Frequency of neonatal complications after premature delivery

© 2013 Grgiæ et al.; licensee University of Sarajevo Faculty of Health Studies. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. UNIVERSITY OF SARAJEVO FACULTY OF HEALTH STUDIES ABSTRACT


INTRODUCTION
Preterm delivery, defi ned by the WHO is the delivery before 37 weeks of gestation are completed (1).Th e incidence of preterm birth ranges from 5 to 15%.Preterm delivery is a major couse of neo-natal morbidity and mortality.It is believed that the preterm delivery is cause of neonatal death in 75% of cases and in 50% of cases leads to the creation of permanent neurological sequelae (2).According to gestational weeks, preterm delivery is divided: the extreme preterm birth (before 32 weeks of gestation), moderately preterm delivery (32-33.6weeks of gestation), and preterm delivery (34-36.6weeks of gestation) (3).Characteristics of infants born prematurely are: body weight less than 2500 grams and body length less than 48 cm, subcutaneous adipose tissue is less developed, skin turgor is normal, the epidermis is normal, color is red, the vernix caseosa present, the nails do not rise to the top of the fi ngers, lanugo is enhanced, papillary membrane is known, ear cartilage is incompletely developed, high-pole lips cover small, the testicles are maintained in the inguinal canal, the color of the amniotic fl uid is a colorless or clear (4).Extremely premature infants have immature gestational weeks less than 30 weeks.Small birth weight, with severe respiratory problems and frequent neurological complications.Th e percent of survival was 60% in the presence of sequelae in 20% of cases.Moderately premature infants are born premature between 30 and 34 gestational weeks with birth weight over 1500 grams, with lighter respiratory and metabolic problems, but can be treated successfully with modern equipment and trained staff .Th e percentage of survival is about 80%, with a small number of sequences.Marginally mature preterm are from 35-37 weeks of gestation, with a birth weight over 2500 grams.Neonates born before term can have many complications such as respiratory distress syndrome (RDS), intraventricular hemorrhage, necrotizing enterocolitis, bronchopulmonary dysplasia, sepsis, persistent ductus arteriosus, and retinopathy.Infants born before 28 weeks of gestation have a higher risk of intraventricular hemorrhage (5).Respiratory distress syndrome is the specifi c clinical entity that is primarily common in premature infants, and occurs due to the reduced amount of surfactant in the alveoli (6).RDS is the main cause of morbidity in prematurely born infants (7).Risk factors favorable to the emergence of RDS are: prematurity, male sex, diabetic mothers, perinatal asphyxia, the second born twin, familial predisposition and pregnancy terminated by cesarean section (8).According to Stefanović, incidence of RDS is 10-15% in infants born prematurely and signifi cantly rising as gestational age is lower (9).According to Crowley, the risk of developing RDS is higher than 50% if the gestational age is less than 30 weeks (10).Neonatal sepsis is an acute systemic disease of premature infants characterized by a general reaction to the infectious bacteremia.It occurs in the fi rst month of life, and caused by the penetration bacteria and their toxins in the bloodstream, where besides the general reaction.Premature infants have incomplete growth and development at all structural levels, cellular and tissue level, so it is not surprising the fact that 2/3 of the total children number born prematurely require intensive care and/or therapy within the fi rst seven days of life (11).

Subjects
Th is is retrospective study in which we analyzed and compared the frequency of occurrence of fetal complications in infants born prematurely with complications in term newborns.Th e study was conducted at the Department of Obstetrics and Gynecology and Pediatric Clinic of the University Clinical Center Tuzla.Th is research included 631 newborns, 331 infants were born prematurely (24-37 gestational weeks-experimental group), while 300 infants born in time (37-42 gestational weeks-control group).We analyzed the body weight of the newborn, Apgar scores after the fi rst and fi fth minutes, and the presence of neonatal complications in both groups.

Statistical analysis
In the analysis of results were used Student's test, χ 2 test, Mann-Whitney and Fischer's test and Spearman correlation coeffi cient.Th e diff erence between samples were considered signifi cant if p<0.05.

RESULTS
Table 1 shows the average body weight of newborns in the two groups.In premature infants average birth body weight was 2382±679 grams, while in term newborns was 3459±452 grams.Th ere was a statistically signifi cant diff erence in the average body weight infants in the experimental and control groups (t=23.62,p<0.0001).Figure 1 presents the frequency of low birth weight babies in women delivered preterm infants.Weigh less than 2499 grams had 51.1% of premature infants, while 48.9% of infants had weigh more than 2500 grams.Table 2 shows Apgar scores after the fi rst and fi fth minutes in both groups.Mann-Whitney test showed that the Apgar score after the fi rst minute, signifi cantly greater in the control group than in the experimental group (U=28368, p<0.0001), and the Apgar scores after the fi fth minutes is signifi cantly greater in the control group than in the experimental group (U=30103, p<0.0001).Table 3 shows the incidence of fetal complications in the experimental and control groups.It was found that the fetal complications were associated to membership in a particular group (χ 2 =119.3;p<0.0001).
Fetal complications were more common in premature than in term delivered infants.Th e chance of fetal complications in the experimental group was 9.52 times higher than in the control group (95% CI: 6.04 to 15.31).RDS is most prevalent in the group of premature infants born before 32 weeks of gestation in relation to the total number of preterm births (Table 4).Spearman correlation coeffi cient was 0,469, which means that the correlation is medium size, but is statistically signifi cant at the level of signifi cance p=0.01, so we can say that there is a relationship between the occurrence of RDS and weeks of gestation, and it is such that if the pregnancy would terminate at an earlier weeks of gestation, the greater the possibility for new RDS.Table 5 shows infants mortality in the two groups.Fischer's exact test has shown that the diff erence of infants mortality in the experimental and control group were statistically signifi cant (p<0.001).

DISCUSSION
In comparison with term delivery, a premature infant is immature and less able to adapt to conditions outside the mother's body.Two-thirds of children who were born before the age of 32 weeks of pregnancy with birth weight below 1500 grams can have a permanent handicap.Unfortunately, the  higher risk of permanent consequences and high mortality rates also have children in less risk groups.
Th is group includes infants born between 34 and 37 weeks of gestation, especially if you are underweight, born with infection contact and with proven change the morphology of the brain (12).According to WHO with all infants birth weight below 2500 grams, regardless of the duration of pregnancy, newborns have low birth weight.Th e term ,premature baby, is used for infants whose intrauterine growth lasted less than 37 weeks of gestation.Th erefore, preterm infants are a risk group and have high perinatal mortality, more complications in the newborn period and are more likely to infections.Th e later in life often have suboptimal psychomotor development and growth (13).In our study, we found that 3.3% of preterm infants weigh less than 999 grams, 9.1% had 1000-1499 grams, and 12.4% had 1500-1999 grams.Of the total number of 26.3% of preterm infants were born with a birth weight between 2000 and 2499 grams, while the highest number (48.9%) infants had more than 2500 grams birth weight.Overall, 51.1% of newborns were with birth weight less than 2500 grams.In a similar study Viledenčić et al. found that the percentage of infants who weighed less than 2500 grams was 59.2% (14).
On the other hand, the weight below 1500 grams we found in 12.4% of infants, which is less than in the aforementioned study where the percentage was 16%.Of the total number, we found 3.3% of preterm infants with birth weight less than 1000 grams, while a study of Viledenčić et al. found 3% of preterm infants with this birth-weight (14).Th e analysis of the average body weight between the early and timely infants, we found a signifi cant diff erence.Th e average body weight in premature infants was 2382 grams (minimum body weight was 590, and the maximum 4050 grams).Similar results were shown by Marzano et al., where the average body weight was 2241 grams (minimum body weight was 450, maximum 4300 grams) (15).In our study we found a signifi cant diff erence in the average values of Apgar score after one and fi ve minutes after birth.However, the average Apgar score in preterm infants after the fi rst minute was 7.3 and 7.7 after fi fth minutes.In infants born after 37 week gestation, average Apgar score after the fi rst minute was 8.7 and 8.9 after fi fth minutes.In the study of Marzana et al. the average Apgar score in preterm infants after the fi rst minute was 6.5, and the average term newborns Apgar scores at fi fth minute was 8.5 (15).Analyzing neonatal complications in our study we found that the most common complication of prematurity (50%) was RDS.It is known that RDS is due to lack of surfactant and inability to maintain adequate neonatal oxygenation of blood when breathing room air.Surfactant is a chemical substance that reduces the surface tension of the alveoli and helps to maintain them open at the end of expiratory fl ow, thus enhancing the functional residual capacity of the lungs, reducing the surface tension in the lungs, and protecting the lungs from total collapse and possible atelectasis during expiratory fl ow (5).We have also shown that the lower the gestational age of the pregnancy, the incidence of RDS is higher.Th e largest number of infants suff ering from respiratory distress syndrome and belongs to those born before 32 weeks of gestation (36.5%).Second in frequency of fetal complications in our study was intracranial hemorrhage.Th is complication had 28.1% of preterm and 6.8% term newborn.Th e study of Ćurković et al. intracranial hemorrhage was present at 32.24% of preterm neonates (17).Th e next most frequent complication was sepsis.Complication of prematurity had occurred in 4.8%.In neonates born between 37th and 42th gestational week there were no cases of sepsis.In the study of Ćurković et al. 9.21% of infants had sepsis (16).Analyzing neonatal mortality in our study we found that the mortality of preterm infants was 9.1%, while the neonatal mortality in term infants was 0.7%.Our results confi rm that prematurely born children make 70-85% of perinatal mortality (17).

CONCLUSIONS
Birth body weight and Apgar scores after the fi rst and fi fth minutes were lower in the preterm infants.Respiratory distress syndrome is the most common fetal complication of prematurity.Intracranial hemorrhage is the second most common complication of prematurity.Premature infant mortality is significantly higher than the mortality of infants born at term birth.

COMPETING INTERESTS
Th e authors declare no confl ict of interests.

TABLE 1 .
The average body weight infants in the experimental and control groups

TABLE 2 .
Apgar scores at the fi rst and fi fth minutes of the experimental and control groups

TABLE 4 .
Representation of RDS by gestational weeks in the experimental group

TABLE 5 .
Infants mortality in the experimental and control groups

TABLE 3 .
The incidence of fetal complications in the experimental and control groups.
FIGURE 1. Newborn infants with low birth weight in the experimental group