Managing fetal growth restriction: surveillance tests and their interpretation

Predicting and preventing stillbirth at term

Stillbirth at term affects ∼1 per 1000 pregnancies at term in high income countries. A range of maternal characteristics are associated with stillbirth risk. However, given the low a priori risk of stillbirth, the vast majority of women with clinical risk factors would not experience a stillbirth in the absence of intervention. Stillbirth is the end point of multiple pathways, including both fetal growth restriction and fetal overgrowth. In most term stillbirths there is no mechanistic understanding of the cause of death and a sizeable proportion are completely unexplained. Term stillbirth is potentially preventable by early delivery, providing a rationale for screening. "Omic" analyses of blood taken prior to the onset of some of the conditions associated with stillbirth may help identify women at high risk and allow the potentially harmful intervention of early term medically indicated delivery to be targeted to the pregnancies most likely to benefit.

Trouble With the Curve: Pearls and Pitfalls in the Evaluation of Fetal Growth

OBJECTIVES

Poor fetal growth is one of the most important findings on an obstetric ultrasound (US) examination. First-trimester US is the most accurate means for dating pregnancies; however, dating based on last menstrual period remains the standard for determining gestational age. Discrepancies between menstrual and US dating can lead to the overdiagnosis of in utero growth restriction (IUGR). This article will demonstrate that as long as the fetal growth falls along a curve that parallels normal growth curves, appropriate growth has occurred regardless of the gestational age and weight percentile that has been assigned to the fetus.

METHODS

Following Institutional Review Board approval (HSD-00002969), 860 third-trimester fetal US examinations were retrospectively evaluated from January 1 through July 1, 2017, to determine whether they had normal growth curves. Outcome data on all cases were obtained from review of the medical records.

RESULTS

Of 216 fetuses (25%) suspected of IUGR based on a weight below the 10th percentile, 6 developed true IUGR: 5 that led to emergent delivery of fetuses weighing less than a 1000 g and 1 in utero fetal demise. The remaining 210 fetuses all had normal outcomes.

CONCLUSIONS

As long as the fetal growth falls along a curve that parallels normal growth curves, appropriate growth has occurred regardless of the gestational age and weight percentile that has been assigned to the fetus.