Incidencia del prematuro tardío. Morbilidad asociada en el periodo neonatal

Résumé

”Incidence of late preterm infants. Associated morbidity in the neonatal period” ABSTRACT Introduction Late preterm infants, i.e. babies who are born between 34th weeks 0 days and 36th weeks 6/7 days from the last menstrual period, have higher morbidity and mortality rates than term infants (gestational age ≥37 weeks) in the neonatal period. During the birth hospitalization they are more likely to have respiratory morbidity, neonatal depression, hypothermia, hypoglycemia, feeding difficulties, risked/suspected infection and jaundice. As a result, late preterm infants have a longer average birth hospital stay and higher rates of admission in neonatal intensive care units. During the rest of the neonatal period they also have higher rates of readmission. As the majority of the published studies are retrospective, it seems appropriate to conduct a prospective study to try to minimize biases and errors in data collection, thus making the results more reliable. Hypothesis Late preterm infants have higher morbidity than term infants who are born between 39th and 40th weeks of gestational age (“Gold Standard” of term infants) and this morbidity is greater the lower gestational age they have. Objectives We seek to analyze and quantify neonatal morbidity in late preterm infants born in our hospital, and to compare it with that of term infants born between 39 and 40 gestational weeks. We seek to also compare neonatal morbidity within late preterm subgroups, clustering them by complete gestational week (34, 35 and 36 weeks). As secondary objectives we want to evaluate the late preterm incidence in our centre, to evaluate the effects of several variables on neonatal morbimortality of late preterms (type of delivery, gender, type of feeding, etc.), to try to analyze possible causes of late preterm deliveries and to compare the neonatal morbidity data on late preterms born in our centre with the figures available in the literature. Methods We carried out a 2/1 prospective cohort study with temporal pairing. For each late preterm newborn two term newborns were chosen. The selection criterion for those newborns was temporal: the ones born just before and just after the late preterm included in our study. We gathered data on family antecedents, gestation data and delivery data from the mother stories, and we collected evolution data on the birth hospitalization period from the newborn story accumulated while he/she stayed in the hospital. To evaluate late neonatal morbidity (from discharge until 28 days of life) the parents were surveyed (by telephone or email) after the first month of life. We collected as variables for analysis: mother antecedents, gestation and delivery data, complications and special needs during the birth hospitalization period and, while in the late neonatal period, hospital and health centre follow up, the need for emergency care and hospital readmissions. Results Late preterms amount for 4.7% of all alive newborns in our hospital during the study interval, and 72% of all preterms. 18% were 34 gestational weeks, 31% were 35 gestational weeks and 51% 36 gestational weeks. Among the gestation variables analyzed, assisted reproductive technologies, gestation complications, use of tocolytic agents and use of antenatal steroids for fetal lung maturation were more frequent in the late preterm group, and within it, most of those variables were more frequent in the subgroups of lower gestational age: 35 gestational weeks and specially 34 gestational weeks. Concerning delivery data, elective induction of labor, caesarean delivery, need for advanced resuscitation and later readmission in neonatal care unit were more frequent in the late preterm group. During the birth hospitalization period, late preterm newborns had greater incidence of all analyzed complications, and after performing multivariable logistic regression, those differences stayed in all cases except for risked/suspected infection. The share of breastfeeding at discharge time was lower than the one of term newborns. When analyzing late preterm subgroups, the total amount of problems appearing in the birth hospitalization period, age at discharge and the need for hospital follow-up grew as gestational age decreased. Finally, on evolution during the first month, we got survey answers from 93% of late preterms and 86% of control group newborns (p=0.005). Late preterms had greater readmission rate than the control group, with jaundice being the main cause. There were no significant differences on visits to hospital emergency services. Conclusions In our studied cohorts, the late preterm group suffers from greater morbidity during the birth hospitalization than the term group, and that morbidity increases as gestational age decreases. Late preterm infants require hospital follow-up after discharge at a greater rate and suffer from more readmissions during their first month of life, with jaundice being the main readmission cause.