Bone Mineral Changes during Pregnancy and Lactation: A Longitudinal Cohort Study

Abstract

1. The influence of pregnancy, lactation and weaning on bone mineral density in healthy women was investigated during a 2 year prospective study of 59 pregnant and lactating women from the 18th week of gestation. 2. Bone mineral density was measured by dual energy X-ray absorptiometry at the non-dominant radius ultra distally and more proximally in the 18th and 37th weeks of gestation, and 0, 3, 6, 12 and 18 months after delivery. Measurements of bone mineral density of the lumbar spine, the proximal femur and the whole body were performed at all dates after delivery. 3. Reappearance of menstruation after delivery averaged 6.1 months; mean lactating period was 8.7 months. During pregnancy and lactation bone mineral density tended to decrease, but different measuring sites showed different patterns of bone mineral density changes. The reduction in the ultra distal radius during pregnancy amounted to 2%, and no further changes were observed here during lactation. After delivery, reduction in mean bone mineral density was most pronounced in the spine (5.2% in 3 months), but the fall in bone mass tended to revert after resumption of menstruation. Bone mineral density was still reduced by 3.3% after 12 months in women with menstruation resumption later than 8 months after delivery. No significant reduction was observed 18 months after delivery. No association with calcium intake, weight changes or initial bone mineral density was observed. High calcium intake did not protect against bone mineral loss in the spine and the femur. 4. Thus it can be concluded that bone loss during pregnancy and lactation took place mainly from the trabecular skeleton. Resumption of menstruation tended to result in a regain of bone mass towards baseline.

Bone mineral density and calcium metabolism of Hong Kong Chinese postpartum women—a 1-y longitudinal study

“…Other similar studies have also been limited by small sample sizes, with number of lactating subjects ranging from 9 to 26 (Hayslip et al, 1989;Cross et al, 1995;Krebs et al, 1997;Ritchie et al, 1998). This study confirmed previous studies that lactation is associated with a decrease in BMD and this effect is particularly pronounced at the lumbar spine and femoral neck (Kolthoff et al, 1998). This study also showed that the observed decrease in BMD was associated with lactation per se and was not a consequence of the mother having recently been pregnant because such bone changes were not observed in the formula feeding mothers postpartum.…”

Calcium economy in human pregnancy and lactation

“…A few studies have measured peripheral sites using DXA during pregnancy. Some showed a significant change in bone mineral at the distal radius from mid-pregnancy to shortly after delivery (41,42) , whereas others did not (39,40) .…”

“…Table 4 presents data on mean change in aBMD or BA-adjusted BMC from early lactation to after breast-feeding had stopped (8,71,82) , and Table 5 presents changes in aBMD from early lactation to after the resumption of menses (41,67,102) . In general, these studies showed either no significant net difference or an increase in bone mineral in BF women relative to 2 weeks postpartum at most skeletal sites other than the femoral neck.…”

“…These studies involved Caucasian women who had breast-fed for variable amounts of time, from about 3 months to . 18 months (8,41,42,63,80,85,89) . At 12 months postpartum, in BF women who had lactated for 3-12 months, aBMD was lower at the spine (42) , wrist (42) and trochanter (63) compared with before pregnancy.…”

Effect of HMB and 2-Ox administered during pregnancy on bone properties in primiparous and multiparous minks (Neivison vison)

“…The primary mechanism by which calcium is supplied for the support of milk production is the reduction of maternal bone mass. Bone density remains lower during continued lactation, which is independent of parathormone and vitamin D contents (8,13,15,18,19).…”