[Quantification of perinatal risk in Mexican adolescents: consequences of maternal low weight].

Objective: To determine whether a pregnant adolescent whose weight-for-age is less than 90% is on the risk of delivering a baby who is small for gestational age.

Patients And Method: Six hundred and one adolescents aged 12-16 years, at 40 weeks of gestation were included. Body weight was measured at baseline with Mexican reference tables. Low maternal weight was considered less than 90%. Rate of small for gestational age at birth was determined for each group. Comparisons were made using chi2 and relative risks were estimated.

Results: The rate of small for gestational age among adolescents with low body weight was 16.1% (30/186), it differed significantly (36/415) from the others (8.7%). Relative risk for small for gestational age babies among adolescents with low body weight was 1.9 (95% CI, 1.2 - 2.9). An exploratory analysis suggests that this effect depends on gestational age.

Conclusions: If body weight of a pregnant adolescent is to be evaluated in the absence of a previous record, tables by Arroyo can be used as reference; if body weight is less than 90%, then you have an indicator of perinatal risk.