Early puberty: rapid progression and reduced final height in girls with low birth weight.

OBJECTIVE To assess whether, in girls with early onset of puberty, low birth weight is a risk factor for rapid progression to menarche and for short adult stature. DESIGN Longitudinal clinical assessment of 54 Catalan (Northern Spanish) girls followed from early onset of puberty (onset of breast development between 8.0 and 9.0 years of age) to final height. The timing of menarche and the final height were analyzed a posteriori according to birth weight, the cutoff level between normal and low birth weight subgroups being -1.5 standard deviation (SD; approximately 2.7 kg at term birth). RESULTS Normal and low birth weight girls had similar target heights and characteristics at diagnosis of early puberty. However, menarche occurred on average 1.6 years earlier in low versus normal birth weight girls (11.3 +/-.3 years vs 12.9 +/-.2 years), and final height was >5 cm shorter in low birth weight girls (parental adjusted height SD: -.6 +/-.2 cm vs.3 +/-.2 cm). CONCLUSION The timing of menarche and the level of final height in Catalan girls with early onset of puberty was found to depend on prenatal growth. Girls with normal birth weight tend to progress slowly through puberty with a normal timing of menarche and normal final height. In contrast, girls with low birth weight tend to progress relatively rapidly to an early menarche and to a reduced final height. If these findings are confirmed in other ethnic and/or larger groups, then a subgroup has been identified that will most likely benefit from any therapeutic intervention aiming at a delay of pubertal development and/or an increase of final height.