Bone mineral density in gravida: effect of pregnancies and breast-feeding in women of differing ages and parity

Lumbar spine bone mineral density in women breastfeeding for a period of 4 to 6 months: systematic review and meta-analysis

BACKGROUND

During the breastfeeding period, important transient changes in calcium homeostasis are verified in the maternal skeleton, to meet the demand for calcium for breastmilk production. The literature is inconclusive regarding the causes and percentages of involvement of bone densitometry resulting from exclusive breastfeeding (4 to 6 months).

METHODS

This article aims to systematically review the literature, to determine the occurrence, intensity, and factors involved in alterations in maternal bone mineral density (BMD), during a period of 4 to 6 months of exclusive breastfeeding. The search descriptors "woman", "breastfeeding", "human milk", and "bone mineral density" were used in the electronic databases of the Virtual Health Library, Scielo (Scientific Electronic Library Online), CAPES Periodicals Portal, LILACS, Embase, PubMed/Medline, Cochrane, Scopus, and Web of Science in June 2023. Inclusion criteria for breastfeedingmothers were; aged to 40 years, primigravida, exclusively breastfeeding, with BMD assessments using dual-energy X-ray absorptiometry (DXA), with values expressed at baseline and from 4 to 6 months postpartum. The Jadad scale, Newcastle-Ottawa Scale, and Oxford Centre for Evidence-based Medicine - levels of evidence were adopted to assess the quality of the studies. For the meta-analytical study, statistical calculations were performed.

RESULTS

Initially, 381 articles were found using the search strategy and 26 were read in full. After risk of bias analysis, 16 articles remained in the systematic review and four were included in the meta-analysis. The studies showed a reduction in bone mass in the lumbar spine in the first months postpartum (4 - 6 months), when compared with a longer period of breastfeeding (12-18 months). The breastfeeding group presented a greater impact in the meta-analysis than the control group (non-breastfeeding, pregnant, or immediate postpartum), with a reduction in BMD in the lumbar spine of -0.18 g/cm2 (-0.36, -0.01 g/cm2); 95% Confidence Interval, on a scale from 0 to 10.

CONCLUSIONS

Our results demonstrated a transitory reduction in bone densitometry of the lumbar spine during exclusive breastfeeding for 4 to 6 months, which was gradually restored later in the postpartum period. More prospective studies are needed to better understand the topic.

TRIAL REGISTRATION

PROSPERO platform (nº CRD42021279199), November 12th, 2021.

Bilateral atraumatic femoral neck fractures resulting from transient osteoporosis of the hip

A woman in her mid-30s presented to the orthopaedic team, unable to mobilise, shortly after her caesarean section. On questioning, she reported 10 weeks of atraumatic right hip pain. A radiograph revealed a displaced right subcapital neck of femur fracture. An MRI confirmed this, as well as identifying a minimally displaced left subcapital neck of femur fracture. She underwent a right total hip replacement and internal fixation of the left hip. A dual energy X-ray absorptiometry (DEXA) scan showed severe osteoporosis, and a diagnosis of transient osteoporosis of the hip was made. She was seen by the bone metabolism team and given calcium and vitamin D medication. Although atraumatic hip fractures are rare in young patients, disproportionate or persisting hip pain in pregnant patients should raise the index of suspicion and prompt further investigation in the form of an MRI. This will allow timely management of hip fractures and improve patient outcomes.

Pregnancy- and lactation-associated osteoporosis with vertebral fractures: a systematic review

BACKGROUND

To review, analyze and characterize the pregnancy and lactation-related osteoporosis (PLO) with vertebral fractures based on the extraction data in the previous studies.

METHODS

A comprehensive literature search of electronic databases including the PubMed, Embase and Web of Science was conducted from January 1st,1990 to December 1st, 2020. The enrolled data were pooled to analyze the baseline characteristics, clinical features, risk factors and treatment options.

RESULTS

A total of 65 articles with 338 cases were enrolled for data extraction. The enrolled cases aged from 19 to 47 years, with a mean value of 35.7 years old. The average body mass index (BMI) was 22.2 kg/m2 ranged from 16.0 to 39.0 kg/m2. Of the 173 cases, 149 cases with vertebral fractures occurred in the first pregnancy, 19 cases in the second pregnancy, four cases in the third pregnancy and one case in the fourth pregnancy. Up to 91.5% of the back pain occurred within the last 3 months of pregnancy and the first 3 months after delivery. The most involved vertebral levels were L2, L1 and T12 accounting for 32.6% of all the fractures. The average fracture numbers were 4.4 levels per patient. The lumbar Z-scores were mostly recorded with a mean value of - 3.2 ranged from - 7.8 to 0.

CONCLUSIONS

PLO with vertebral fractures is a rare clinical entity, which is more likely to occur in older and thinner pregnant women. Back pain is the clinical complaint and mostly occurs in the late pregnancy and early lactation periods. Most vertebral fractures appear in the first pregnancy but it can occur in any time of pregnancy. Thoracolumbar region is the mostly involved region. As compared with postmenopausal osteoporotic fractures, PLO usually has multiple levels fractures. Bisphosphonates are the most widely used treatment so far, however, many factors need to be taken into account to decide which drug to choose in PLO and further studies are necessary for clear recommendation in the future.

Quantitative ultrasound assessment of the effect of parity on bone mineral density in females

Background

The effect of pregnancy and breastfeeding on a female’s bone mineral density (BMD) is controversial. This prospective study aims to investigate the effect of parity on BMD among pre-menopausal multiparous females using quantitative ultrasound as a screening method and females with no pregnancies (nulliparous) as a control group.

Methods

A portable ultrasound-based bone densitometer (DMS PEGASUS SMART, Mauguio, France) was used to indirectly assess the BMD in 51 multiparous (29–45 years) and 51 nulliparous Arabic females (18–35 years) by quantifying the broadband ultrasound attenuation (BUA) from their right calcaneus bone. BUA > 70 db/mhz = normal, BUA 65–69.9 db/mhz = below average, BUA 55–64.9 db/mhz = osteopenia and BUA < 55 db/mhz = osteoporosis.

Results

There was a significant difference in mean BUA between multiparous and nulliparous females (74.1 db/mhz vs. 69.3 db/mhz, p = 0.006). The prevalence of normal BMD was significantly higher in the nulliparous group than in the multiparous group (70.6% vs. 47.1%, p = 0.02). Osteoporosis was found in the multiparous group only (3/51). Among the multiparous females who breastfed (43/51), a total of 51.2% (22/43) had normal BMD, 25.6% (11/43) had BMD below average, 18.6% (8/43) had osteopenia and 4.7% (2/43) had osteoporosis. No significant differences in mean BUA (p = 0.2) were found between the group of females who breastfed for one year (13/43; BUA: 70.5 ± 9.4), the group of females who breastfed for 6–11 months (8/43; BUA: 70.6 ± 10.0) and those who breastfed for less than six months (22/43; BUA: 71.6 ± 9.4). A binary logistic regression model built for predicting BMD normality showed significance for the variable parity (p = 0.03), while the effect of the possible confounding variables BMI and age on BMD normality was found to be non- significant (p = 0.1 and p = 0.6, respectively).

Conclusion

Parity affects the BMD, as assessed by a portable ultrasound-based bone densitometer, of young and middle-aged females as compared to the BMD of nulliparous females.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12905-021-01516-w.

Does parity and duration of lactation have any effect on the bone mineral density of the femur and lumbar spine in Indian women? A cross-sectional study from the Northeast region of India

Background:

The effects of multiple pregnancies and period of lactation on bone density have not been studied till date and there is very less data available, especially from developing countries like India. Lumbar spine and femoral neck were used to measure BMD and results were recorded.

Objective:

To find out the effect of parity and period of lactation on occurrence of osteoporosis in spine and femoral neck in women of the Northeast region of India.

Materials and Methods:

The cross-sectional study included 294 perimenopausal and postmenopausal women aged 30–65 year old. Age, body mass index (BMI), parity, total lactation period, menopausal status, duration of menopause socioeconomic status, and nutritional history were noted. The dual-energy X-ray absorptiometry system was used to measure the BMD of lumbar and femoral neck BMD. Multiple regression analysis was done for finding out the association of parity and lactation with BMD.

Results:

The parity was inversely related with BMD of lumbar spine (β = −0.138, P = 0.00423) and BMD of femoral neck (β = −0.142, P = 0.00487). This relation remained significant after adjusting for age, BMI, and duration of menopause. Period of lactation was also inversely correlated with BMD for lumbar spine (β = −0.0812, P = 0.0012) and BMD of femoral neck (β = −0.033, P = 0.0031).

Conclusion:

The number of parity and prolonged period of lactation have a negative effect on BMD in both regions especially in the lower socioeconomic strata with poor nutritional intake. Our data supports that parity and duration of lactation can be associated with future osteoporosis.

Bone Mineral Density Changes Associated With Pregnancy, Lactation, and Medical Treatments in Premenopausal Women and Effects Later in Life

Bone mineral density (BMD) changes during the life span, increasing rapidly during adolescence, plateauing in the third decade of life, and subsequently entering a phase of age-related decline. In women, menopause leads to accelerated bone loss and an increase in fracture risk. Between peak bone mass attainment and menopause, BMD is generally stable and the risk of fracture is typically low. This time period is marked by life events such as pregnancy and lactation, which transiently decrease BMD, yet their long-term effects on fracture risk are less certain. BMD may also be altered by exposure to medications that affect bone metabolism (e.g., contraceptives, glucocorticoids, antidiabetic medications, antiepileptic drugs). Although oral contraceptives are often believed to be neutral with regard to bone health, depot medroxyprogesterone acetate (DMPA) and gonadotropin-releasing hormone (GnRH) agonists have been associated with decreases in BMD. Development of newer medical therapies, principally GnRH antagonists (e.g., ASP1707, elagolix, linzagolix, relugolix), for treatment of endometriosis-associated pelvic pain and heavy menstrual bleeding due to uterine fibroids has renewed interest in the short- and long-term impacts of changes in BMD experienced by premenopausal women. It is important to understand how these drugs influence BMD and put the findings into context with regard to measurement variability and naturally occurring factors that influence bone health. This review summarizes what is known about the effects on bone health pregnancy, lactation, and use of DMPA, GnRH agonists, and GnRH antagonists in premenopausal women and potential consequences later in life. ClinicalTrials.gov identifier: NCT03213457.

MicroRNA-672-5p Identified during Weaning Reverses Osteopenia and Sarcopenia in Ovariectomized Mice

Post-menopausal condition augments the biological aging process, characterized by multiple metabolic disorders in which bone loss is the most prevalent outcome and usually coupled with sarcopenia. Coexistence of such associated pathogenesis have much worse health outcomes, compared to individuals with osteoporosis only. Pre- and post-natal bone development demands calcium from mother to fetus during pregnancy and lactation leading to a significant maternal skeletal loss. It follows an anabolic phase around weaning during which there is a notable recovery of the maternal skeleton. Here, we have studied the therapeutic effect of microRNA-672-5p identified during weaning when it is predominantly expressed, in ovariectomized mice for both osteopenia and sarcopenia. miR-672-5p induced osteoblast differentiation and mineralization. These actions were mediated through inhibition of Smurf1 with enhanced Runx2 transcriptional activation. In vivo, miR-672-5p significantly increased osteoblastogenesis and mineralization, thus reversing bone loss caused by ovariectomy. It also improved bone-mineral density, load-bearing capacity, and bone quality. Sarcopenia was also alleviated by miR-672-5p, as we observed increased cross-sectional area and Feret's diameter of muscle fibers. We hypothesize that elevated miR-672-5p expression has therapeutic efficacy in estrogen-deficiency-induced osteopenia along with sarcopenia.

Comparison of Measurements of Bone Mineral Density in Young and Middle-Aged Adult Women in Relation to Dietary, Anthropometric and Reproductive Variables

The objective of this study was to compare current measurements of bone mineral density (BMD) of the lumbar spine (LS), femoral neck (FN), and total femur (TF) regions with initial values recorded 12 years ago in women from Northwest Mexico, and evaluate their correlation with dietary, anthropometric, and reproductive variables. BMD was assessed by Dual-energy X-ray absorptiometry. Participants were grouped as follows: Nulliparous (G1); women who were mothers 12 years ago (G2); and women who were nulliparous 12 years ago, but are now mothers (G3). In all three groups, current LS BMD was higher than initial (p ≤ 0.05) and current TF BMD in G2 was higher than initial values (p ≤ 0.05). When comparing current FN and TF BMD among the three groups, G2 had higher values than G3 (p ≤ 0.05). G2 also showed higher LS BMD than G1 and G3 (p = 0.006). Age at menarche was inversely-correlated with FN and TF BMD in G1 (p < 0.01), while the body mass index (BMI) correlated positively with all three bone regions in G2 (p < 0.05). This study shows that in women without and with children, age at menarche, BMI, and age were factors associated to BMD in healthy subjects in reproductive age.

Pregnancy-related osteoporosis and spinal fractures

Pregnancy-related osteoporosis is a very rare condition characterized by the occurrence of fracture during pregnancy or the puerperium. Despite its relative rarity, it can be a dangerous condition that causes severe back pain, height loss and disability. Normal physiologic changes during pregnancy, genetic or racial difference, obstetrical history and obstetrical disease, such as preterm labor or pregnancy-induced hypertension, are presumed risk factors of pregnancy-related osteooporosis. However, exact etiology and pathogenesis are uncertain. The management and natural history are still poorly defined. Traditional medications for osteoporosis are calcium/vitamin D and bisphosphonate. Concerns with bisphosphonate include accumulation in bone and fetal exposure in subsequent pregnancies. The newly developed medication, teriparatide, has shown good results. We report six cases of pregnancy-related osteoporosis and spinal fracture with literature review.

Maternal Mineral and Bone Metabolism During Pregnancy, Lactation, and Post-Weaning Recovery

During pregnancy and lactation, female physiology adapts to meet the added nutritional demands of fetuses and neonates. An average full-term fetus contains ∼30 g calcium, 20 g phosphorus, and 0.8 g magnesium. About 80% of mineral is accreted during the third trimester; calcium transfers at 300-350 mg/day during the final 6 wk. The neonate requires 200 mg calcium daily from milk during the first 6 mo, and 120 mg calcium from milk during the second 6 mo (additional calcium comes from solid foods). Calcium transfers can be more than double and triple these values, respectively, in women who nurse twins and triplets. About 25% of dietary calcium is normally absorbed in healthy adults. Average maternal calcium intakes in American and Canadian women are insufficient to meet the fetal and neonatal calcium requirements if normal efficiency of intestinal calcium absorption is relied upon. However, several adaptations are invoked to meet the fetal and neonatal demands for mineral without requiring increased intakes by the mother. During pregnancy the efficiency of intestinal calcium absorption doubles, whereas during lactation the maternal skeleton is resorbed to provide calcium for milk. This review addresses our current knowledge regarding maternal adaptations in mineral and skeletal homeostasis that occur during pregnancy, lactation, and post-weaning recovery. Also considered are the impacts that these adaptations have on biochemical and hormonal parameters of mineral homeostasis, the consequences for long-term skeletal health, and the presentation and management of disorders of mineral and bone metabolism.

MicroRNA 874-3p Exerts Skeletal Anabolic Effects Epigenetically during Weaning by Suppressing Hdac1 Expression

Embryonic skeletogenesis and postnatal bone development require the transfer of calcium from the mother to the offspring during pregnancy and lactation. Therefore, bone resorption in the mother becomes elevated during these periods, resulting in significant maternal skeletal loss. There follows an anabolic phase around weaning during which there is a remarkable recovery of the maternal skeleton. However, the mechanism(s) of this anabolic response remain(s) largely unknown. We identified eight differentially expressed miRNAs by array profiling, of which miR-874-3p was highly expressed at weaning, a time when bone loss was noted to recover. We report that this weaning-associated miRNA is an anabolic target. Therefore, an agomir of miR-874-3p induced osteoblast differentiation and mineralization. These actions were mediated through the inhibition of Hdac1 expression and enhanced Runx2 transcriptional activation. When injected in vivo, the agomir significantly increased osteoblastogenesis and mineralization, reversed bone loss caused by ovariectomy, and increased bone strength. We speculate that elevated miR-874-3p expression during weaning enhances bone formation and that this miRNA may become a therapeutic target for conditions of bone loss.