Objective: evaluation of the impact of pregnancy and breast feeding on bone metabolism in wet nurses teenagers. Subject: 30 primigravid teenagers (EG) and 30 healthy never pregnant teenagers (CG) paired by: age(16.3±0.8 vs 16.1±0.7 years), by menarche age (12.3±1.1 vs 12.3±1.4 years) and by weight/height index (112.9±9.6 vs 106.7±12.4%). Method: daily calcium intake: blood sampling for Ca. P. alkaline phosphatase(ALP), PTH (RIA); matinal urine sampling for Ca. creatinine (c), hydroxyproline (OH-P); bone density (DPX) in lumbar spine (L2-L4), right femoral neck (RFN) and total bone calcium (TBCa). The teenagers in the study group were evaluated at 3 weeks postpartum (Stage A n=30), at 6±2 months of lactation (Stage B n=25) and at 12±4 months after weaning(Stage C n=24). The control group was evaluated in parallel. Results:(preliminary) expressed in media ± DS. Daily calcium intake (mg/day): Stage A: EG: 798±421 vs CG 640±346; stage B EG: 612±352 vs CG 592±309 stage C: EG 495±180 vs CG 456±147 mg.Table

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Conclusions: 1) In early puerperium there is high bone turnover, with reduction in bone density (L2-L4). 2) During breast leeding the high bone turnover and the low bone lumbar density persist and a reduction of total bone calcium is detected. 3) After one year of weaning, teenagers recover the bone mass lost during lactation, independent of calcium intake. (Supported by Grant Fondecyt 1930664/93)