Parity and osteoporotic fracture risk in postmenopausal women: a dose-response meta-analysis of prospective studies
- 423 Downloads
The present dose-response meta-analysis shows linearly decreased hip fracture (HF) risk and nonlinearly decreased osteoporotic fracture (OF) risk associated with increasing number of parity of up to five live births among postmenopausal women.
Epidemiological reports suggest that parity is associated with reduced OF risk among women. However, these findings are controversial. Here, we present a meta-analysis of prospective studies of parity in relation to OF risk.
We performed systematic searches using Medline and Embase from January 1, 1966, to December 31, 2014, with limits of language in English and prospective study design. Relative risks (RRs) and confidence intervals (CIs) were derived mainly using random-effects models. Categorical, dose-response, heterogeneity, publication bias, and subgroup analyses were conducted.
We analyzed 10 articles of 19 independent reports from 1966 to 2014, comprising a total of 217,295 participants and 26,525 cases of OF. Compared to nulliparous women, the OF and HF risks of parous women with at least one live birth were reduced by 11 % (95 % confidence interval (CI) 3–19 %; I 2 = 77.1 %, p < 0.001) and 26 % (95 % CI 17–35 %; I 2 = 19.5 %, p = 0.287), respectively. Representative nonlinearly and linearly inverse dose-response associations were found between parity (range of 0–6) and OF risk (p nonlinearity = 0.0163; I 2 = 79.7 %, p < 0.001), and between parity (range of 0–5) and HF risk (p nonlinearity = 0.054; I 2 = 76.5 %, p < 0.001), respectively. The lowest risk reduction for OF of 25 % (95 % CI 16–33 %) was observed for five live births. And, the summary risk reduction for HF was 12 % (95 % CI 9–15 %) for each one increased live birth.
We found that increasing number of parity is associated with linearly reduced HF risks among women. The association between parity of six or more live births and HF risks should be studied further in future.
KeywordsFracture Hip Meta-analysis Osteoporosis Parity Women
The work has been supported by the National Science Foundation of China (grant no. 81573235), Fundamental Research Funds for the Central Universities (grant no. HUST:2014TS048), Health and Family Commission of Wuhan Municipality (grant no. WG15D20), and Wuhan Jiangan District Science and Technology Bureau (grant no. 20114111904). We convey apology to authors of studies with similar interest while not involved in our analyses due to language limitation. The funding sources had no role in the study design, data collection, analysis, data interpretation, or the writing of the report.
Compliance with ethical standards
Conflicts of interest
Qi Wang, Qin Huang, Yun Zeng, Jiao Jun Liang, Shu Yun Liu, Xue Gu, and Jun An Liu declare that they have no conflict of interest.
- 19.Stroup DF, Berlin JA, Morton SC, Olkin I, Williamson GD, Rennie D, Moher D, Becker BJ, Sipe TA, Thacker SB (2000) Meta-analysis of observational studies in epidemiology: a proposal for reporting. Meta-analysis Of Observational Studies in Epidemiology (MOOSE) group. JAMA 283:2008–2012PubMedCrossRefGoogle Scholar
- 20.Wells G, Shea B, O'Connell D, Peterson J, Welch V, Losos M, Tugwell P (2009) The Newcastle-Ottawa Scale (NOS) for assessing the quality of nonrandomised studies in meta-analyses. Ottawa Health Research Institute, OttawaGoogle Scholar
- 24.Osini N, Bellocco R, Greenland S (2006) Generalized least squares for trend estimation of summarized dose-response data. Stata J 6:40–57Google Scholar
- 34.Hsueh WA, Billig H (1995) Ovarian hormone synthesis and mechanism of action. In: DeGroot LJ (ed) Endocrinology. Saunders, Philadelphia, PA, USA, pp 2019–2030Google Scholar
- 35.Strauss JF, Gafvels M, King BF (1995) Placental Hormones. In: DeGroot LJ (ed) Endocrinology. Saunders, Philadelphia, PA, USA, pp 2171–2206Google Scholar
- 38.Johnell O, Gullberg B, Kanis JA, Alander E, Elffors L, Dequeker J, Dilsen G, Gennari C, Lopes Vaz A, Lyritis G, Mazzuoli G, Miravet L, Passeri M, Cano PR, Rapado A, Ribot C (1995) Risk factors for hip fracture in European women: the MEDOS Study. Mediterranean Osteoporosis Study. J Bone Miner Res 10:1802–1805PubMedCrossRefGoogle Scholar
- 53.Cummings SR, Rubin SM, Black D (1990) The future of hip fractures in the United States. Numbers, costs, and potential effects of postmenopausal estrogen. Clin Orthrop 252:163–166Google Scholar
- 56.Hedlund R, Lindgren U, Ahlbom A (1987) Age- and sex-specific incidence of femoral neck and trochanteric fractures. An analysis based on 20,538 fractures in Stockholm County, Sweden, 1972-1981. Clin Orthop Relat Res 222(222):132–139. doi: 10.1097/00003086-198709000-00018