Malgorzata Mlynarczyk

The clinical significance of an estimated fetal weight below the 10th percentile: a comparison of outcomes of <5th vs 5th–9th percentile

BACKGROUND: The association between small‐for‐gestational‐age (birthweight <10th percentile for gestational age) and neonatal morbidity is well established. Yet, there is a paucity of data on the relationship between suspected small for gestational age (sonographic‐estimated fetal weight <10th percentile) at 2 thresholds and subsequent neonatal morbidity. OBJECTIVE: The objective of this study was to determine the relationship between sonographic‐estimated fetal weight <5th percentile vs 5–9th percentile and neonatal morbidity. STUDY DESIGN: This retrospective study involved 5 centers and included nonanomalous, singletons with sonographic‐estimated fetal weight <10th percentile for gestational age who delivered from 2009–2012. Composite neonatal morbidity included respiratory distress syndrome, proven sepsis, intraventricular hemorrhage grade III or IV, necrotizing enterocolitis, thrombocytopenia, seizures, or death. Odd ratios were adjusted for center, maternal age, race, body mass index at first visit, smoking status, use of alcohol, use of drugs, and neonatal gender. RESULTS: Of 834 women with suspected small‐for‐gestational‐age fetuses, 513 (62%) had sonographic‐estimated fetal weight <5th percentile, and 321 (38%) had sonographic‐estimated fetal weight of 5–9th percentile for gestational age. At delivery, 81% of women with a suspected small‐for‐gestational‐age fetus had a confirmed small‐for‐gestational‐age fetus. In the group with a sonographic‐estimated fetal weight <5th percentile, 59% of neonates had birthweight <5th percentile; in the group with a sonographic‐estimated fetal weight 5–9th percentile, 41% had birthweight <5th percentile, and 36% had birthweight at 5–9th percentile. Neonatal intensive care unit admission differed significantly for those fetuses at <5th percentile (29%) compared with those fetuses at 5–9th percentile (15%; P<.001). The composite neonatal morbidity among the sonographic‐estimated fetal weight <5th percentile group was higher than the sonographic‐estimated fetal weight of 5–9th percentile group (31% vs 13%; adjusted odds ratio, 2.41; 95% confidence interval, 1.53–3.80). Similar findings were noted when the analysis was limited to sonographic‐estimated fetal weight within 28 days of delivery (adjusted odds ratio, 2.22; 95% confidence interval, 1.34–3.67). CONCLUSION: Eight of 10 suspected small‐for‐gestational‐age fetuses had birthweight <10th percentile for gestational age; the prediction of actual birthweight was more accurate in the <5th percentile group. Neonates with sonographic‐estimated fetal weight of <5th percentile were more likely to be admitted to the neonatal intensive care unit and have complications than were those neonates with sonographic‐estimated fetal weight of 5–9th percentile.

Uncomplicated Pregnancies and Ultrasounds for Fetal Growth Restriction: A Pilot Randomized Clinical Trial.

Objective The purpose of this multicenter pilot study was to determine the feasibility of randomizing uncomplicated pregnancies (UPs) to have third trimester ultrasonographic exams (USE) versus routine prenatal care (RPNC) to improve the detection of small for gestational age (SGA; birth weight < 10% for GA). Material and Methods At three referral centers, 50 UPs were randomized after gestational diabetes was ruled out. Women needed to screen, consenting, and loss to follow-up was ascertained, as was the detection rate of SGA in the two groups. Results During the study period at the three centers, there were 7,680 births, of which 64% were uncomplicated. Of the 234 women approached for randomization, 36% declined. We recruited 149 women and had follow-up delivery data on 97%. The antenatal detection rate of SGA in the intervention group was 67% (95% confidence intervals 31–91%) and 9% (0.5–43%) in control. Conclusion The pilot study provides feasibility data for a multicenter randomized clinical trial to determine if third trimester USE, compared with RPNC, improves the detection of SGA and composite neonatal morbidity.

Changes in prenatal testing trends after introduction of noninvasive prenatal testing.

INTRODUCTION: Noninvasive prenatal testing is a highly sensitive and specific prenatal screening method that offers significant advantages over traditional testing modalities such as first-trimester combined screen, chorionic villus sampling (CVS), and amniocentesis. We report noninvasive prenatal testing uptake and the changes in first-trimester combined screen, CVS, and amniocentesis testing after noninvasive prenatal testing introduction in a single academic practice. METHODS: Average monthly procedure rates for four prenatal tests (noninvasive prenatal testing, first-trimester combined screen, CVS, and amniocentesis) were compared retrospectively over four time periods: 1) before noninvasive prenatal testing introduction (April–July of 2009, 2010, and 2011, to account for seasonal variation); 2) the first 4 months of noninvasive prenatal testing in clinical practice (April 2012 to July 2012); 3) 4 months immediately preceding the formal American College of Obstetricians and Gynecologists’ statement on noninvasive prenatal testing (August 2012 to November 2012); and 4) 4 months after the American College of Obstetricians and Gynecologists’ recommendation of noninvasive prenatal testing (December 2012 to March 2013). Data were also normalized per 100 targeted ultrasound scans to control for fluctuations in patient visits. RESULTS: A total of 977 noninvasive prenatal testing, 2,817 first-trimester combined screen, 100 CVS, and 507 amniocenteses were performed during the study period. Once available, noninvasive prenatal testing showed high uptake, increasing over the study intervals by 17.4% per 100 targeted ultrasound scans. First-trimester combined screen significantly decreased after noninvasive prenatal testing introduction, decreasing by 47.5% per 100 targeted ultrasound scans over the study intervals. The rate of CVS and amniocentesis also significantly decreased after the introduction of noninvasive prenatal testing, decreasing by 90.4% and 63.5% per 100 targeted ultrasound scans over the study intervals, respectively. CONCLUSIONS: Noninvasive prenatal testing was quickly adopted by our clinic population and significantly decreased other screening and diagnostic methods in a short period of time.

Differential Effects of First-Trimester Screening Programs on Chorionic Villus Sampling

INTRODUCTION: The American College of Obstetricians and Gynecologists recommends that all women be offered screening for fetal aneuploidy regardless of maternal age. Two first-trimester screening programs are the first-trimester combined screen and noninvasive prenatal testing with positive screens followed up with invasive methods such as chorionic villus sampling (CVS). We show here the differing effects on CVS procedure rates after the introduction of first-trimester combined screen and noninvasive prenatal testing in a single practice. METHODS: Chorionic villus sampling and first-trimester combined screen procedures for a 9-year period were recorded from clinic billing information and evaluated 1) before first-trimester combined screen was offered (July 2004 to February 2006); 2) after first-trimester combined screen introduction but before noninvasive prenatal testing (March 2006 to February 2012); and 3) after noninvasive prenatal testing introduction (March 2012 to June 2013). Data were normalized per 1,000 targeted ultrasound scans to account for fluctuations in patient number and compared using analysis of variance. RESULTS: A total of 9,780 first-trimester combined screen and 608 CVS procedures were recorded during the 9-year study period. First-trimester combined screen peaked in 2009–2010 with 1,836 procedures but declined by 48.1% to 952 procedures after introduction of noninvasive prenatal testing. Monthly first-trimester combined screen and monthly first-trimester combined screen per 1,000 targeted ultrasound scans also significantly decreased postnoninvasive prenatal testing. During the same period, CVS increased from 55 to 100 procedures in 2007–2008 (81.8% increase from prefirst-trimester combined screen levels) but decreased to 22 procedures in 2012–2013 (78.0% decrease postnoninvasive prenatal testing). Furthermore, CVS procedures per 1,000 targeted ultrasound scans significantly increased after first-trimester combined screen but significantly decreased after noninvasive prenatal testing. CONCLUSION: The introduction of first-trimester combined screen caused a significant increase in CVS testing, whereas introduction of noninvasive prenatal testing caused a significant decrease in CVS testing.