Veränderungen der Messergebnisse der quantitativen Ultrasonometrie (QUS) am Os Calcaneus im Verlaufe der Stillzeit

Introduction: During breastfeeding multiple mechanisms induce metabolism to adapt to the increased calcium demand. While increased intestinal resorption of calcium occurs during pregnancy, the increased calcium demand during breastfeeding is mainly provided by increased depletion of maternal bone and by a split fraction through renal retention of calcium. Aim of study: This study should investigate how the QUS parameters, which were measured via quantitative ultrasonometry at the os calcis, change after pregnancy and what influence breastfeeding has on this change. Additionally, we aimed to investigate indicators that might predict the change of the QUS parameters. Material and method: 101 Caucasian female patients in the out-patient facility setting close to Frankfurt am Main attending the regular routine pregnancy examinations and follow-up care after childbirth were included. Three measurements were performed: six weeks' post partum, six months' post partum, and at 12 months' post partum. The course of the QUS parameters, the T-score, Z-score, and Stiffness Index were determined in the groups of breastfeeding and non- breastfeeding women. Stiffness Index (SI)—a composite of Speed of Sound (SOS) and Broadband Ultrasound Attenuation (BUA)—which compensates for the effect of heel width and temperature. Baseline characteristics were surveyed by anamnesis and data was collected via ultrasonometer (Lunar Achilles plus, GE/Lunar). Results: We could not detect any significant changes in the QUS parameters over the time period after birth to 12 months' post partum. QUS parameters, T-Score, Z-Score, and SI did not change significantly in the groups breastfeeding / non- breastfeeding women. Breastfeeding was defined as a minimum of 6 months' duration. Numerically the QUS-variables of the non- breastfeeding women started on a lower level and decreased further compared to the breastfeeding group who started at higher values and even increased, though this was not significant. As a result, the predictive factors showed no influence on the QUS parameters. Although the groups breastfeeding versus non- breastfeeding showed significant differ-ences: more breastfeeding women had allergies and were significantly more often non-smokers. The same mothers declared to have been exposed to cortisone prior to preg-nancy. Breastfeeding mothers were older in the mean and had a lower BMI compared to non- breastfeeding mothers. Discussion: Our study could not demonstrate significant QUS changes in breastfeeding and non-breastfeeding women during the first 12 months after child birth. A drift could be observed which might lead to a statistical significant difference with a larger study population. The complex process in the bone during breastfeeding is not fully understood and the results of the other studies diverge. Further prospective studies with a greater number of participants are necessary to investigate the effects of pregnancy and breastfeeding on bone metabolism. Consistent results are found with postmenopausal women, here the number of pregnancies or the duration of breastfeeding have no influence on the bone.