Alpha-fetoprotein (AFP) is reduced at 36 weeks' gestation in pregnancies destined to deliver small for gestational age infants.

Alpha-fetoprotein (AFP) is a protein commonly used to screen for aneuploidy in pregnancy. This study measured circulating AFP in maternal plasma at 36 weeks' gestation preceding diagnosis of term preeclampsia or delivery of a small for gestational age infant (SGA; <10 % birthweight centile) in a case-cohort design (122 SGA; 23 preeclampsia; 182 controls). AFP was significantly reduced in SGA < 5th birthweight centile (n = 51; P = 0.002) but not changed preceding preeclampsia diagnosis. This suggests that AFP is reduced near term preceding SGA diagnosis and may have potential as a biomarker if combined with other candidate molecules.