Oral or Poster Presentation
Concurrent Session 2C - DOHaD
Introduction: A poor in utero environment can adversely affect long-term health outcomes. Female rats prenatally exposed to maternal hypoxia during pregnancy may have accelerated reproductive aging within their ovaries and oviducts. However, pregnancy outcomes and vascular adaptations to pregnancy have not been characterized. We hypothesized that female offspring of dams that were exposed to hypoxia during late pregnancy would have compromised pregnancies and altered uterine artery function.
Methods: We used 4 month old non-pregnant and pregnant female rats that were born from dams exposed to hypoxia (11% oxygen) or normoxia (21% oxygen) during pregnancy (gestational days 15-21). In pregnant offspring, pregnancy outcomes were assessed at GD20 (term=GD22, n=5-7). Using an ex vivo pressure myograph system, endothelial-dependent relaxation (methylcholine) was assessed in uterine arteries of rats from all four groups (n=2-4). Data were analyzed by 2-way ANOVA.
Results: Twenty days after positive smear testing, only n=3 of 5 mated offspring from hypoxic pregnancies were carrying pregnancies. Our preliminary data showed that litter size was higher in pregnant control offspring (median 16, range 15-17) than pregnant offspring prenatally exposed to maternal hypoxia (median 13, range 5-16). Fetal crown-rump lengths from hypoxic pregnancy offspring (mean 3.8 ± 0.2 cm) tended to be smaller than those of control offspring (4.0 ± 0.2 cm; p=0.07). Endothelial-dependent relaxation was greater in uterine arteries from pregnant compared to non-pregnant dams (p<0.05), regardless of prenatal hypoxia. However, there was a main effect of prenatal hypoxia, which tended to impair endothelial-dependent vasodilation in both non-pregnant and pregnant offspring (p=0.06).
Conclusion: Our preliminary results suggest that female offspring exposed to hypoxia in utero have poor reproductive outcomes, which may be due to impaired uterine vascular function prior to pregnancy, as hypothesized. Identifying the underlying mechanisms may assist with improving reproductive outcomes in women born from complicated pregnancies.