350: Development of a customized fetal growth standard for a Mid-Western American population


      To derive coefficients for developing a customized growth chart for a Mid-Western American population.

      Study Design

      Retrospective cohort study of an ultrasound database with 72, 422 births between 1990-2008. After exclusion of preterm births, congenital anomalies, multifetal pregnancies, stillbirths and records with incomplete data, we defined a database of 50, 527 pregnancies. Coefficients for significant physiological and pathological variables affecting fetal growth were derived using backward stepwise multiple regression. Results were expressed for a standard mother (first pregnancy, height 163 cm, weight 64kg, European ethnic origin).


      The growth potential expressed as weight at 40 weeks in this population was 3521g (standard error: 402g). Significant physiological variables influencing fetal growth included maternal height (per cm: 7.3 + 0.0682 – 0.0043); weight (per kg: 8.15-0.1192+0.0013); parity (1: +109.4g; 2: +134.4g; 3: 151.6g; 4:152.6g); male/female gender (+/- 68.9g); ethnicity (African-American: -219.6g; Indian: -156.3; Middle East -112.5; Jewish-European: -86.1). Significant pathological factors affecting fetal growth were smoking (-213.9g), gestational diabetes (+93.6g), abruption (-105.1g) and hypertensive disorders (-52.3g). In addition, low as well as high maternal body mass index (BMI) were significantly associated with reduced birthweight at term (BMI <20: -21.2g; >30: -29.4g).


      Our findings validate previous studies implicating physiological and pathological factors in fetal growth. The derived coefficients allow the determination of customized growth potential individually adjusted, excluding known pathological factors.