Bone Mineral Density in Gravida: Effect of Pregnancies and Breast-Feeding in Women of Differing Ages and Parity

Changes of bone during pregnancy and during lactation evaluated by bone mineral density (BMD) may have implications for risk of osteoporosis and fractures. We studied BMD in women of differing ages, parity, and lactation histories immediately postpartum for BMD, -scores, and -scores. Institutional Review Board approval was received. All women while still in hospital postpartum were asked to participate. BMD was performed by dual-energy X-ray absorptiometry (DXA) machine at femoral neck (FN) and lumbar spine (LS) by a single technician. Of 132 participants, 73 (55.3%) were ≤30 years; 27 (20.5%) were primiparous; 36 (27.3%) were grand multiparous; 35 (26.5%) never breast fed. Mean FN -scores and -scores were higher than respective mean LS scores, but all means were within the normal limits. Mean LS -scores and -scores were highest in the grand multiparas. There were only 2 (1.5%) outliers with low -scores. We conclude that, in a large cohort of Israeli women with BMD parameters assessed by DXA within two days postpartum, mean -scores and -scores at both the LS and FN were within normal limits regardless of age (20–46 years), parity (1–13 viable births), and history of either no or prolonged months of lactation (up to 11.25 years). 1. Introduction Concerns exist regarding changes in the structure and metabolism of bone during pregnancy and the early postpartum period including during lactation that may have implications for short-term and long-term risk of osteoporosis and fractures. Since calcium mobilization [1] and bone resorption increase at the end of pregnancy and increase further with lactation [2], there has been considerable controversy over the past decades as to whether high parity and/or prolonged lactation periods are detrimental to bone mineral density (BMD). Although there is loss of BMD during pregnancy [3] and during lactation [4], it may be considered to be transient. Yet it has also been suggested that factors such as age at and duration of menopause [5–7] may be the more definitive risk factors for osteoporosis and fractures. Recently, it has been shown that pregnancies [8] and long or repeated periods of breast-feeding do not seem to be associated with emergence of osteoporosis in later life [7, 9]. In fact, women with multiple pregnancies have been shown to have the same or higher BMD [10] and lower fracture risk decades after last parturition [6, 7] when compared with nulliparous women. International studies in various populations of women with high parity [10, 11] and motivated to repeated periods of lactation generally confirm good