464: Fetal tachycardia is an independent risk factor for chromosomal anomalies during first trimester genetic screening

Abstract

There is conflicting information regarding the association of abnormal fetal heart rate (FHR) and chromosomal anomalies in the first trimester of pregnancy. This may be related to prior studies that did not control for potential confounding factors. This study examines the relationship between FHR and chromosomal anomalies between 10 to 14 weeks of gestation. This retrospective cohort study included all women who had first-trimester genetic screening between November 2011 and December 2014 at a single institution. The 95th percentile for nuchal translucency (NT) measurement was calculated for each gestational week. A multivariable logistic regression analysis was performed to determine if a FHR ≥ 170 beats per minute (bpm), derived from a ROC curve, is an independent risk factor for chromosomal anomalies while controlling for advanced maternal age (AMA;>35 years old), gestational age (GA) at scan, crown-rump length (CRL), maternal BMI, nuchal septations, NT>95th percentile and multiple pregnancies. FHR ≥ 170 bpm was seen in 7% (228/3026) and chromosomal anomalies were present in 1.0% (33/3275) of the study population. A greater proportion of fetuses with chromosomal anomalies had FHR ≥ 170 bpm compared to those with normal chromosomes (29% vs. 6.8%; p<0.01). FHR ≥ 170 bpm was an independent risk factor for chromosomal anomalies [adjusted Odd Ratio (aOR): 4.9; 95% CI: 1.3-18.4; p=0.02) after controlling for AMA (aOR: 11.9; 95% CI: 3.1-45.2, p<0.001), NT>95th percentile (aOR: 17.1; 95% CI: 4.3-68.2, p<0.001), nuchal septations (aOR: 53.4; 95% CI: 7.6-371.9 p<0.001), GA at scan (aOR: 3.3; 95% CI: 1.1-10.7 p=0.04), multiple pregnancies (p=1), maternal BMI (p=0.3), and CRL (p=0.1). Chromosomal anomalies included trisomy 21 (n = 17), trisomy 18 (n = 4), trisomy 13 (n = 2), Turner syndrome (n = 1), Noonan syndrome (n = 3), translocations (n = 2), deletions (n = 2), and others (n = 2). FHR ≥ 170 bpm is a risk factor for chromosomal anomalies during first-trimester genetic screening, independent of increased NT, nuchal septations and maternal age. Thus, early fetal tachycardia should increase the suspicion for chromosomal anomalies. To the extent that fetal tachycardia may also be an independent factor from biochemical markers, consideration could be given to add FHR to the first trimester genetic screening.