Maternal serum placental alkaline phosphatase level and risk for preterm delivery

Am J Obstet Gynecol. 1995 Jul;173(1):181-6. doi: 10.1016/0002-9378(95)90187-6.


Objective: The purpose of this study was to determine whether elevated midtrimester serum placental alkaline phosphatase levels are predictive of preterm delivery.

Study design: By use of banked serum specimens from a sample of women who had received maternal serum alpha-fetoprotein screening, placental alkaline phosphatase values for multiples of the median were obtained from 270 mothers who had experienced a preterm delivery and from 1598 mothers of term, appropriate-for-gestational-age infants. Specimens were analyzed for placental alkaline phosphatase by means of a monoclonal antibody enzyme-linked immunosorbent assay. Logistic regression was used to determine whether placental alkaline phosphatase was associated with preterm birth, while potential confounders were controlled for.

Results: Women with placental alkaline phosphatase levels > or = 2.0 multiples of the median were significantly more likely to be delivered of a preterm infant in the current pregnancy compared with women with levels < 2.0 multiples of the median (odds ratio 2.9, 95% confidence interval 2.1 to 3.9). The likelihood of preterm birth increased significantly with higher multiples of the median (p < 0.001).

Conclusion: Women with elevated placental alkaline phosphatase levels are at increased risk for preterm delivery. Additional studies are needed to evaluate the clinical utility of placental alkaline phosphatase testing as a means of identifying mothers at risk for preterm birth.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Alkaline Phosphatase / blood*
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • GPI-Linked Proteins
  • Humans
  • Isoenzymes / blood*
  • Obstetric Labor, Premature / enzymology
  • Obstetric Labor, Premature / etiology*
  • Placenta / enzymology*
  • Pregnancy
  • Pregnancy Trimester, Second
  • Risk Factors


  • GPI-Linked Proteins
  • Isoenzymes
  • Alkaline Phosphatase
  • alkaline phosphatase, placental