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. 2026 Jan 3.
doi: 10.1186/s41043-025-01211-8. Online ahead of print.

Maternal calcium, phosphorus, and supplement intake before and during pregnancy and their association with preterm birth risk: based on a large cohort study

Zifu Wang #  1   2 , Lei Cao #  1 , Yuqing Li  1 , Qinqin Tian  1 , Chenyan Yang  1 , Hongchuan Fu  1 , Yue Fang  3 , Baohong Mao  4 , Liping Yang  5   6
Affiliations
Free article

Maternal calcium, phosphorus, and supplement intake before and during pregnancy and their association with preterm birth risk: based on a large cohort study

Zifu Wang et al. J Health Popul Nutr. .
Free article

Abstract

Background: Preterm birth (PTB) is a global epidemic, defined as delivery before 37 weeks of gestation, and is an important risk factor for neonatal death, morbidity and abnormal childhood development. Premature birth is currently regarded as a complex disease influenced by multiple factors. Common risk factors include nutritional deficiency during pregnancy, maternal obesity, environmental exposure, infection and inflammation, among which maternal nutrition during pregnancy is an important modifiable factor.

Objective: To assess the relationship between maternal dietary calcium, phosphorus intake, and calcium supplement use before and during pregnancy was associated with the risk of PTB in offspring.

Method: This study was a nested case-control study conducted based on a large cohort study. And included pregnant women who were registered at the Perinatal Medicine Center of Gansu Provincial Maternal and Child Health Hospital from March 2018 to March 2019 and whose birth outcomes could be followed up. One-on-one dietary interviews were conducted during pregnancy, and a database was established based on the overall dietary intake levels for subsequent statistical analysis. PTB was defined as the outcome variable, while the intake levels of different substances during pregnancy were set as independent variables. Unconditional logistic regression models estimated the association between nutrient intake and the risk of PTB. Calculating the odds ratio (OR) and its 95% confidence interval (CI) to analyze the impact of different substance intake levels on PTB. Additionally, a restricted cubic spline (RCS) model with multivariable adjustment was applied to excess the non-linear association between dietary magnesium and calcium intake was associated with the risk of PTB.

Result: A total of 8897 pregnant women were included in the study, with 880 assigned to the case group and 8017 to the control group. Multivariate logistic regression analysis showed that low phosphorus intake in the second trimester was associated with an increased risk of PTB (OR = 1.297, CI: 1.020-1.649, P = 0.0341). Furthermore, similar results also exist for non-use of calcium supplements during the third trimester and low calcium intake preconception and during pregnancy. In addition, calcium, phosphorus and calcium supplements have a synergistic effect was associated with the risk of PTB.

Conclusion: During the second and third trimesters of pregnancy, the intake of phosphorus and the use of calcium supplements should be increased. Additionally, to prevent premature birth, the intake of calcium should be increased preconception and during pregnancy. Furthermore, this might lead to the optimization of public health policies or the formulation of guidelines for prenatal nutrition.

Keywords: Calcium; Calcium supplement; Intake; Phosphorus; Pregnancy; Preterm birth.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: Informed consent was obtained from study participants. This research approved by Medical Ethics Committee of Gansu Provincial Maternity and Child-care Hospital [2018] The Ethics Committee of Gansu Provincial Maternity and Child-care Hospital No.(29). All the participants in the study have fully understood the research content, potential risks and benefits, and have voluntarily agreed to take part in the study. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests.

References

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