JAMA logo A prior report ascertained passive smoking to elevate chances of developing respiratory disorders. A recent study suggests that late preterm birth may be related to respiratory risk. Diseases related to the respiratory system may be more frequently observed in those born between 34 weeks and 37 weeks as compared to infants born at full term.

Having examined more than 200,000 deliveries, the authors claim that late preterm birth i.e. at 34 0/7 to 36 6/7 weeks’ gestation appears in 9.1 percent of all deliveries and three-quarters of all preterm births across the United States. Studies initiated on small populations suggest the occurrence of short-term illnesses, but this data is almost a decade old.

In the latest study, investigators analyzed the present rates of respiratory disorders among late preterm births. The data for this investigation was collected from large group of late preterm infants. In the course of the study, Judith U. Hibbard, M.D., of the University of Illinois at Chicago, and colleagues encompassed an accumulation of electronic data from 12 institutions including 19 hospitals. Information regarding 233,844 deliveries taken place in the United States between 2002 and 2008 was enclosed in the provided data.

The scientists said, “Even at 37 weeks, the odds of RDS were still 3-fold greater than that of a 39- or 40-week birth. Similar patterns were seen for transient tachypnea of the newborn, pneumonia, standard or high-frequency ventilator requirements, and respiratory failure.”

All newborns who suffered from respiratory disorders were admitted to a neonatal intensive care unit (NICU) and authors examined their charts. All late preterm births were compared with term births for resuscitation, respiratory support, and respiratory diagnoses. The authors revealed that from a total of 19,334 late preterm births, 7,055 forming 36.5 percent were admitted to a NICU. A sum of 2,032 infants was registered with respiratory compromise. While, 11,980 representing 7.2 percent of 165,993 term infants were admitted to a NICU, 1,874 appeared to suffer with respiratory illness.

The investigators allege, “We suggest that future studies should focus on indications for late preterm birth. Only by more completely understanding reasons for rising rates of late preterm birth might clinicians be able to initiate salutary interventions to decrease neonatal respiratory morbidity. Improved pregnancy dating through early ultrasound confirmation of estimated due date may help prevent neonatal morbidity associated with erroneous delivery of a neonate that is actually at an earlier gestational age. Finally, a better understanding of the effect of mode of delivery on neonates may help with future interventions to decrease morbidity.”

Respiratory distress syndrome (RDS) which is an acute lung disease of the newborn was commonly discovered by the authors. It was noted in 10.5 percent i.e. 390 newborns of 34-week deliveries. Also reduction in gestational age of up to 0.3 percent comprising 140/41,764 was observed at 38 weeks. The second most common respiratory ailment was transient tachypnea which is generally known as rapid breathing. At 34 weeks, 6.4 percent representing 236 infants displayed this disease. However, a decline was monitored of 0.3 percent showing 207/ 62,295 at 39 weeks.

Reduction in pneumonia cases was revealed from 1.5 percent to 0.1 percent at 39 weeks. At 40 weeks an overall respiratory failure was ascertained from 1.6 percent to 0.09 percent. A considerable fall in the percentage of infants with various respiratory illnesses was apparently pointed out by the scientists. With decline supposedly appeared as gestational age increased until 39-40 weeks. Furthermore, scientists claim infants born at 34 weeks display 40-fold elevation in RDS. This risk was seemingly reduced as the week of gestation progressed till 38 weeks.

The study is published in the July 28 issue of JAMA.