The relation between bone mineral density and early pregnancy loss

Effect of parity on bone mineral density: A systematic review and meta-analysis

INTRODUCTION

Parity has been suggested as a possible factor affecting bone health in women. However, study results on its association with bone mineral density are conflicting.

METHODS

PubMed, EMBASE, the Cochrane Library, and Korean online databases were searched using the terms "parity" and "bone mineral density", in May 2016. Two independent reviewers extracted the mean and standard deviation of bone mineral density measurements of the femoral neck, spine, and total hip in nulliparous and parous healthy women.

RESULTS

Among the initial 10,146 studies, 10 articles comprising 24,771 women met the inclusion criteria. The overall effect of parity on bone mineral density was positive (mean difference=5.97mg/cm²; 95% CI 2.37 to 9.57; P=0.001). The effect appears site-specific as parity was not significantly associated with the bone mineral density of the femoral neck (P=0.09) and lumbar spine (P=0.17), but parous women had significantly higher bone mineral density of the total hip compared to nulliparous women (mean difference=5.98mg/cm²; 95% CI 1.72 to 10.24; P=0.006). No obvious heterogeneity existed among the included studies (femoral neck I²=0%; spine I²=31%; total hip I²=0%).

CONCLUSION

Parity has a positive effect on bone in healthy, community-dwelling women and its effect appears site-specific.

Bone mineral density among Korean females aged 20-50 years: influence of age at menarche (The Korea National Health and Nutrition Examination Survey 2008-2011)

To evaluate a possible correlation between bone mineral density (BMD) and age at menarche, the present study used the BMD dataset of the Korea National Health and Nutrition Examination Survey IV-V (KNHANES IV-V). Age at menarche had a small but significant association with BMD of the lumbar spine in premenopausal Korean females, aged 20-50 years.

INTRODUCTION

To investigate any correlation between bone mineral density (BMD) and age at menarche in Korean females using data from the fourth and fifth Korea National Health and Nutrition Examination Survey (KNHANES IV-V; 2008-2011).

METHODS

In total, 37,753 individuals participated in health examination surveys between 2008 and 2011. A total of 5032 premenopausal females aged 20-50 years were eligible. Age, height, weight, and age at menarche were assessed.

RESULTS

Results from the univariate linear regression and analysis of covariance (ANCOVA) indicated that age (per 1 year), height (per 1 cm), weight (per 1 kg), exercise (per 1 day/week), familial osteoporosis history (yes), parity (n = 0 to ≥4), and menarche age distribution were associated with BMD of the total femur, femur neck, and lumbar spine. After stratifying the bone area and adjusting for age, parity, alcohol intake, smoking, exercise, and familial osteoporosis history, no effect was seen for the total femur or femur neck. Age at menarche 16~17 and ≥18 years groups were associated with BMD of the lumbar spine only.

CONCLUSIONS

Age at menarche had a small but significant association with BMD of the lumbar spine in premenopausal Korean females, aged 20-50 years. Females with late menarche may achieve lower peak bone mass at some skeletal sites, which may put them at greater risk for osteoporosis in later life.

Is osteoporosis in postmenopausal female patients related to previous pregnancies and/or miscarriages?

OBJECTIVE

To investigate if osteopenia and osteoporosis in postmenopausal female patients are related to previous pregnancies and/or miscarriages.

PATIENTS AND METHODS

We studied 81 postmenopausal female patients, 40 with osteopenia or osteoporosis and 41 without osteopenia or osteoporosis, carefully matched for age (control group). In the two groups, the presence or not of osteopenia, osteoporosis, or both, were analyzed and compared with the number of childbirths and/or miscarriages.

RESULTS

Overall, no statistical difference was found among the 40 patients with one, two, three or more than three childbirths and osteopenia or osteoporosis compared with the control group (p=0.5363, p=0.5782, p=0.0763, p=0.1931, respectively). Similarly, no differences were found between the osteopenia/osteoporosis group and the control group in relation to previous one, two, three or more than three miscarriages. When both childbirths and miscarriages were added together (three, four, five, six, more than six), again no statistical difference was found between the osteopenia/osteoporosis group and the control group.

CONCLUSIONS

In postmenopausal women, the obstetric history of previous childbirths and/or miscarriages, independent of the number, did not seem to be a risk factor for osteopenia or osteoporosis.

Effect of parity on phalangeal bone mineral density in post-menopausal Sri Lankan women: a community based cross-sectional study

There is paucity of studies related to parity and bone mineral density in South Asian countries. We recruited 713 healthy, community dwelling post-menopausal women from seven provinces in Sri Lanka for this survey. The number of pregnancies, including miscarriages beyond 20 weeks of gestation, was recorded. Women with diseases and those who have taken drugs that can affect bone mineral density (BMD) were excluded (n = 15). Phalangeal BMD and bone mineral content (BMC) were measured using AccuDEXA in 713 women. Mean (SE) BMD of nulliparous women (n = 32), women with one to two pregnancies (n = 284), three to four pregnancies (n = 290) and more than four pregnancies (n = 107) were 0.437(0.014), 0.454(0.005), 0.455(0.005) and 0.417(0.006) g/cm(2), respectively (P < 0.001). Corresponding mean (SE) BMCs were 1.30(0.063), 1.41(0.021), 1.43(0.022) and 1.32(0.033) g, respectively (P < 0.001). Women with more than four pregnancies were older and lighter when compared with other groups. When results were adjusted for current age and current weight, differences in mean BMD and BMC between groups became non-significant. BMD of nulliparous women remained low in all analyses. We report a significant difference in unadjusted phalangeal BMD in women categorized according to their parity. Women with one to four pregnancies had the highest phalangeal BMD and BMC, while multi-parous (more than four pregnancies) and nulliparous women had lower values. However, in an adjusted analysis, the differences in BMD and BMC were partially explained by the differences of age and body weight between the groups and the unique effect of parity was difficult to determine. Women with lower BMD may have a higher risk of future fractures.

The association of pregnancy history with areal and volumetric bone mineral density in adolescence

INTRODUCTION

Studies demonstrate that pregnancy may interfere with bone mineral density. Adolescence is a crucial time of life for bone mass acquisition and there are some questions as to the influence of pregnancy on bone mass at this age.

OBJECTIVE

To evaluate the association between pregnancy history and areal (BMD) and volumetric (vBMD) bone mineral density in adolescence.

SUBJECTS AND METHODS

A cross-sectional study of 119 adolescents ranging from 12-20 years of age was conducted; 30 of these girls had a history of full-term pregnancy. The adolescents were selected during a routine visit to the Adolescent Gynecology Outpatient Facility, completed a questionnaire, and had a physical examination to evaluate weight, height and Tanner stage. Bone mineral densitometry of the lumbar spine (L(1)-L(4)) and total body (TB) was performed to measure bone mineral density and body composition.

RESULTS

The mean measurements of the area, bone mineral content (BMC), BMD and vBMD of L(1)-L(4) and the area, BMC and BMD of TB were not significantly different between adolescents with and without a pregnancy history, stratified by chronologic and gynecologic age. The percentage of adolescents with altered Z-scores was similar in both groups, and the prevalence ratio showed no association between pregnancy history and low bone mass (PR=0.52; CI 0.04-6.07). Upon multiple regression analysis, body mass index (BMI) and lean body mass (LBM) were the main factors associated with lumbar spine and total body measurements. Pregnancy history was inversely associated with areal BMD of L(1)-L(4) (R (2)=0.04) and vBMD of L(1)-L(4) (R (2)=0.04), accounting for only 4% variation in the lumbar spine.

CONCLUSION

These data suggest that adolescent pregnancy seems to exert no significant influence on the acquisition of bone mass and does not appear to represent a risk factor for osteoporosis in the future.

Effect of pregnancy on bone mineral density in healthy women

Despite numerous studies and case reports of changes in bone mineral density (BMD) during pregnancy, the postpartum, and lactation, controversy exists regarding the time course of BMD changes and recovery to baseline levels. The degree to which pregnancy affects BMD long-term remains unclear. Several influencing factors, including breast-feeding, length of amenorrhea after pregnancy, and parity, have been studied with respect to changes in BMD in healthy women. We conducted the first systematic review of its kind on this topic and evaluated the 23 identified citations according to the U.S. Preventive Services Task Force rating scale. Six studies qualified as Level II-2, 12 were Level II-3, and 5 were Level III. There seems to be good evidence that calcium is mobilized from the maternal skeleton to that of the developing fetus during pregnancy. However, the eventual return of BMD to prepregnancy values suggests that maternal bone loss may not be permanent. Results from the studies that specifically evaluated the effect of lactation on BMD were varied, ranging from a decrease in BMD to no change. Of the studies that evaluated the effect of parity on BMD, none found an association linking a greater number of pregnancies to greater decreases in BMD. Pregnancy-associated osteoporosis seems to be uncommon, based on the limited published reports. Overall, no long-term adverse clinical effects have been noted in healthy women who had at least one ongoing pregnancy, despite the good evidence that some bone loss does occur soon after delivery. Additional longitudinal studies need to be undertaken to provide more definitive information on the effects of pregnancy on BMD and risk of osteoporosis later in life.

Calcium in pregnancy and lactation

Pregnancy and lactation are periods of high calcium requirement. This review highlights recent advances in our understanding of calcium and bone metabolism during human pregnancy and lactation and discusses the findings in relation to the calcium nutrition of the mother. The evidence indicates that pregnancy and lactation are characterized by physiological adaptive processes that are independent of maternal calcium intake and that provide the calcium necessary for fetal growth and breast-milk production without requiring an increase in maternal calcium intake. There are firm data that demonstrate that a low calcium intake during lactation does not lead to impaired lactational performance or to exaggerated bone loss. However, more research is required to define whether a low calcium intake prior to or during pregnancy can have deleterious effects on reproductive and lactational performance, and on the long-term health of the mother and child.

The role of calcium in health and disease

Skeletal fragility at the end of the life span (osteoporosis) is a major source of morbidity and mortality. Adequate calcium intake from childhood to the end of the life span is critical for the formation and retention of a healthy skeleton. High intakes of calcium and vitamin D potentiate the bone loss prevention effects of hormone replacement therapy in postmenopausal women. Pregnancy and lactation are not risk factors for skeletal fragility, although lactation is associated with a transient loss of bone that cannot be prevented by calcium supplementation. Low calcium intake has been implicated in the development of hypertension, colon cancer, and premenstrual syndrome, and it is associated with low intakes of many other nutrients. Encouragement of increased consumption of calcium-rich foods has the potential to be a cost-effective strategy for reducing fracture incidence later in life and for increasing patients' dietary quality and overall health.

Multiparity and bone mass

OBJECTIVE

To investigate the influence of multiparity on bone mass of the axial skeleton in a population of women of high parity.

DESIGN

Open study of Omani women.

SETTING

Medical physics department and clinical physiology department of a third degree referral (university) hospital.

PARTICIPANTS

A consecutive series of 159 normal women referred with low back pain over a period of six months.

RESULTS

The bone mineral density was measured with dual-photon absorptiometry and the mean was found to be 0.984 (+/-0.166) (+/- SD) g cm-2. The age ranged from 20 to 70 years with a mean age of 43.4 (+/- 12.5) years. The number of children per woman ranged from 0 to 14 with a mean of 5.1 (+/- 3.5). There was no statistically significant influence of the number of children per woman on bone mineral density but there was a strong correlation with age and body size variables.

CONCLUSION

Multiparity does not influence lumbar spine bone mineral density in normal women.

Osteoporosis in pregnancy

Osteoporosis has long been described in pregnant women who developed vertebral fractures in the last trimester or shortly after delivery without underlying disorders. However, this condition appears to be relatively rare and the clinical features, associated metabolic abnormalities and a pathological mechanism have not been fully established. This paper reviews available data on osteoporosis and pregnancy and briefly discusses the relationship between pregnancy and bone mass, calcium homeostasis, systemic skeletal hormones and local factors to help explain the pathophysiology of this unique disorder.

Postmenopausal bone loss in Japanese women

OBJECTIVES

Our purpose was to detect anatomic variations in postmenopausal bone loss and to determine the risk factors most affecting bone mass in Japanese women.

METHODS

One hundred sixty-six Japanese women (54 premenopausal and 112 postmenopausal), aged 40-68 years, were enrolled in the study. Bone mineral densities (BMD) of the lumbar spine (L2-4) and total body were measured by dual energy X-ray absorptiometry and the results were subjected to statistical analysis.

RESULTS

Among the various sites studied, the lumbar spine (L2-4) showed the fastest bone loss after menopause. Multiple regression analysis indicated that two factors, number of years since the menopause and body mass index (BMI), affected lumbar spine (L2-4) BMD.

CONCLUSION

Measurement of lumbar spine (L2-4) BMD is suitable for evaluating postmenopausal osteoporosis. The risk factors for postmenopausal bone loss were a long period after menopause and a low BMI.