Bone mineral changes during pregnancy and lactation

Does adolescent pregnancy affect postmenopausal bone mineral density?

Aim: This study aims to investigate the effect of adolescent pregnancies on bone mineral density in the postmenopausal period and to contribute to this controversial issue. Material and Method: Our study included 70 women at postmenopausal ages. The participants were divided into two groups. Thirty-five women with a history of pregnancy in adolescence were considered group 1, and 35 women without a history of pregnancy were considered group 2. The BMD was measured in the total hip, femoral neck, and lumbar spine. The data were compared using SPSS version 26, and p

The influence of lactation and its duration on bone mineral density in pregnancy and postpartum: A systematic review with meta-analysis

BACKGROUND

There is a plethora of research on the association of parity and duration of lactation with bone mineral density (BMD) during and after pregnancy. However, there are no consensus conclusions on the impact of the duration of lactation on BMD.

AIMS

The aim of this study was to examine the effect of pregnancy, and the duration of lactation on BMD during pregnancy, postpartum phase and 12 months post-delivery.

METHODS

The search terms 'parity' 'lactation' 'BMD' were searched for using PubMed, CINAHL, SCOPUS and EMBASE databases in English language. Two independent reviewers assessed the quality of the included studies using Critical Appraisal Skills Program (CASP) appraisal tool and extracted data on BMD (g/cm²) in Excel. A meta-analysis was conducted with a random effect model using Cochrane Review Manager (Rev 5.4) to analyse the outcome. Heterogeneity was assessed with Chi Squared and I² test. The duration of lactation was grouped into short lactation duration (SLD), ≤4 months and longer lactation duration (LLD) > 6 months.

RESULTS

Twenty-one studies were included in this review with four studies included in the meta-analysis. BMD reduced during pregnancy and lactation. Recovery and net gains in BMD followed weaning. However, at 12 months postpartum, women in the LLD group had significant losses at the lumbar spine while those in the SLD recovered BMD. Between the SLD and LLD groups, the change in BMD was not significant 0.48 g/cm² (95% CI -0.14, 1.10, p = 0.13). BMD losses were greater in primiparous women than multiparous women.

CONCLUSION

Women who breastfed for >6 months had significantly reduced BMD. However, compared to women that breastfed for a ≤4 months there was no significant change in BMD. Further investigation is needed to clarify the association between lactation and BMD in a postpartum population in those women extending breastfeeding beyond one year.

Mechanical Regulation of the Maternal Skeleton during Reproduction and Lactation

PURPOSE OF REVIEW

This review summarizes recently published data on the effects of pregnancy and lactation on bone structure, mechanical properties, and mechano-responsiveness in an effort to elucidate how the balance between the structural and metabolic functions of the skeleton is achieved during these physiological processes.

RECENT FINDINGS

While pregnancy and lactation induce significant changes in bone density and structure to provide calcium for fetal/infant growth, the maternal physiology also comprises several innate compensatory mechanisms that allow for the maintenance of skeletal mechanical integrity. Both clinical and animal studies suggest that pregnancy and lactation lead to adaptations in cortical bone structure to allow for rapid calcium release from the trabecular compartment while maintaining whole bone stiffness and strength. Moreover, extents of lactation-induced bone loss and weaning-induced recovery are highly dependent on a given bone's load-bearing function, resulting in better protection of the mechanical integrity at critical load-bearing sites. The recent discovery of lactation-induced osteocytic perilacunar/canalicular remodeling (PLR) indicates a new means for osteocytes to modulate mineral homeostasis and tissue-level mechanical properties of the maternal skeleton. Furthermore, lactation-induced PLR may also play an important role in maintaining the maternal skeleton's load-bearing capacity by altering osteocyte's microenvironment and modulating the transmission of anabolic mechanical signals to osteocytes. Both clinical and animal studies show that parity and lactation have no adverse, or a positive effect on bone strength later in life. The skeletal effects during pregnancy and lactation reflect an optimized balance between the mechanical and metabolic functions of the skeleton.

Prevalence and correlates of low serum calcium in late pregnancy: A cross sectional study in the Nkongsamba Regional Hospital; Littoral Region of Cameroon

INTRODUCTION

Women from low and middle income countries are generally more likely to have sub-optimal calcium intake. The objective of this study was to assess serum calcium disorders and correlates in late pregnancy.

METHODS

We conducted from December 2018 to April 2019, a cross-sectional hospital-based study targeting pregnant women in late pregnancy in the Nkongsamba Regional Hospital. Data were collected by measurement of parameters (weight, height, blood pressure and foetal birthweight), administration of a semi-structured questionnaire and analysis of blood samples collected from each participant. Absorption spectrophotometry was used to measure serum calcium and albumin concentrations and corrected serum calcium calculated from the Payne's equation. With a statistical significant threshold set at p-value = 0.05, the odds ratio was used as a measure of the strength of association between hypocalcaemia and maternofoetal variables.

RESULTS

We enrolled a total of 354 consenting participants with a mean age of 27.41±5.84 years. The prevalence of hypocalcaemia in late pregnancy was 58.76 [53.42-63.90]%. The rate of calcium supplementation in pregnancy was 57.63[52.28-62.80]% with a mean duration of supplementation of 3.69±1.47 months. When controlled for marital status, age, level of education, and gestational age at delivery, pregnant women with systolic blood pressures below 130 mmHg were significantly less likely to have hypocalcaemia than their counterparts with higher systolic blood pressures (Adjusted Odds Ratio = 0.41[0.18-0.89], p-value = 0.020). No statistically significant associations were found between diastolic blood pressure, body mass index, foetal birth weight and hypocalcaemia.

CONCLUSION

Hypocalcaemia in late pregnancy is highly prevalent (59%) among women accessing reproductive services at the Nkongsamba Regional Hospital. There is also a wide gap in calcium supplementation compared to World Health Organization recommendations. Hypocalcaemia is significantly associated to higher systolic blood pressure in pregnancy. Systematic calcium supplementation and consumption of high calcium containing locally available meals should be encouraged.

The relationship between osteoporosis and body composition in pre- and postmenopausal women from different ethnic groups in China

OBJECTIVE

To investigate the ethnic differences in osteoporosis (OP) and body composition (BC) and their relationship in the Maonan, Mulam, Hmong, and Yao minorities in China.

DESIGN

A total of 860 Maonan, Mulam, Hmong, and Yao women were included in this cross-sectional study. Demographic, health history, and lifestyle information was collected using questionnaires. BC was measured through bioelectrical impedance analysis, and bone mineral density (BMD) was assessed via calcaneal quantitative ultrasound.

RESULTS

Compared with premenopausal women, postmenopausal women exhibited a lower fat-free mass (FFM), muscle mass (MM), limb muscle mass, and T-score but a higher waist-to-hip ratio and prevalence of OP in each minority (p < .05). After adjustment for age, Hmong women displayed the highest body mass index, fat mass, percentage of body fat, visceral fat, and subcutaneous fat contents, while Yao women presented the highest T-scores and lowest prevalence of OP among the four minorities (p < .05). Having a greater number of children and an older age were significant risk factors for OP in all ethnic groups (p < .05, OR > 1). In addition, our results revealed that FFM and MM exhibited exactly the same weak positive relationship with the T-score (r = 0.081, p < .05) after adjusting for menopausal status and age in all of the participants. Furthermore, significant ethnic differences in the relationship between BC and the T-score existed in the four minorities studied here.

CONCLUSIONS

BC and OP prevalence varied by menopausal status and ethnic group, and ethnic-specific relationships between BC and BMD were present in the four minorities. More research is needed to further investigate the ethnic differences in BC, OP, and risk factors for lower BMD to develop targeted prevention strategies to reduce the burden of OP across different ethnic groups in China.

Site-Specific Onset of Low Bone Density and Correlation of Bone Turnover Markers in Exclusive Breastfeeding Mothers

PURPOSE

Lactation often affects calcium metabolism and induces bone loss. Calcium supplementation and a high calcium diet are recommended to prevent bone loss, especially during inadequate calcium intake. Our study aimed at determining bone loss in breastfeeding mothers, and if it occurred, whether it was site specific and there were correlations between serum bone turnover markers.

MATERIALS AND METHODS

Since the 6-month exclusive breastfeeding is usually recommended in several countries, our study examined bone mineral density (BMD) in early (1-2 month), mid (3-4 month)-, and late (5-6 month) lactation compared with nonpregnant, nonlactating control women. Site-specific bone loss was monitored in lumbar vertebrae and femora. Bone turnover markers, that is, C-terminal telopeptide of type 1 collagen and N-terminal propeptide of type 1 collagen (P1NP), were determined by electrochemiluminescence immunoassays.

RESULTS

The onset of bone loss in exclusive breastfeeding mothers was site specific, for example, in the lumbar bone at mid-lactation and in the femoral bone in late lactation. Serum ionized calcium levels in late lactation were lower than the normal levels. In addition, a correlation was found between bone turnover marker, P1NP, and femoral BMD.

CONCLUSIONS

The onset of bone loss in exclusive breastfeeding mothers was site specific, and the lumbar bone was a vulnerable and perhaps better representative site for bone loss detection. It was suggested that the optimal starting time for calcium supplementation should be before the mid-lactation when the bone loss was observed. In addition, the biochemical marker that best predicted the onset of bone loss in lactating women was P1NP.

Prevalence of osteoporosis in the Italian population and main risk factors: results of BoneTour Campaign

BACKGROUND

BoneTour is a campaign conducted throughout the Italian territory for the assessment of Italian people bone status and for the prevention of osteoporosis.

METHODS

A total of 7305 sequential subjects of both sexes were screened, collecting clinical data through the FRAX™ questionnaire, and measuring heel bone stiffness by Quantitative Ultrasonography (QUS). The 10-year risk for hip and major osteoporotic fractures was calculated taking into account personal or family history of fragility fracture, smoking, alcohol abuse, rheumatoid arthritis, prolonged steroids assumption. Additional risk factors were evaluated, including early menopause, poor sunlight exposure, low dietary calcium intake, physical inactivity, number of pregnancies, months of lactation, tobacco cigarettes smoked per year, specific causes of secondary osteoporosis. Through a correlation study, the influence of each factor on the development of osteoporosis was analyzed.

RESULTS

As many as 18 % of women suffer from osteoporosis, as defined by QUS T-score. The calculation of FRAX™ confirmed the weight of the already known risk factors. The correlation study revealed the significance of some additional factors, such as hyperthyroidism, nephrolithiasis, Crohn disease, ulcerative colitis, celiac disease, poor sun exposure, and oophorectomy before age 50.

CONCLUSIONS

The high prevalence of secondary osteoporosis in the Italian population clearly indicates the importance of additional risk factors not yet included in the FRAX™ algorithm, for which preventive measures should be considered. Screening campaigns may allow both early diagnosis and access to treatment.

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.

Adolescent pregnancy; a determinant of bone mineral density in peri-menopausal women?

OBJECTIVE

The present study aims to determine the effects of a history of adolescent pregnancy (AP) on the bone mineral density (BMD) of perimenopausal women.

METHODS

Overall, 240 women aged between 40 and 55 years, with a complaint of oligomenorrhea or amenorrhea not exceeding 1 year in duration, were evaluated. Evaluation included a DEXA scan and a detailed demographic survey for bone health. Comparison was made between women with a history of AP and those without.

RESULTS

In total, 87 women who had a history of AP were compared with 153 women who did not have a history of AP. The study groups did not differ significantly for most of the evaluated demographic factors. Women with a history of AP had higher gravidity and parity. Comparison of T-scores revealed lumbar BMD to be unaffected by AP (P=0.184), whereas femoral BMD was positively influenced by a history of AP (0.78±0.65 vs -1.06±0.67; P=0.042). In covariance regression models, after adjusting for parity and age of first menarche, AP still positively influenced femoral BMD. Without a history of AP, women were at increased risk for osteoporosis of femoral neck (odds ratio, 2.8, 95% CI 1.75-4.8).

CONCLUSIONS

The effects of AP on BMD are not well elucidated. Women with a history of AP had better femoral BMD scores, indicating a possible protective influence of AP on bone health.

BRIEF SUMMARY

Pregnancy during adolescence is associated with a better femoral bone mineral density than pregnancy at an older age. However, the effects did not extend to lumbar spine bone mineral density.

Bone density changes in premature ovarian insufficiency patients who have had term pregnancies

Premature ovarian insufficiency affects 1% of women under the age of 40 and is associated with a hypoestrogenic state, potentially leading to multiple comorbidities including reduced bone density and fertility. An unpredictable ovarian function is observed in 50% of patients with 5-10% being able to achieve a pregnancy. Longitudinal studies have shown a temporary decline in bone mineral density of up to 5% during pregnancy and lactation in healthy women, with the loss of bone density post-partum being proportional to the period of breastfeeding. Effects of pregnancy in women with premature ovarian insufficiency have not been widely documented. Nevertheless, a lower bone mineral density baseline has been observed pre-conceptually, associated with both the hypoestrogenic state of the condition and the possibility that premature ovarian insufficiency was developed prior to achieving peak bone mass. This may suggest that breastfeeding could cause further deterioration in bone mineral density that may not be easy to recover from due to the reduced baseline levels.