Reference range of Amniotic Fluid Index (AFI) in primigravidae with gestational age from 37 to 42 weeks in a local (Pakistani) population.

Background: Amniotic fluid index (AFI) is a key element in fetal biophysical profile that predicts pregnancy outcome especially near term in primigravidae. The objective of the study was to determine a reference range of AFI in primigravidae of a local population having gestational age from 37 to 42 weeks. Methodology: This study was carried out from January 2019 to December 2019 after approval from Institutional Review Board and Ethical Committee at Shifa International hospital, Islamabad, Pakistan. Applying inclusion and exclusion criteria, a sample of 272 was selected. AFI was calculated for each subject using ultrasound and recorded on a data collection sheet. For the sake of simplicity and clinical relevance, the population was further stratified as term pregnancy (gestational age 37-39 weeks) and postdates pregnancy (40-42 weeks). The reference range of AFI was then calculated using mean ±two standard deviations. Results: The reference range of AFI for gestational age of 37-42 weeks (population as a whole) was 6.8- 17.2 cm. For term pregnancy, it was 7.5- 17.5 cm, and for postdate pregnancy, it was 5.8 to 15.4 cm. Conclusion: The reference range of AFI for gestational age of 37 to 42 weeks in Primigravida women was 6.8 to 17.2 cm. There is a decreasing trend in AFI as pregnancy advances from term to postdate. Keywords:  Amniotic Fluid Index, Gestational age, Primigravida, Reference Range.