Effects of birth order, gender, and intrauterine growth retardation on the outcome of very low birth weight in twins

Illness severity measured by CRIB score: a product of changes in perinatal care?

AIM

To determine the perinatal factors associated with initial illness severity (measured by the CRIB (clinical risk index for babies) score) and its relation to survival to discharge.

METHODS

A retrospective study was made of intensive care nursing records on 380 inborn babies, of less than 31 weeks gestation or 1501 g birthweight, admitted to one unit between 1984-6 and 1991-4.

RESULTS

Between the two time periods mean initial illness severity score increased significantly from 2.8 to 3.9. This was the result of an increase in the maximum appropriate inspired oxygen concentration in the first 12 hours. Risk adjusted survival did not improve over time after accounting for gestation but was significantly greater after accounting for CRIB score. Illness severity score was also significantly inversely associated with gestation and 1 and 5 minute Apgar scores, using multiple regression analysis. Between the two time periods there was also a 92% increase in the admission rate of babies under 31 weeks gestation, higher median 1 and 5 minute Apgar scores (6 vs 5 and 9 vs 8, respectively), more multiple births, and more caesarean section deliveries.

CONCLUSIONS

The increase in illness severity score and admission rate may reflect changes in obstetric practice. The increase in illness severity score may also reflect changes in early neonatal care. However, after adjusting for CRIB score, risk adjusted mortality fell significantly, suggesting that neonatal care 12 hours from birth onwards had improved with time.

Factors associated with neonatal hypoglycemia in premature twins and singletons

Twin gestation is associated with higher rate of neonatal hypoglycemia than do singletons. We examined the role of specific risk factors associated with neonatal hypoglycemia of 216 premature twins and 1284 premature singletons, consecutively born in the years 1994-1996 in the Department of Pediatrics of Padua University, Italy. Significantly higher risk of hypoglycemia (Dextrostix < 40 and < 20 mg%) was found in twins vs singletons (54% vs 32%, OR 2.49, CI 1.77-3.56; 19% vs 8%, OR 2.65, CI 1.59-4.19, respectively). Gestational age of 34-37 weeks increased hypoglycemia risk for the premature twins (77% vs 51%, OR 3.20 CI 1.49-6.88). Twin deliveries statistically differed from those of singletons in several perinatal characteristics. More twins were born by cesarean section (85% vs 55%, OR 4.15, CI 2.48-6.95), and the birth weight of twins was much lower related to prematures with BW < 1.0 kg (12% vs 6%, OR 2.06, CI 1.11-3.82) and SGA (20% vs 10%, OR 2.41, CI 1.46-3.98). The risk of twin deliveries was increased at 30-33 weeks gestational age (25% vs 15%, OR 1.84; CI 1.17-2.90). Twins were found to have higher rates of hospitalization (50% vs 40%, OR 1.52, CI 1.04-2.23) and showed an increased risk of cardiorespiratory resuscitation (51% vs 31%, OR 2.36, CI 1.61-3.47), hypothermia (11% vs 4%, OR 3.02, CI 2.33-3.91), BPD (25% vs 19%, OR 2.55, CI 1.10-5.91), and PVL (4% vs 1%, OR 4.08, CI 1.23-13.5). Mortality was found more often (not significant) in premature twins. The risk for intrapartum and early neonatal morbidity was however, mostly reduced in hypoglycemic twins, while it was comparable between smaller or smaller weight discordant twins and larger twins. Similarly, SGA twins, and smaller or smaller weight-discordant twins did not show increased hypoglycemia risk. In conclusion, our findings suggest that the multiple gestation per se is the single most important relative risk factor of hypoglycemia in premature twins.

Outcome of small-for-gestational age and appropriate-for-gestational age infants born before 27 weeks of gestation

OBJECTIVE

To evaluate the consequences of being small-for-gestational age at extremely low gestational age.

METHODOLOGY

Comparison of two historical cohorts of small-for-gestational age (SGA) and appropriate-for-gestational age (AGA) infants born between 24 and 26 6/7 weeks of gestation (gestational age estimated by early ultrasound at 16 to 18 weeks). Data were collected retrospectively on 191 successive admissions to the neonatal intensive care unit between January 1, 1983, and December 31, 1992. These included: demographic and maternal information, delivery mode and condition at birth, mortality, neonatal intensive care unit morbidities (respiratory distress syndrome, intraventricular hemorrhage, patent ductus arteriosis [PDA], chronic lung disease [CLD], retinopathy of prematurity [ROP], necrotizing enterocolitis, infection), nutrition, and length of hospitalization.

RESULTS

Forty-one (21%) of the 191 infants were classified as SGA. Those with congenital anomalies (10% in the SGA and 2% in the AGA group) were excluded from further analysis. Despite a similar rate of respiratory distress syndrome (50%), the SGA infants had a greater rate of failure of indomethacin treatment for PDA closure (54% vs 32% for AGA), a higher risk for CLD defined as a need for supplementary oxygen at 36 weeks (65% vs 32% for AGA), a more prolonged need for oxygen supplementation and ventilatory support (94 days vs 68 days for AGA and 58 days vs 40 days for AGA, respectively). SGA infants were also at greater risk for developing severe ROP (stage >/=III) (65% vs 12% for AGA).

CONCLUSIONS

For infants born before 27 weeks, being small-for-gestational age confers additional risks for severe morbidity, ie, PDA ligation, CLD, and ROP.

Morbidity and mortality of discordant twins up to 34 weeks of gestational age

The combination of weight discordance and prematurity implies a high perinatal morbidity and mortality for the affected twins. Several pathomechanisms may be responsible for the weight difference in twins including a different genetic growth potential in dizygotic twins, placenta insufficiency in one twin, and chronic feto-fetal transfusion (CFFT). Little is known about neonatal morbidity and mortality of discordant twins. Therefore, a retrospective, case-controlled study on preterm discordant twins up to 34 weeks gestation was carried out. Twenty-seven (27,3%) of 99 twin pairs born in our clinic had a birth weight difference of more than 20%. The control group consisted of 27 non-discordant twins matched for gestational age. Discordant twins showed a significantly higher mortality (19%) than the control twins (2%). Severe intracranial haemorrhage (ICH) and persistent ductus arteriosus Botalli (PDA) were found more often in discordant twins than in the control group. The increased mortality and morbidity of discordant twins compared with concordant twins matched for gestational age indicates that the increased morbidity and mortality of preterm weight discordant twins is not only due to prematurity, but is also related to the discordance itself. Thirteen (48.1%) of the weight discordant twin pairs fulfilled the criteria for CFFT. Twins with CFFT differed significantly from controls with respect to the incidence of mortality and the rate of severe ICH, PDA, and the necessity of postnatal cardiopulmonary resuscitation. By contrast, no significant differences were found between discordant twins without CFFT and controls. Thus, CFFT appears to be a major contributing factor for increased mortality and morbidity of weight discordant twins. Intra-twin pair analysis revealed a higher rate of postnatal hypoglycaemia in the smaller twins only, probably caused by insufficient glycogen storage due to intra-uterine malnutrition. Mortality was the same for both the larger and the smaller twins. It may be concluded that neonatal outcome of smaller twins who have survived intra-uterine malnutrition is the same as in larger twins. Intra-twin pair analysis in twins with CFFT revealed no significant differences except for a higher rate of ICH grade 2-4 in the larger twins which might be explained by hypervolaemia of the recipient.

CONCLUSION

Morbidity and mortality of weight discordant twins are increased. CFFT appears to be a major contributing factor for the increased mortality and morbidity. Postnatal mortality was the same in acceptor and donor; however, the acceptor had a higher postnatal morbidity.