birth weight centiles. After controlling for fetal growth restriction and early delivery, the high risk of perinatal death associated with abruption persisted. Even babies born at 40 weeks of gestation and birth weight of 3,500-3,999 g (where mortality was lowest) had a 25-fold higher mortality with abruption. The link between fetal growth restriction and abruption suggests that the origins of abruption lie at least in midpregnancy and perhaps even earlier.

Infants' length at birth: an independent effect on perinatal mortality

To investigate whether variations in birth length (crown-heel-length) were associated with perinatal mortality rate independent of birth weight. The study population was singleton live- and stillbirths from 16 weeks of gestation compiled in the Medical Birth Registry of Norway from 1967 to 1997, totaling 1,705,652 births. The total population was analyzed using z-scores for length at birth, birth weight and gestational age. Variation in perinatal mortality by length at birth was studied within birth weight strata (250 g) by logistic regression. Perinatal mortality varied more by birth length than by birth weight or gestational age, especially for values above the population means. Within birth weight strata, the association between perinatal mortality and length was similar in all 250 g birth weight categories above 1,500 grams: mortality was lowest at birth lengths 0-2 cm below average, with mortality rates increasing exponentially in either direction. Within all birth weight strata, and adjusted for gestational age, long infants had the higher risk of perinatal death, suggesting that length at birth may be a valuable predictor when assessing the risk of perinatal mortality.

Birth-Weight-Specific Perinatal Mortality in Japan, 1989–1993: Singleton versus Multifetal Pregnancies

Objective: To investigate the relation between birth weight and perinatal mortality in multifetal pregnancies, which is more than 5 times higher than for singleton infants. Methods: We assessed the incidence of perinatal deaths based on birth weight in 89,566 infants of multifetal pregnancies and 6,025,199 infants of singleton pregnancies in Japan. Perinatal death was defined as stillbirth and early neonatal death (death <1 week of age). Results: The incidence of perinatal death was consistently lower for infants of multifetal pregnancies than for infants of singleton pregnancies at birth weights of 500–2,499 g. However, the incidence of infants of multifetal pregnancies with birth weights ≥2,500 g consistently exceeded that in singleton infants weighing ≥2,500 g. The relative risk (95% CI) of perinatal death among infants of multifetal pregnancies compared with singleton infants in the same category of birth weight was 0.88 (0.84–0.93) at 500 g. The relative risk decreased to 0.31 (0.25–0.39) at 1,900 g, increased to >1.0 at 2,500 g, to 3.7 (2.2–6.1) at 3,000 g, and to 14.9 (7.8–28.4) at ≥3,500 g. Conclusions: Japanese infants of multifetal pregnancies reaching ≥2,500 g in body weight have a significantly higher risk of perinatal death than singleton infants in the same category of body weight. Increased monitoring of fetuses of multifetal pregnancies who weigh ≥2,500 g may be helpful in reducing the incidence of perinatal mortality.

Pathological basis for abnormal umbilical artery doppler waveforms in pregnancies complicated by intrauterine growth restriction: A review

Summary The abnormal umbilical artery Doppler waveform represented by absent enddiastolic flow velocity (AEDFC) identifies a group of preterm fetuses with intrauterine growth restriction (IUGR) at high risk of perinatal death due chronic hypoxia from compromised umbilical artery blood flow. Initial studies of AEDFV placentae suggested a loss of small stem arterioles, though by immunohistochemical localization with an antibody to α-smooth muscle actin, we were unable to demonstrate any selective loss of even the smallest vessels in the 10–25 μM post-fixation diameter range. Further studies of villous ultrastructure and immunohistochemical localization of matrix molecules (laminin and collagens I, III and IV) demonstrated evidence of villous fibrosis and trophoblast aging. Parallel scanning electron microscopy studies demonstrated reduced numbers of malformed peripheral villi, whose capillaries were elongated and only poorly branched. Several of the structural differences in the terminal villi of this IUGR group, such as reduced cytotrophoblast proliferation and stromal fibrosis, are incompatible with the prevailing view of placental hypoxia in preterm IUGR with AEDFV. Reduced numbers of malformed terminal vili would be predicted to both increase capillary vascular impedance, and compromise placental gas exchange. Despite the known reduction in uteroplacental arterial blood flow in IUGR with AEDFV in the umbilical arteries, there is a greater fall in extraction of oxygen from the intervillous space: as such that maternal blood leaving the placenta has a higher content than under normal circumstances. Our data challenge the presumption of “placental hypoxia” in this subset of preterm IUGR pregnancies complicated by AEDFV in the umbilical arteries, which has both scientific and clinical implications.

Structural analysis of placental terminal villi from growth-restricted pregnancies with abnormal umbilical artery doppler waveforms

The abnormal umbilical artery Doppler waveform represented by absent end-diastolic flow velocity (AEDFV) identifies a group of preterm small-for-gestational age fetuses that are at high risk of perinatal death due to chronic fetal hypoxia. The placental ischaemia that results from inadequate trophoblast invasion of spiral arterioles leads to an assumption of placental villous hypoxia, though an alternative explanation is that the placenta fails to adequately transfer oxygen to the fetus from the intervillous space. Because oxygen transport takes place within the terminal villi, we undertook the first detailed studies of villous ultrastructure structure and immunohistochemistry in order to determine the likely origin of fetal hypoxia in this condition. Terminal villi were examined ultrastructurally using transmission electron microscopy and by immunohistochemical localization of matrix molecules (laminin and collagens I, III and IV) and a marker of cell proliferation (MIB-1), in 16 small-for-gestational age pregnancies with AEDFV in the umbilical artery [deemed to have intrauterine growth restriction (IUGR)] and in 16 gestation age-matched controls. Terminal villi from the IUGR cases were smaller in diameter (P < 0.02) and had several abnormal features in comparison with the controls; increased syncytial nuclei (P < 0.01), reduced cytotrophoblast nuclei (P < 0.01), thickened basal lamina (P < 0.01), and increased stromal deposition of collagens and laminin. The amount of proliferating cytotrophoblast was reduced in the IUGR group (P < 0.014) and the degree of capillary erythrocyte congestion within terminal villous capillaries was increased (P < 0.001). Several of the structural differences in the terminal villi of the IUGR group such as reduced cytotrophoblast proliferation and stromal fibrosis are incompatible with the prevailing view of placental hypoxia in IUGR. Rather thickening of the basal lamina and congestion of the capillaries by erythrocytes are predicted to limit oxygen transfer from the intervillous space to the fetus and may represent an equilibration of oxygen tension between intervillous space and the terminal villi. Despite the known reduction in uteroplacental blood flow in IUGR, fetoplacental blood flow is compromised to a far greater extent in the presence of AEDFV such that maternal blood leaving the placenta has a higher oxygen content than under normal circumstances.

Preliminary Experience With Endoscopic Laser Surgery for Severe Twin-Twin Transfusion Syndrome

Background In monozygotic twin pregnancies, there are placental vascular communications between the two fetuses. In 15 percent of such pregnancies there is an imbalance in net blood flow between the twins, resulting in the twin–twin transfusion syndrome. The recipient twin may have severe hydramnios during the second trimester of pregnancy, and there is a high risk of perinatal death and cerebral palsy in survivors. This condition can now be treated by endoscopic coagulation of the vascular anastomoses responsible for fetofetal transfusion with a neodymium:yttrium–aluminum–garnet (Nd:YAG) laser. Methods We performed intrauterine surgery in 45 pregnant women carrying twins at 15 to 28 weeks of gestation (median, 21); in each case there was severe hydramnios in one fetus due to the twin–twin transfusion syndrome. With the use of local anesthesia and continuous ultrasound visualization, a rigid fetoscope 2 mm in diameter, housed in a 2.7-mm cannula, was introduced transabdominally into the amniotic cavity of...

Preliminary experience with endoscopic laser surgery for severe twin-twin transfusion syndrome.

In monozygotic twin pregnancies, there are placental vascular communications between the two fetuses. In 15 percent of such pregnancies there is an imbalance in net blood flow between the twins, resulting in the twin-twin transfusion syndrome. The recipient twin may have severe hydramnios during the second trimester of pregnancy, and there is a high risk of perinatal death and cerebral palsy in survivors. This condition can now be treated by endoscopic coagulation of the vascular anastomoses responsible for fetofetal transfusion with a neodymium:yttrium-aluminum-garnet (Nd: YAG) laser. We performed intrauterine surgery in 45 pregnant women carrying twins at 15 to 28 weeks of gestation (median, 21); in each case there was severe hydramnios in one fetus due to the twin-twin transfusion syndrome. With the use of local anesthesia and continuous ultrasound visualization, a rigid fetoscope 2 mm in diameter, housed in a 2.7-mm cannula, was introduced transabdominally into the amniotic cavity of the recipient twin. A systematic search was made for all vessels approaching or crossing the membrane between the twins, and these were coagulated with an Nd:YAG laser by means of a fiber in the side arm of the cannula. Coagulation of the communicating vessels was successful in all cases. The total number of fetuses who survived to delivery was 48 (53 percent), and the number of pregnancies with at least 1 survivor was 32 (71 percent). Among the live-born infants, the median gestational age at delivery was 35 weeks (range, 25 to 40), and the median birth weight was 2098 g (range, 550 to 4252). The median interval between the endoscopic laser procedure and delivery was 14 weeks (range, 0 to 21). All the survivors were developing normally at a median age of 12 months (range, 2 to 24). Our preliminary experience suggests that the twin-twin transfusion syndrome can be treated effectively by endoscopic laser coagulation of the communicating placental vessels.

Endoscopic laser coagulation of umbilical cord vessels in twin reversed arterial perfusion sequence.

In monozygotic twin pregnancies with reversed arterial perfusion (TRAP) sequence, the donor twin is ut high risk of perinatal death. This paper describes the use of endoscopic surgery in the management of this condition. In four cases of TRAP sequence presenting at 17, 20, 26 and 28 weeks' gestation, respectively, an endoscope was introduced into the uterus under local anesthesia and a Nd-YAG laser was used to coagulate the umbilical cord vessels of the acardiac twin. Laser coagulation was successful in arresting blood flow to the acardiac fetus in the cases treated at 17 and 20 weeks, and healthy infants were delivered at term. In the pregnancies treated at 26 and 28 weeks, the umbilical cords were very edematous and laser coagulation failed to arrest blood flow; healthy infants were delivered after spontaneous labor at 29 weeks. These findings suggest that, during mid-gestation, endoscopic laser coagulation of the umbilical cord vessels of the acardiac twin is an effective method of treating TRAP sequence. In later pregnancy, alternative methods of treatment are needed.

Birthweight-specific trends in perinatal mortality by hospital category in South Australia, 1985-1990.

To investigate differences by birthweight in risk of perinatal death between level 3 hospitals (which provide care for high risk pregnancies and neonatal intensive care) and other hospitals in South Australia, using perinatal data for the 1985-1990 period. Analysis of birthweight-specific trends in risk of perinatal death by hospital category for singleton births, adjusting for risk factors. 114 725 singleton births of at least 400 g birthweight (or at least 20 weeks' gestation) born in hospitals in the 1985-1990 period and notified to the perinatal data collection. The relative odds of a perinatal death, as opposed to a live birth which survived the neonatal period. Births at level 3 hospitals had a higher crude risk of perinatal death than those at other hospitals, but this was due to the higher frequency of low birthweights at level 3 hospitals. For birthweights under 2000 g, and especially for the very low birth-weights, there was a higher risk at non-level-3 than level 3 hospitals. There was also the unexpected finding that births at level 3 hospitals in the 2500-2999 g range had a comparatively high risk of perinatal death. There was little difference in risk for births of higher birthweight. The greatly reduced risk of perinatal death in level 3 hospitals for babies with birthweights under 2000 g seems likely to be due to the specialist services in these hospitals. Further investigation is required to determine why babies in the 2500-2999 g range of birthweights had a comparatively high risk of perinatal death at these hospitals. This appears to be due, at least in part, to an excess contribution of deaths from congenital abnormalities. Also, it seems that the higher prevalence of complications in pregnancy in level 3 hospitals, and the transfers for induction of labour after intrauterine fetal death, would have made a contribution. These same factors may also have affected the risk in level 3 hospitals for higher birthweight births.

Perinatal Mortality in Shanghai: 1986–1987

The incidence of, and risk factors associated with, perinatal mortality in Shanghai during 1986-1987 are examined using data from a multi-site study conducted in 29 hospitals. The overall perinatal mortality rate was 14.96 per 1000 births. The mortality rates of antepartum fetal death, intrapartum fetal death and early neonatal death were 5.97, 2.06 and 6.94 per 1000 births, respectively. The perinatal mortality rates increased in winter and late spring. Male neonates were 1.5 times more likely to die than females. Low birthweight and preterm infants had 15 to 80 times higher risk of perinatal death. Higher parity, multiple pregnancy, and maternal age greater than or equal to 35 years were the risk factors for perinatal mortality. Asphyxia, cord complications, and congenital malformations were found to be the major causes of perinatal deaths. Comparison of mortality rates between Shanghai and the US suggests that the shortage of advanced technology in perinatal care (e.g. neonatal intensive care units) is a major obstacle to the reduction of perinatal mortality in Shanghai.

Maternal serum-alpha-fetoprotein and low birth-weight.

High maternal serum-alpha-fetoprotein (A.F.P.) concentrations in the first half of pregnancy were associated with prematurity and high perinatal mortality. 94 singleton pregnancies without neural-tube defects but with A.F.P. levels equal to or greater than three times the normal median resulted in the birth of infants weighing, on average, 357 g less than controls (P less than 0-001). The mean head circumference of the infants was also smaller than that of the controls. The 1 stillbirth and 3 neonatal deaths yielded a mortality-rate more than three and a half times that for singleton births without neural-tube defects at the same hospital in the years 1974-76. The results suggest that some pregnant women who will deliver low-birth-weight infants at high risk of perinatal death may be identified by means of serum-A.F.P. measurement early in pregnancy.