AHA stage 1 hypertension and risk of small for gestational infants in nulliparous women

Abstract

Non-Obstetric guidelines by the American Heart Association (AHA) have redefined hypertension (HTN) into stages with a systolic blood pressure (BP) of 130-139 mmHg and/or diastolic BP of 80-89 mmHg defined as stage 1. It is well known that stage 1 HTN confers a significantly elevated risk of hypertensive disorders of pregnancy, but less is known regarding effects on placental function and subsequent birth weight. This study aims to assess risk of small for gestational age (SGA) birth weight in women stratified by non-Obstetric HTN cut points. This was a secondary analysis of a large prospective observational study investigating birth outcomes in nulliparous women (nuMoM2b). Subjects were excluded from the current analysis for incomplete outcome data, lack of first trimester blood pressure, structural fetal anomaly, and pregestational diabetes. Women were stratified based on documented first trimester blood pressure defined as normotensive (< 120/< 80), elevated (120-129/< 80), stage 1 HTN (130-139/80-89), or stage 2 HTN (either by medical history or BP ≥140/≥90). Logistic regression was used to generate adjusted odds ratio (aOR) and 95% confidence intervals (CI) for SGA birth weight (< 10%) and pregnancy induced HTN ([PIH], gestational HTN or preeclampsia). 7,951 pregnancies were included in the analysis with 601 (7.6%) meeting criteria for stage 1 hypertension based on AHA guidelines and 754 (9.5%) delivered SGA neonates. There were no significant differences in rates of SGA among groups < 10% (p=0.184) or < 3% (p=.920), Figure 1. There were also no differences in SGA after regression analysis (Table 1). Women with stage 1 HTN had the highest risk of PIH (aOR 2.1, CI 1.7-2.6) while stage 2 HTN was not significant after adjustment (aOR 1.3, CI 0.92-1.8). Nulliparous women with stage 1 hypertension by non-obstetric guidelines do not have an elevated risk of SGA despite and increased risk of hypertensive disorders of pregnancy.View Large Image Figure ViewerDownload Hi-res image Download (PPT)