experts from the Spanish Society of Neonatology have studied the survival rates in Spain of newborns with a gestational age of less than 26 weeks, taking into account that a full-term newborn is between 37 and 42 weeks.
The data have been extracted from the national database that collects information on all children born weighing less than 1,500 grams. Said database is permanently updated and is used to know the results of attendance at these babies so premature, with less than 32 weeks of gestation.
“The more premature they are, the more complications they present due to their immaturity and the less chance they have of surviving,” explains Fermín García-Muñoz Rodrigo, from the Complejo Hospitalario Universitario Insular Materno-Infantil de Las Palmas de Gran Canaria and one of the authors of the This studio. “And when they do survive, they do so at great risk of neurodevelopmental and sensory sequelae.”
For this study, published in Anales de Pediatría, the experts analyzed only the smallest, that is, 3,236 babies born after 26 weeks of gestation or less. According to experts, between 22 and 25 weeks is the so-called ‘limit of viability’.
“Children of 22 weeks barely survive and, when they do, it is at the expense of experiencing many complications and long hospital stays, which means great suffering for them and their families,” adds García-Muñoz Rodrigo.
From there, chances of survival increase and the proportion of complications progressively decreases with increasing gestational age. Moreover, 26-week infants, despite being at very high risk, are considered viable and are a reference group to compare results at other gestational ages.
The results show that the specific survival rates for gestational age were 12.5%; 13.1%; 36.9%; 55.7% and 71.9% at 22, 23, 24, 25 and 26 weeks, respectively.
The survival without major intracranial hemorrhage, periventricular leukomalacia (damage to the white matter of the brain near the ventricles), bronchopulmonary dysplasia (chronic lung disorder), or retinopathy of prematurity (abnormal development of blood vessels in the retina of the eye) was 1.5%; 9.5%; 19.0% and 29.9% at 23, 24, 25 and 26 weeks, respectively.
“Survival without severe disease in children under 23 weeks of gestation is exceptional, and in newborns of 23 and 24 weeks, very low,” says the doctor. “Newborns at 25 weeks or more of gestation have a reasonable chance of survival and, in the absence of major malformations, should be offered active resuscitation and intensive care.”
Weight, sex and corticosteroids
The group of authors will soon publish another study that analyzes other possible factors that could influence the survival of these children, in addition to gestational age.
“The weight at birth -the more, the better-, the sex -girls evolve somewhat better than boys-, if the mother received corticosteroids before giving birth to mature the baby’s lungs and single versus multiple fetuses are very important factors since they all increase the chances of survival”, underlines García-Muñoz Rodrigo.
The expert concludes that medicine is not an exact science and each case must be individualized. “Other factors such as whether the fetus has malformations or not, the control of the pregnancy, the values and expectations of the parents, etc., are data that must also be taken into account.”