Dossier n. 232/2013 [Abstract] Preterm births in Emilia-Romagna. 2004-2009

The nine Intensive Neonatal Care (INC) Centers of Emilia-Romagna Region have been registering since 2002 a variety of clinical data regarding all newborns with low birth weight (<1,500 grams). The variables recorded are those of the Vermont Oxfords Network (VON), furtherly enriched with data regarding the obstetric period (these data are not available in the VON).

In the 2004-2009 period 2,441 newborns were assisted within a weight range of 501-1,500 grams; these represent 1% of all newborns in Emilia-Romagna. In the same period the mortality or still birth rate for this weight-range newborns was 7% (the rate of nati-mortality was around 3‰).

An increase in the number of newborns weighting less than 1,500 grams was observed (+17.8%) in the period, which is higher than the increase in the number of all newborns (+9.4%). Only 4 out of the 9 Centers assist on average 50 or more newborns per year.

The mean age of the mothers is 31.9 years, 31.1% of them are born in a foreign country, and 36% have a low education (<5 or 8 years). A comparison with the overall population of newborns in Emilia-Romagna shows that: the frequency of newborns from nulliparous women was higher in low birth weight (53% vs. 42.9%); among multiparous women 43.9% has a history of past spontaneous abortions (vs 31% in the overall population); a subsequent intervention of assisted fertilization is shown in low-birth weight mothers vs 1.6% in the overall population of newborns.

The prevalence of maternal conditions with signs of intrauterine inflammation was: pROM (19.7%), histological chorionamnionitis (3%), abruption placentae (8%), cervical insufficiency (0.7%). The frequency of medical conditions with histological signs of placental dysfunction was: pre-eclampsia and eclampsia (14.7%), restriction of fetal growth (20.9%).

Steroidal prophylaxis to prevent respiratory distress syndrome (RDS) was given in 75.3% of cases, in 79.8% of low birth weight babies a full cycle was given. Multiparous pregnancy accounted for 28.4% of low weight birth, a proportion very similar to the one reported by VON in 2009 (29%) though quite lower than the frequency reported by INN (34.3%).

A comparison of the Emilia-Romagna low birth weight register with published data (2009) from VON (53.859 newborns) and from INN (3994 newborns) shows:

• a lower frequency in Emilia-Romagna of newborns weighting <750 grams or gestational age <27 weeks and outborns; a similar frequency of “small for gestational age babies” and multiparous women in comparison with VON;
• a lower frequency of aggressive maneuvers (endotracheal intubation, cardiac massage, adrenalin). A fourth of cases (24.3%) did not receive any resuscitation maneuver in comparison to only 10.2% in VON and to 20.2% in INN;
• a lower frequency of use of respiratory support: lower frequency of use of surfactant, higher frequency of use of nCPAP which means lower use of assisted mechanical ventilation. Keeping in mind these data (especially in comparison with VON), a lower incidence of respiratory distress syndromes and dependence to oxygen supply at 28 days and 36 weeks is to be underlined. On the contrary, the frequency of post-natal steroid therapy is higher in Emilia-Romagna in comparison to VON and INN in all weight and gestational age classes;
• a decreasing trend in the observation period of both mild (1 and 2) and severe (3-4) intraventricular hemorrhages (IVH). The frequency of grade 3 IVH is higher in comparison with VON and INN; grade 4 IVH is slightly inferior in comparison with VON and INN. If however we analyze 2010 data, severe IVH (3 and 4) are less in Emilia-Romagna than in VON and INN. The frequency of cystic leucomalacia is lower in all weight and gestational age classes in comparison to VON and quite lower than INN;
• a lower frequency of retinopathy of preterm (ROP), more prominent for mild stages (1 and 2) than for more severe stages (3 and 4);
• the frequency of perviety of ductus arteriosus (PDA) is similar to that registered in VON and slightly higher in comparison with INN (the frequency is higher in comparison with both Registers for babies born between 27 and 32 weeks of gestational age);
• the frequency of nectrotizing enterocolitis was lower in Emilia-Romagna in comparison with VON Register in all weight and gestational age classes and similar to the one observed in INN.

A fairly high variability for all outcomes considered in the 9 INC Emilia-Romagna Centers was observed.

The overall mortality rate in the 2004-2010 period was 14.2% with a fairly high variability among the 9 Centers. There was a clear decreasing trend in mortality (from 15.7% in 2004 to 10.9% in 2010). The largest reduction was observed for babies with birth weight between 501 and 750 grams and a quite clear reduction was seen for babies between 751 and 1,000 grams.

Mortality figures in the 2004-2009 period are higher in Emilia-Romagna in comparison to VON and INN especially for newborns weighting less than 1,000 grams or with gestational age <27 weeks. Emilia-Romagna register data of 2010, similar to 2009 figures, show a clear improvement in mortality rates, in particular for babies below 1,000 grams (and better than the figures presented by VON and INN).

The frequency of babies free of any medical condition was 54.4% which is lower than the one registered in INN, in particular for lower gestational age (<30 weeks) and slightly higher than the one reported in VON.