Related Experiment Video
Updated: Aug 6, 2026
Continuous Telemetric In Utero Tracheal Pressure Measurements in Fetal Lambs
Published on: December 22, 2023
Second-trimester amniotic fluid index and single deepest pocket percentile curves in a Turkish singleton cohort: a
Fulya Sultan Karaduman1, Numan Cim1, Meltem Caliskan1
1Department of Obstetrics and Gynecology, Haseki Training and Research Hospital, University of Health Sciences, Uğur Mumcu Mah. Belediye Sk. No:7, Sultangazi, Istanbul 34265, Turkey.
Objective:
To construct gestational age-specific P3-P97 percentile curves for amniotic fluid index (AFI) and single deepest pocket (SDP) in healthy singleton pregnancies between 14 and 28 weeks in a Turkish cohort, and compare them with international references.
Study Design:
A prospective cross-sectional study at Haseki Training and Research Hospital, Istanbul, between February 2025 and February 2026. We included 507 healthy singleton pregnancies (14-28 weeks), each with one measurement. AFI and SDP were obtained during routine ultrasonography by two perinatologists under senior supervision, all using a shared written protocol. P3-P97 percentiles were generated empirically per gestational age and smoothed with polynomial regression. LMS modeling served as secondary verification.
Results:
AFI rose from 105 mm at 14 weeks to 163 mm at 28 weeks (r = 0.609, p < 0.001), and SDP rose from 38 mm to 55 mm (r = 0.581, p < 0.001). AFI P50 values were up to 2.3 cm (median 1.7 cm) greater than the classic Moore-Cayle reference (weeks 16-28). Neither BMI nor placental location was significantly associated with AFI (p = 0.099 and p = 0.771, respectively). Inter-observer reliability was very good for both AFI (ICC[A,1] = 0.976) and SDP (ICC[A,1] = 0.920).
Conclusion:
This study provides second-trimester AFI and SDP P3-P97 reference curves in a Turkish cohort. AFI values were higher than those in classic international nomograms, suggesting that older reference charts may not be applicable to contemporary clinical settings and may influence classification in borderline cases.
