AGA-primed uteri compared with SGA-primed uteri and the success of subsequent in utero fetal programming.

Objective: To assess whether risk for early mortality is increased with recurrent small for gestational age (SGA) compared with nonrecurrent SGA.

Methods: 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.

Results: 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.

Conclusions: Fetal programming switch in subsequent gestation adversely affects early survival of affected infants compared with those with no change in fetal growth pattern.