Lumbar bone mineral density changes during pregnancy and lactation.
OBJECTIVE
To elucidate the change of bone metabolism in the lumbar trabecular and its relationship with serum hormonal changes in pregnancy and lactation.


METHODS
In a cross-sectional study, we measured the bone mineral density (BMD) of 2-4 lumbar vertebrae of 571 puerperae at days 3-5 postpartum and 341 healthy, non-pregnant women (control subjects) of approximately the same age by dual energy X-ray absorptiometry. In a longitudinal study, we also measured the BMD of 111 puerperae at 3 and 6 months after delivery.


RESULTS
The mean BMD at days 3-5 postpartum was significantly lower than that of the control (1.013+/-0.005 vs. 1.032+/-0.006 g/cm2, P = 0.019). The lactating group showed BMD decrement to 95.1+/-0.5% (n = 69) and 94.1+/-0.7% (n = 61) at 3 and 6 months postpartum, respectively, compared with days 3-5 postpartum, and the amenorrhea group showed the same tendency. The non-lactating group and resumption of menses group did not show a BMD decrement postpartum. In the lactating group, serum estradiol was significantly lower than in the non-lactating group at 3 months postpartum, serum prolactin and bone alkaline phosphatase levels were higher than in the non-lactating group at 3 and 6 months postpartum.


CONCLUSIONS
Pregnancy may cause a decrease of lumbar BMD, and the lactation and amenorrhea also cause a decrease of BMD. In addition to lactation status, the ovarian dysfunction is one of the factors in bone loss during lactation.
Honda
A
A
Department of Obstetrics and Gynecology, Niigata University School of Medicine, Niigata City, Japan. akirahon@med.niigata-u.ac.jp
Kurabayashi
T
T
Yahata
T
T
Tomita
M
M
Takakuwa
K
K
Tanaka
K
K
D015502:Absorptiometry, Photon; D000328:Adult; D000469:Alkaline Phosphatase / Q000097:blood; D015519:Bone Density / Q000502:physiology*; D003430:Cross-Sectional Studies; D004958:Estradiol / Q000097:blood; D005260:Female; D006801:Humans; D007774:Lactation / Q000378:metabolism*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000378:metabolism; D011247:Pregnancy / Q000378:metabolism*; D011388:Prolactin / Q000097:blood