Lisa Spindler Photography Inc. / Getty Images Corticoid drugs have been used for over 10 years to speed up the maturing of premature babies born after six to seven months of pregnancy (24 to 34 weeks) in order to reduce their respiratory problems. For the so-called late preterm infants, born between 34 and 36 weeks, physicians have also used corticoids, but there were doubts as to whether this strategy actually worked. Now, a study with 320 pregnant women being cared for at the Prof. Fernando Figueira Integral Medicine Institute (Imip), in the city of Recife, showed that giving them this drug makes no difference: there were no relevant gains in the state of the health of the babies of the 157 women who took a placebo as compared to those of the 163 who took a corticoid, other than the fact that the babies in the latter group had slightly less jaundice than those in the first group.
This study, the first of its kind conducted in Brazil, may help physicians rethink their strategies for dealing with preterm pregnancies ending between 34 and 36 weeks – the infants born after 37 weeks, called term infants, are considered normal. “Previously, we used to name the late preterm infants ‘near-term’, as we thought they wouldn’t have too many problems,” says Melania Amorim, a professor from the Federal University of Campina Grande (UFCG), an Imip physician and the coordinator of this study. “Later we found that they have fewer health problems than a preterm baby, but more than a normal baby, and they require special care.”
The premature infants and to a lesser extent the late preterm ones usually suffer mainly from respiratory problems, as their lungs are immature. They also tend to have metabolic disturbances, digestive difficulties and jaundice. Prematureness, which tends to go hand-in-hand with these problems, accounts for some 40% of child mortality. According to the US National Institute of Child Health, the mortality of preterm infants born weighing 501 to 750 grams (g) is 60%; from 750 g to 1 kilogram (kg), 23%; from 1kg to 1.2 kg, 10%; and above 1.250 kg, 7%. A normal baby is born weighing 2.8 to 3.2 kg.
“Since the 1990s, corticoids have substantially helped to lower the consequences of premature births,” says Melania, who has been mindful of the efficacy of this kind of medication since her doctorate, completed in 1998. “We used to believe that it would also be effective for late preterm babies, but unfortunately it wasn’t. It’s indifferent whether or not they take the drug. The corticoid won’t improve their respiratory discomfort. We have to come up with another strategy to deal with this problem.” Though ineffective, corticoids, thanks to the low dosages used, should not damage the immune system, according to the researcher. Among adults, corticoids may often weaken the body’s defenses against microorganisms and tumors.
Of the 320 pregnant women who took part in the study in the Recife hospital, 163 were given corticoids and 157, placebo, between April 2008 and June 2010. The liquids that were injected as a single dose had the same color, volume and packaging; they were identified by a code and only the pharmacist who had prepared them knew which was which. In each group, 143 and 130 late preterm babies were born, the state of whose health was fairly similar, according to the article that describes the details of the study, published in April in the British Medical Journal (BMJ). The rate of respiratory discomfort syndrome was low (two babies in the group of mothers that took a corticoid and one in the control group), but of excessively rapid respiration, i.e., tachypnoea, was high (24 and 29 in each group).
The need for artificial respiration was about 20% in both groups. There was no substantial difference in neonatal morbidity (88 babies from the corticoid mothers and 93 from the placebo mothers) or in how long the babies had to stay in hospital for (5.1 days in the first group and 5.2 in the second). Melania highlights that these results, though positively commented on in one of the BMJ editorials, must be reiterated by other teams in broader studies. A large study on 2,800 women is under way in the United States and its results are expected in 2013.
“The results are clinically and scientifically important,” commented the Brazilian physician Jaques Belik, a pediatrics professor from the University of Toronto, Canada. “In my opinion, this study definitely confirms that corticosteroids are not indicated in pregnancies in which the waters break after 34 weeks.” Ruth Guinsburg, a pediatrics professor from the Federal University of São Paulo (Unifesp), warns that late preterm infants are a source of concern worldwide. “In Brazil,” she says, “with the alarming rates of caesarean sections devoid of a clear indication before 39 weeks, the concern with late preterm births is even greater.”
The high number of elective caesarean sections not including natural childbirth, after 37 to 38 weeks of pregnancy and often planned interruption between 34 and 36 weeks due to mother or baby morbidity, according to her, “result in an absolute number of worrying newborns.” Infants born under these circumstances generally undergo intensive care, require phototherapy, have difficulty suckling, and remain hospitalized for 5 to 10 days, “which generates an emotional cost for the families, financial costs for the country, and the possibility of consequences for the children.”
She reminds us that a substantial part of the brain’s development occurs between the 34th and the 40th weeks of pregnancy. This is one of the reasons why late preterm pregnancies can damage a child’s learning capabilities at school age. “It’s logical that some of these pregnancies show undeniable indication of an early birth,” she says. “However, there is another part in which extending pregnancy or birth after the start of labor would be beneficial in all senses.” What the Recife physicians saw was enough to cause them to rethink the care strategies for pregnant mothers of probable premature births. “Now, whenever possible, we try to maintain pregnancy and postpone delivery for the baby to be born after 37 weeks,” says Melania. “We’re already changing the routine of the obstetrics service to provide better care for the late preterm babies.”
PORTO, A.M.F. et al. Effectiveness of antenatal corticosteroids in reducing respiratory disorders in late preterm infants: randomized clinical trial. BMJ. 2011. On-line