  To ensure optimal survival of the neonate, the biological timing of
parturition must be tightly controlled. Medical studies show that a variety of
endocrine systems play the role of a control system, establishing a dynamic
balance between the forces that cause uterine quiescence during pregnancy and
the forces that produce coordinated uterine contractility at parturition. These
control mechanism, and the factors that affect their performance, are still
poorly understood. To help fill this gap, we propose a model of the pregnant
uterus as a network of FitzHugh-Nagumo oscillators, with each cell symbolizing
the electrical activity of a myocyte. The model is augmented with sparse
adaptive control mechanisms representing the regulating endocrine functions.
The control system is characterized by the fraction of controlled sites, and
strength of control. We quantitatively find the conditions for which the
control system exhibit a balance between robustness (resilience against
perturbations) and flexibility (ability to switch function with minimal cost)
crucial for optimal neonatal survival. Specifically, we show that Braxton-Hicks
and Alvarez contractions, which are observed sporadic contractions of the
uterine muscle, serve as a safety valve against over-controlling, strategically
suppressed yet retained to optimize the control system's efficiency. Preterm
birth is suggested to be understood as a mis-identification of the control
boundaries. These insights contribute to advancing our understanding of
maternal-fetal health.
