The effect of menarche age, parity and lactation on bone mineral density in premenopausal ambulatory multiple sclerosis patients

Although pregnancy and breast-feeding do not have any deleterious effect on disease activity in female multiple sclerosis (MS) patients, their role on bone mineral density (BMD) and osteoporosis risk is unknown. We investigated the role of age at menarche, parity and lactation on BMD expressed as percentage of the mean BMD (%BMD) in 46 pre-menopausal ambulatory female MS patients using dual-energy X-ray absorptiometry (DXA) scans in lumbar spine (LS) and hip. MS female patients with age at menarche ≥13 years old had reduced %BMD compared to those with menarche age <13 years (95.2±10.7 vs 102.1±13.3, p=0.05 in LS; 90.5±12.6 vs 99.8±12.6, p=0.02 in hip). Parity did not result in any statistically significant changes in either LS or hip. Patients that breastfed their offspring compared to those that did not had significantly lower BMD in both LS (93.9±9.3 vs 110.7±15.6, p=0.004) and hip (91.6±10.7 vs 105.6±15.3, p=0.02). MS female patients with menarche at age≥13 years and those who breastfed their offspring may have reduced BMD. Larger studies are needed to verify these findings and establish a definite role of menarche age and breast feeding with BMD.