2ND-TRIMESTER PLACENTAL VOLUMES PREDICT BIRTH-WEIGHT AT TERM

OBJECTIVE: To test the hypothesis that second-trimester placental grow th is a major determinant of size at birth in healthy, active women. M ETHODS: Three serial measurements of fetal morphometry and placental v olume were obtained between the 14th and 26th weeks of an accurately d ated singleton pregnancy in 40 subjects. RESULTS: Second-trimester pla cental volumes were variable, increasing from (mean +/- standard devia tion) 130 +/- 35 to 248 +/- 67 and to 375 +/- 92 cm(3) at 16, 20, and 24 weeks, with an average growth rate of 31 +/- 8 cm(3)/weeks. At deli very, fresh placental volumes and birth weights were also variable, ra nging between 304-823 cm(3) and 2.6-4.4 kg, respectively. Significant correlations (r > 0.79) were present between second-trimester placenta l volume or growth rate and placental volume at delivery and birth wei ght, corrected for gestational age and infant sex. However, correlatio ns between second-trimester fetal biometry and both corrected birth we ight and birth weight percentile were poor (r < 0.45). CONCLUSION: Sec ond-trimester placental volumes and growth rates ave good predictors o f size at birth in healthy, active women. We speculate that this techn ique may have real value as an early screening tool to identify cases at risk of anomalous third-trimester growth.