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

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.

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.

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.

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.