[Intrauterine growth in a selected group of Peruvian twins]

Newborn twins have high risk of morbidity and mortality. They are classified with intrauterine growth curves of unique fetuses; they do not exist Peruvian curves for this group.

To know the intrauterine growth of a selected group of Peruvian twins and compare it with patterns of unique newborns.

In a descriptive, transversal and prospective study made during 13 years (1992-2004) at the Hospital Hipólito Unanue of Tacna-Peru we selected 282 twins (54%) without factors that alter the intrauterine growth. We obtained averages, standard deviation and percentiles 10, 50 and 90 of weight, height, and cephalic perimeter for gestational age of 32 to 41 weeks, which were corrected with a second-order polynomial. We compared the values of the percentiles and the averages with the unique newborns curves. The value of p < 0.05 was considered significant.

From 36,909 newborns alive, 518 were twins, and of those we selected 282. The most representative group was formed by those who were in the week 38, in which percentiles 10 and 90 of weight were 2,275 and 3,180 g, of size 45.8 and 48.4 cm, and of cephalic perimeter 323 and 354 mm, respectively. Comparing the twins with the unique newborns at week 38, the difference of weight in percentile 50 was 452 g. Regarding the somatometric parameters, weight was the most affected, 44.3% of the twins were under percentile 10 of the curve of weight for unique newborns; followed by height with 22.3% and cephalic perimeter with 5%. When comparing the intrauterine growth for weight of twins with unique newborns the performance was similar until week 34, from which growth had a significant deterioration. When classifying the newborn twins we found a frequency of 12.3%, which increases to 37% with the curves of unique newborns.

The twin intrauterine growth curves differ significantly from the unique newborns growth. It is recommended to use specific charts for twins in order to evaluate their intrauterine growth appropriately.