Effects of race/ethnicity and BMI on the association between height and risk for spontaneous preterm birth.

OBJECTIVE: Short height and obesity have each been associated with increased risk for preterm birth (PTB). However, the effect of short height on PTB risk, across different race/ethnicities and body mass index (BMI) categories, has not been studied. Our objective was to determine the influence of maternal height on the risk for PTB within race/ethnic groups, BMI groups, or adjusted for weight. STUDY DESIGN: All California singleton live births from 2007 through 2010 were included from birth certificate data (vital statistics) linked to hospital discharge data. Prepregnancy BMI (kg/m(2)) was categorized as underweight (<18.5), normal (18.5-24.9), overweight (25.0-29.9), or obese (≥30.0). Maternal race/ethnicity was categorized as: non-Hispanic white, non-Hispanic black, Hispanic, and Asian. Maternal height was classified into 5 categories (shortest, short, middle, tall, tallest) based on racial/ethnic-specific height distributions, with the middle category serving as reference. Poisson regression models were used to estimate relative risks for the association between maternal height and risk of spontaneous PTB (<37 weeks and <32 weeks). Models were stratified on race/ethnicity and BMI. Generalized additive regression models were used to detect nonlinearity of the association. Covariates considered were: maternal age, weight, parity, prenatal care, education, medical payment, previous PTB, gestational and pregestational diabetes, pregestational hypertension, preeclampsia/eclampsia, and smoking. RESULTS: Among 1,655,385 California singleton live births, 5.2% were spontaneous PTB <37 weeks. Short stature (first height category) was associated with increased risk for PTB for non-Hispanic whites and Hispanics across all BMI categories. Among obese women, tall stature (fifth category) was associated with reduced risk for spontaneous PTB for non-Hispanic whites, Asians, and Hispanics. The same pattern of association was seen for height and risk for spontaneous PTB <32 weeks. In the generalized additive regression model plots, short stature was associated with increased risk for spontaneous PTB of <32 and <37 weeks of gestation among whites and Asians. However, this association was not observed for blacks and Hispanics. CONCLUSION: Maternal shorter height is associated with a modest increased risk for spontaneous PTB regardless of BMI. Our results suggest that PTB risk assessment should consider race/ethnicity-specific height with respect to the norm in addition to BMI assessment.

Therapeutic hypothermia during neonatal transport: current practices in California.

Therapeutic hypothermia initiated at <6 hours of age reduces death and disability in newborns ≥ 36 weeks' gestation with moderate to severe hypoxic ischemic encephalopathy. Given the limited therapeutic window, cooling during transport becomes a necessity. Our goal was to describe the current practice of therapeutic hypothermia during transport used in the state of California. All level III neonatal intensive care units (NICUs) were contacted to identify those units providing therapeutic hypothermia. An electronic questionnaire was sent to obtain basic information. Responses were received from 28 (100%) NICUs performing therapeutic hypothermia; 26 NICUs were cooling newborns and two were in the process of program development. Eighteen (64%) centers had cooled a patient in transport, six had not yet cooled in transport, and two do not plan to cool in transport. All 18 centers use passive cooling, except for two that perform both passive and active cooling, and 17 of 18 centers recommend initiation of cooling at the referral hospital. Reported difficulties include overcooling, undercooling, and bradycardia. Cooling on transport is being performed by majority of NICUs providing therapeutic hypothermia. Clinical protocols and devices for cooling in transport are essential to ensure safety and efficacy.