Detection of Fetal Fraction During Noninvasive Prenatal Screening (NIPS) in HIV-Infected Pregnant Women [22]

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To describe the reliability of Non Invasive Prenatal Screening (NIPS) in HIV infected pregnant women. NIPS analyzes cell free fetal DNA which circulates in maternal plasma but originates from the placenta and is quantitated as “fetal fraction” (FF). Sensitivity of NIPS increases with FF. In certain populations NIPS reliability decreases, with obesity as the strongest factor negatively associated with FF. Additional variables including PAPP-A and smoking have been shown to affect FF. Our study aims to determine if immune system alterations such as HIV or antiretroviral medications impact FF.


A 2:1 matched case-control study was carried out comparing 15 HIV infected pregnant women to 30 without HIV undergoing NIPS. Variables such as BMI, ethnicity, medical comorbidities, toxic habits, fetal CRL, serum analytes, FF, and pregnancy outcomes were compared. Immune status and antiretroviral medications were evaluated in correlation with FF in HIV infected patients.


HIV infected patients receiving integrase inhibitors (INI) had lower mean FF than those without INI—4.93 (SD 2.20) versus 15.7 (SD 5.43) (P=<.01). NIPS was invalid for three HIV infected patients – all of whom were receiving INI - due to low FF. HIV infected patients with an undetectable viral load (VL) at NIPS had a significantly lower median FF compared to those with detectable VL (P=.01).


Integrase inhibitors may play a role in reliability of NIPS in HIV infected women, as reflected by lower FF for patients taking INI. Further study is needed to fully elucidate the mechanism for INI and decreased FF.

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