Factors Underlying Changes in Bone Mineral During Postpartum Amenorrhea and Lactation

Abstract

To determine the physiologic and habitual factors that may modulate changes in bone mineral density (BMD) postpartum, dual-energy X-ray absorptiometry was performed at the lumbar spine, right femoral neck and dominant distal radius immediately after delivery, after resumption of menses, and 1 year thereafter in a cohort of 41 healthy postpartum Finnish women aged 31.5 (SD 4.6) years. Mean durations of lactation and postpartum amenorrhea (PPA) were 7.7 (3.7) and 5.9 (2.9) months, respectively. After PPA, significant bone losses of 2%-4% were observed at the lumbar spine and femoral neck. Duration of PPA and different lactational variables explained (adjusted R2) from 21% to 27% of the variability in changes in BMD during PPA. A recovery to postpregnancy BMD levels was observed at the lumbar spine; in contrast BMD at the femoral neck showed only a partial recovery. The duration of unsupplemented lactation was weakly (adjusted R2 = 0.13) associated with recovery at the lumbar spine, while a long duration of total lactation also showed a weak association (adjusted R2 = 0.02) with delayed recovery at the femoral neck. In conclusion, a systematic bone loss occurs during PPA, and after resumption of menstruation BMD recovers despite continued lactation. However, the time of bony recovery back to postpregnancy level seems to be modulated slightly by lactation habits. It is obvious that the control of postpartum BMD changes is a multifactorial process that may be specific to the skeletal site of interest.

Association of Physical Activity and Calcium Intake with the Maintenance of Bone Mass in Premenopausal Women

“…Radial bone seemed to recover incompletely, or its recovery took more time than that of the other bone sites. This finding agrees with the results of HolmbergMarttila et al [43], who found systematic bone recovery at the spine and femur but a diffuse response at the radius. In any case, the disproportionately large bone loss from distal radius calls for further studies.…”

“…During pregnancy the fetus takes calcium from the mother to develop its skeleton, and lactation in conjunction with postpartum amenorrhea may result in a loss of calcium and maternal bone loss. In agreement with earlier results, the postweaning recovery at the femur was not complete until well after 12 months [42][43][44]. The total duration of lactation (one long period or many periods of breastfeeding) was a predictor of radial bone loss.…”

Reproductive Factors Affecting the Bone Mineral Density in Postmenopausal Women

“…The duration of breast feeding, might affect the maternal bone mass because it suppresses the hypothalamic-pituitary axis and may result in loss of fetal calcium supply from the mother (Zarate and Canales 1987;Glerean and Plantalech 2000;Holmberg-Marttila et al 2000;Hadji et al 2002). Some studies suggest that breast feeding is not related to the BMD (Kritz-Silverstein et al 1992;Fox et al 1993).…”

Forearm bone mineral density changes during postpartum and the effects of breastfeeding, amenorrhea, body mass index and contraceptive use

“…Sample size was calculated based on a previous study of BMD measurement carried out in postpartum women, considering a standard deviation of distal radius equal to 0.044 g/cm 2 [6], an alpha of 5%, and a minimum difference between the observed and true measurements of 0.010 g/ cm 2 . The minimum sample size needed using these parameters was calculated as 74 women [7].…”