Objective To systematically evaluate the correlation between vitamin D deficiency in early pregnancy and the outcome of preterm birth.Method PubMed,Embase,the Cochrane Library,Web of Science,Ebsco,CBM,CNKI and Wanfang Data databases were searched to collect cohort studies and case-control studies on the correlation between vitamin D deficiency in early pregnancy and preterm birth outcomes,and the retrieval time was from the establishment of the database to June 2019.Two researchers independently reviewed the literature,extracted the data and evaluated the risk of bias in the included studies.RevMan 5.3 software was used for Meta analysis.Result A total of 6 cohort studies and 3 nested case-control studies were included.A total of 30 891 newborns were included,including 1 912 premature infants.3 Chinese articles and 6 English articles were reviewed including three studies from China,three from North America,two from Europe and one from Australia.The diagnostic criteria for vitamin D deficiency and preterm birth were similar in these studies.After adjusting for age,race and other confounding factors,Meta-analysis results showed that vitamin D deficiency in early pregnancy did not increase the risk of preterm birth (OR =1.04,95％ CI 0.90 ～ 1.20,P =0.63).Subgroup analysis were conducted according to the study type,measurement method and regional population,and the results were consistent with the overall results.No significant publication bias was found in the meta-analysis results.Conclusion Current evidence suggests that vitamin D deficiency in early pregnancy has no significant influence on preterm birth.