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Meta-Analysis
. 2021 Mar 29;11(1):7081.
doi: 10.1038/s41598-021-86445-2.

Systematic review and meta-analysis of female lifestyle factors and risk of recurrent pregnancy loss

Ka Ying Bonnie Ng  1   2 , George Cherian  2 , Alexandra J Kermack  1   2 , Sarah Bailey  2 , Nick Macklon  3   4 , Sesh K Sunkara  5 , Ying Cheong  6   7   8
Affiliations
Meta-Analysis

Systematic review and meta-analysis of female lifestyle factors and risk of recurrent pregnancy loss

Ka Ying Bonnie Ng et al. Sci Rep. .

Abstract

It is known that lifestyle factors affect sporadic miscarriage, but the extent of this on RPL (recurrent pregnancy loss) is less well known. A systematic review and meta-analysis was performed to assess the associations between lifestyle factors and RPL. Studies that analysed RPL in the context of BMI, smoking, alcohol and caffeine intake were included. The primary and secondary outcomes were odds of having RPL in the general population and odds of further miscarriage, respectively. Underweight and women with BMI > 25 are at higher odds of RPL in the general population (OR 1.2, 95% CI 1.12-1.28 and OR 1.21, 95% CI 1.06-1.38, respectively). In women with RPL, having BMI > 30 and BMI > 25 has increased odds of further miscarriages (OR 1.77, 95% CI 1.25-2.50 and OR 1.35, 95% CI 1.07-1.72, respectively). The quality of the evidence for our findings was low or very low. Being underweight and BMI > 25 contributes significantly to increased risk of RPL (general population). BMI > 25 or BMI > 30 increases the risk of further miscarriages (RPL population). Larger studies addressing the effects of alcohol, cigarette smoking and caffeine on the risk of RPL with optimisation of BMI in this cohort of women are now needed.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
PRISMA flow diagram detailing search results.
Figure 2
Figure 2
Forest plot demonstrating meta-analysis of the effect of BMI on RPL and further miscarriage. (a) BMI > 25 significantly increases risk of RPL in general population. (b) BMI > 30 significantly increases risk of further miscarriage in RPL population. (c) BMI > 25 significantly increases risk of further miscarriage in RPL population. (d) Underweight BMI significantly increases risk of RPL in general population. (e) Underweight BMI has no effect on risk of further miscarriage in RPL population. 95% CI = 95% confidence interval; M-H = Mantel–Haenszel statistical test.
Figure 3
Figure 3
Forest plot demonstrating meta-analysis of the effect of lifestyle factors on RPL. (a) Cigarette smoking does not significantly increase risk of RPL in general population. (b) Alcohol intake does not significantly increase risk of RPL in general population. (c) Caffeine intake does not significantly increase risk of RPL in general population. 95% CI = 95% confidence interval; M-H = Mantel–Haenszel statistical test.
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