1. By : Drs Barati Drs Mohammadjafari Drs Masihi Drs aadati Drs Shahbazian DRS Zamanpoor(resident)

2. This study is a retrospective research from 2011/10/10 to 2013/10/21. In this time period 8703 cases underwent the first trimester screening test. The kryptor machine was used for measuring PAPP-A, and putting PAPP-A measurements in the Fetal Medicine Foundation (FMF) software Version: 2.5. All singleton pregnancies with PAPP-A <0.4 Mom were selected and frequency and properties of these mothers were evaluated.

3. In this study frequency of mothers with PAPP-A <0.4 was 1.57%

4. The mean maternal age was 29 years old and the median age was 31 years old

5. A total of 44% of these mothers were nulliparus

6. The mean gestational age at the time of the First trimester screening test was 12 weeks and five days. The mean CRL was 62.10mm.

7. The placental site in 57% of these cases was high (anterior or posterior).

8. The mean of FHR was 162

9. The mean of the NT was 1.7 and 1.45% of the studied population had NT>3

10. The mean of serum β-hCG titrage in these cases was 0.890 Mom.

11. Adjusted risk for trisomy 13 & 18 significantly was more than background risk in mothers with PAPP-A<0.4 whereas this difference was not seen for trisomy 21.