Table 1.
Comparison of animal models focusing on characteristics of gestation, parturition, and relative advantages and disadvantages of each model.
| Characteristic | Human | Monkey | Sheep | Guinea Pig | Mouse |
|---|---|---|---|---|---|
| Gestational length in days (mean ± SD | 280 ± 14 | 167 ± 7 (M. mulatta) 172 ± 7 (M. nemestrina) |
144-151 | 60-70 | 19-21 |
| Litter size (mean or range) | 1 | 1 | 1-3 | 2-4 | 10-12 (strain specific) |
| Placenta | Hemomonochorial, villous, discoid | Hemomonochorial, villous, bi-discoid | Epithelial-chorial, cotyledonary | Hemomonochorial, labyrinthine, discoid | Hemotrichorial, labyrinthine |
| Uterus | Unicornuate | Unicornuate | Bicornuate | Duplex uterus (2 uterine horns, 2 cervices) | |
| Induction of preterm birth | Prostaglandin, anti-progestin, oxytocin | Inoculation of bacteria, LPS, or cytokines (IL-1β) | Fetal ACTH, glucocorticoid, anti-progestin | Prostaglandin, anti-progestin, oxytocin | Anti-progestin, ovariectomy |
| Advantages/Disadvantages | Directly translational, but limited to cross-sectional analysis | Directly translational, but expensive and limited in availability | Chronically catheterized model possible | Similar placenta to humans, but spontaneous preterm birth can occur | Low cost, small size |
Abbreviations:
ACTH: adrenocorticotropin releasing hormone
SD: standard deviation