Physicians at the University of Buffalo have reported that while many babies born early may look as healthy as full-term babies, sadly some of them are not.

The study, published in JAMA Pediatrics, hopes to alert health care providers that greater vigilance is needed when caring for these early arrivals.

Term pregnancy is defined as one in which 37 to 41 weeks have elapsed since the first day of the mother’s menstrual period. Traditionally, babies born within this timeframe are thought to face the same risks.

However, this study highlights that the earlier the babies are born within this 5 week period, the higher the chances are that they will need some medical assistance.

In what is considered to be the first population-based countywide assessment of neonatal morbidity among early-term infants in the US, the researchers conclude that even though many of these babies looked healthy, they were still “physiologically immature.”

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Although ‘early term’ babies may appear healthy, medical staff should be aware that they are still physiologically immature.
Credit: Douglas Levere

Dr. Satyan Lakshminrusimha, associate professor of pediatrics at the University’s School of Medicine and Biomedical Sciences, says that the study came about after neonatologists observed that babies born at 37 or 38 weeks had more adverse health outcomes than those born at 39 to 41 weeks.

“We were seeing a significant number of infants born at 37 weeks who looked big and pretty healthy, but who, within a few hours of birth were developing low blood sugar, difficulty in breathing or needed antibiotics, necessitating admission to the neonatal intensive care unit,” he explains.

This risk increased even further if birth was by elective cesarian section – rising from 9.7% risk of admission with vaginal deliveries to 19% following a cesarian.

“Although these early-term babies appeared to be mature, providing a false assurance to clinical providers and parents, and they did well on the Apgar scores, they are nevertheless physiologically immature,” notes Dr. Lakshminrusimha, who is also the chief of neonatology at the Women and Children’s Hospital of Buffalo.

Dr. Shaon Sengupta, corresponding author of the study, hopes the study will ring alarm bells with medical staff attending these early deliveries.

She says:

Our results show the need for an increased awareness among health care providers that even though we consider babies born at 37 or 38 weeks almost term, they are still, to a large extent, physiologically immature.”

William Oh, of Brown University, and Tonse N. K. Raju, of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, say that the findings “have important implications for obstetric and neonatal care and research.”

They add that “the findings reinforce the concept that maturation is a continuum and any preset gestational age cannot be assumed to provide a clear separation between immaturity and mature.”

While the findings may sound worrying to mothers of such infants, Dr. Lakshminrusimha told Medical News Today:

“A small number of these babies do require mechanical ventilation and respiratory support during their stay in the Neonatal Intensive Care Unit. But most of these infants do well after discharge.”

He said that the main purpose of the study was to raise awareness in the community, and that mothers should not be scared to voice any concerns to the medical staff.

“With many mothers rooming in with their babies, they need to be aware of the fact that if the baby does not look well (breathing fast, grunting etc.,), the nurse or the physician should be alerted promptly at any gestational age.”

The research covered almost 30,000 live births in Erie County, NY (which includes the city of Buffalo), from January 2006 through December 2008.

These data showed that adverse outcomes experienced by the early term babies included:

37-38 weeks39-41 weeks
Low blood sugar4.9%2.5
Admission to neonatal intensive care8.8%5.3%
Needing respiratory support2%1.1%
Needing intravenous fluids7.5%4.4%
Needing intravenous antibiotics2.6%1.6%
Needing mechanical ventilation or intubation0.6%0.1%

The data revealed, for example, that twice as many of these early term babies needed mechanical ventilation, and the need for lung surfactant use was seven times higher than in term babies.

The data also showed that early term babies delivered by cesarean section were at a higher risk – by 12.2% – for admission to the neonatal intensive care, compared with full-term babies, and they were at a 7.5% higher risk for morbidity, compared with term births.

In particular, the study points out that cesarean delivery is a strong predictor of neonatal morbidity at early-term gestation.

Dr. Lakshminrusimha notes that the need for respiratory support is increased for babies delivered by cesarean section who may retain their fetal lung fluid, since they do not experience the hormonal changes of labor, which clear the fluid from the lungs.