New references for neonatal weight by gestational age and sex, Holguín, Cuba.

Introduction: Birth weight is considered to be the best predictor of an infant's health status in the neonatal phase. In the Americas, several studies have set the foundation for determining references birth weights. In Cuba there is a report on anthropometric patterns in neonates in 1990 from a maternity ward in Havana, but there are no updated neonatal weight distribution curves by gestational age and sex, as suggested by WHO.

Objective: Create birth weight percentile distribution tables and curves for neonates by gestational age and sex in Holguín Municipality, capital of the eastern Cuban province of the same name.

Methods: A retrospective longitudinal study was designed in a universe of 16,018 neonates born alive, delivered within a gestational range of 30 to 42 weeks in the maternity unit of the V.I. Lenin University General Hospital in Holguín Municipality between January 2008 and December 2012. Included were neonates born in the study hospital living in Holguín Municipality; neonates from multiple births were excluded. Variables included gestational age, sex, and birth weight. Gestational age- and sex-specific weight percentile distribution tables and curves were constructed based on observed values. A third-degree polynomial was applied via weighted least squares regression to smooth distribution curves. Analysis of variance was conducted to compare four years (2008, 2009, 2010 and 2011) and the coefficient of variation was calculated for each week of gestation.

Results: The average weight of neonates of both sexes rose from week 30 to week 42. The coefficient of variation between weeks 34 and 42 was 11.6%-19% in girls and 12.1%-21.3% in boys. The 10th percentile value at 36 weeks of gestation was 2140 g for girls and 2200 g for boys. For girls, cutoff points for the 10th percentile (small for gestational age infant) were higher at 34-42 weeks and for boys at 36-42 weeks. Applying our cutoff points to this population identified 47% more low birth weight infants than did previously applied standards.

Conclusions: Marked differences were found when comparing our tables with tables from other countries. The higher references values for the 10th percentile (compared to previous ones in Cuba) in mean more neonates fall in the low birth weight category, providing greater opportunities to reduce morbidity and mortality in this high-risk group.