Preconception underweight impact on postnatal osteoporotic fracture: a retrospective cohort study using Japanese
Kayoko Kaneko1, Maiko Suto2, Eiko Miyagawa3
1Division of Maternal Medicine, Center for Maternal-Fetal, Neonatal and Reproductive Medicine, National Center for Child Health and Development, Tokyo, Japan. kaneko-ky@ncchd.go.jp.
Insights
Preconception underweight in Japanese women is linked to an increased risk of postpartum osteoporotic fractures. Maintaining a healthy weight before pregnancy is crucial for maternal bone health and infant care.
Area of Science:
- Reproductive Health
- Bone Metabolism
- Public Health
Background:
- Undernutrition and underweight are recognized risk factors for osteoporosis.
- Improving the health of underweight young women in Japan is a significant medical concern.
- Limited research exists on the link between preconception underweight and postpartum osteoporotic fractures.
Purpose of the Study:
- To investigate the association between preconception underweight and the incidence of osteoporotic fractures within two years postpartum.
- To analyze fracture risk in relation to body mass index (BMI) before pregnancy.
Main Methods:
- Retrospective cohort study using a Japanese nationwide claims database (JMDC Inc.).
- Analysis of data from 16,684 mothers delivering their first singleton babies (January 2006 - December 2020).
- Osteoporotic fractures defined by disease codes and medical procedures; preconception BMI (12-36 months pre-delivery) as exposure; Kaplan-Meier curves and Cox regression analyses used.
Main Results:
- Fifty-one women (0.31%) experienced osteoporotic fractures within two years postpartum.
- Rib fractures constituted over 80% of cases, with ~65% occurring after the first postpartum year.
- Preconception underweight (BMI < 18.5 kg/m²) was significantly associated with postpartum osteoporotic fractures.
Conclusions:
- Preconception weight management is vital for enhancing postpartum quality of life.
- Adequate preconception weight may positively impact subsequent bone health.
- Optimizing maternal weight before pregnancy can contribute to a better neonatal care environment.
Background:
Undernutrition and underweight are osteoporosis risk factors. Therefore, improving the health of underweight young women in Japan is an important medical issue. However, few studies have evaluated the association between being preconception underweight and postnatal osteoporotic fractures in young women.
Methods:
This retrospective cohort study used a Japanese nationwide claims database (JMDC Inc.) to evaluate the effect of preconception underweight on the incidence of osteoporotic fracture within two years after delivery. Data from 16,684 mothers who delivered their first singleton babies between January 2006 and December 2020 were analysed. The combination of disease codes of fractures at sites associated with osteoporosis and medical procedures for fractures was defined as the incidence of osteoporotic fractures, whereas the body mass index (BMI) recorded 12-36 months before delivery was used as the exposure. We estimated the incidence of osteoporotic fractures by BMI category using a Kaplan-Meier curve and examined the fracture risk using Cox hazard regression analyses.
Results:
Fifty-one women (0.31%) were affected by osteoporotic fractures within two years of delivery. More than 80% of these were rib fractures, and approximately 65% of fractures occurred after the first year postpartum. Preconception underweight (BMI < 18.5 kg/m2) was significantly associated with the incidence of postpartum osteoporotic fractures. There was no significant association between low BMI and postnatal fractures, as analysed via multiple categorical logistic regression analysis.
Conclusion:
Appropriate control of preconception weight might be critical to improving the postpartum quality of life, subsequent bone health, and neonatal care environment.
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