AGA-Primed Uteri Compared With SGA-Primed Uteri and the Success of Subsequent In Utero Fetal Programming

Abstract

To assess whether risk for early mortality is increased with recurrent small for gestational age (SGA) compared with nonrecurrent SGA. We used the Missouri maternally linked cohort data containing births from 1978-1997. We identified mothers according to four categories: 1) appropriate for gestational age (AGA)-AGA: both first and second pregnancies were AGA; 2) AGA-SGA: first pregnancy was AGA, second pregnancy outcome changed to SGA (a switch); 3) SGA-AGA: first pregnancy was SGA, second pregnancy outcome AGA (a switch); 4) SGA-SGA: both first and second pregnancies were SGA. We then compared the success of fetal programming in the second pregnancy with a switch compared with a pregnancy without a switch (AGA-SGA compared with SGA-SGA; and SGA-AGA compared with AGA-AGA). We used neonatal mortality as primary outcome with infant and postneonatal mortality as secondary outcomes. Appropriate for gestational age infants from a SGA-primed uterus (SGA-AGA switch) had a 19% (odds ratio 1.19; 95% confidence interval 1.11-1.28) and 29% (odds ratio 1.29; 95% confidence interval 1.17-1.42) greater likelihood of infant and neonatal mortality, respectively, when compared with AGA infants from AGA-primed uterus (AGA-AGA; nonswitch). Approximately the same magnitude of risk elevation for neonatal and infant mortality was noted among SGA infants resulting from AGA-primed uterus (a switch) as among SGA infants from SGA-primed uterus (a nonswitch). Overall, the greatest risk of neonatal, infant, and postneonatal mortality was associated with an AGA-SGA switch. Fetal programming switch in subsequent gestation adversely affects early survival of affected infants compared with those with no change in fetal growth pattern.