Stephen A. Myers

Placental Growth Response to Maternal Insulin in Early Pregnancy

CONTEXT The sensitivity of the placenta to maternal insulin remains controversial. Early pregnancy may be a time of increased placental sensitivity to maternal insulin because insulin receptors are abundant on the syncytiotrophoblast in the first trimester but are far fewer at term. HYPOTHESIS Maternal insulin secretory response in early, but not late, pregnancy is positively associated with placental growth. DESIGN This is a secondary analysis of a cohort of women (n = 40) recruited before pregnancy. OUTCOME MEASURES An iv glucose tolerance test was administered before pregnancy and in early (12-14 weeks) and late (34-36 weeks) pregnancy. Placental volume throughout gestation (in a subset of women via 3-dimensional ultrasound) and weight at birth were recorded. RESULTS Total insulin secretory response in early pregnancy was positively associated with placental volume in early pregnancy (R = 0.79, P = 0.04) and placental weight at term (R = 0.42, P = 0.007). Insulin secretory response before and in late pregnancy was not significantly associated with placental growth. Although neonatal fat mass was strongly correlated with placental weight at term (R = 0.449, P = 0.0003), maternal insulin secretory response was related to neonatal fat mass only at birth in male offspring (R = 0.59, P = 0.008). CONCLUSIONS Maternal insulin secretory response in early pregnancy was strongly related to placental weight at birth. Thus, in early pregnancy, increased maternal insulin response as seen in obesity and gestational diabetes mellitus may be a key influence on placental growth, possibly due to the enhanced presence of placental insulin receptors on the maternal villous membrane early in gestation.

Comparison of 2- and 3-Dimensional Sonography for Estimation of Birth Weight and Neonatal Adiposity in the Setting of Suspected Fetal Macrosomia

To compare the accuracy of 2‐dimensional (2D) and 3‐dimensional (3D) fetal measurements for prediction of birth weight Z score and neonatal adiposity (percent body fat) in the setting of suspected fetal macrosomia.

The systematic error in the estimation of fetal weight and the underestimation of fetal growth restriction

&NA; Fetal growth restriction (FGR) is associated with an increased risk of perinatal morbidity and mortality and has lifetime implications for the risk of chronic medical conditions. Antenatal diagnosis of FGR remains poor, with the majority of cases remaining undiagnosed. Although several factors contribute to the underdiagnosis of FGR, the error in ultrasound estimation of fetal weight (EFW) generally is not considered in clinical practice. In this commentary, we suggest that the intrinsic, or systematic, error in ultrasound EFW is a significant factor contributing to the underestimation of fetuses predicted to have FGR and should be incorporated into screening and surveillance recommendations. To illustrate this point, we present an analytic model of published data from the Eunice Kennedy Shriver National Institute of Child Health and Human Development Fetal Growth Studies characterizing and quantifying the impact of the systematic error in ultrasound EFW on the underdiagnosis of FGR. Independent of the centile at which the risk of adverse outcome related to FGR begins, whether the 10th, 5th or 3rd percentile, our analysis suggests the need to modify to the current paradigm for identifying and responding to fetuses estimated to be at risk.