IMR Press / CEOG / Volume 48 / Issue 6 / DOI: 10.31083/j.ceog4806220
Open Access Original Research
Normal distribution of alkaline phosphatase levels during pregnancy
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1 Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel
2 Department of Obstetrics and Gynecology, Meir Medical Center, 4428164 Kfar Saba, Israel
3 Helen Schneider Hospital for Women, Rabin Medical Center, 4941492 Petach Tikva, Israel
4 The Liver Institute, Rabin Medical Center, 4941492 Petach Tikva, Israel
*Correspondence: (Eran Hadar)
Clin. Exp. Obstet. Gynecol. 2021, 48(6), 1393–1399;
Submitted: 8 February 2021 | Revised: 27 July 2021 | Accepted: 28 July 2021 | Published: 15 December 2021
Copyright: © 2021 The Author(s). Published by IMR Press.
This is an open access article under the CC BY 4.0 license (

Background: Previous small-scale studies have reported alkaline phosphatase (ALP) distribution throughout gestation. This retrospective, observational analysis aimed to establish a large-scale, week-specific nomogram of total ALP during pregnancy, and to address physiological parameters that may impact normal ALP secretion throughout pregnancy. Methods: We analyzed ALP levels during pregnancy among 5285 healthy women from various ethnicities, with uncomplicated, term, singleton gestations, who delivered in a single tertiary medical center, from August 2007 to December 2012. Results: We found that normal gestational ALP is significantly elevated during pregnancy compared to a non-pregnant state (132.2 ± 3.0 IU/L vs. 116.7 ± 2.3 IU/L, p < 0.001), and during the third and second trimesters compared to the first trimester (166.4 ± 1.66, 123.7 ± 2.4 and 95.7 ± 1.6 IU/L, respectively; p < 0.001). ALP levels remained unaffected by the modifiers we explored: neonatal sex, neonatal birthweight and maternal age. Conclusion: ALP levels during pregnancy are higher than in the non-pregnant state, gradually increase from the end of the first trimester to term, peaking just prior to delivery. The nomogram presented here can serve as the basis for comparison between a normal population and those with various pregnancy complications, to determine how ALP is associated with adverse pregnancy outcomes.

Alkaline phosphatase
Fig. 1.
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